WO2018095053A1 - Lithium cobalt oxide positive electrode material and preparation method therefor and lithium ion secondary battery - Google Patents

Abstract

Provided is a doped-type lithium cobalt oxide positive electrode material. The general formula of the doped-type lithium cobalt oxide is Li_1+zCo_1-x-yMa_xMb_yO₂, wherein 0 ≤ x ≤ 0.01, 0 ≤ y ≤ 0.01, and -0.05 ≤ z ≤ 0.08; the Ma is a doped element with an unchangeable valence and is at least one of Al, Ga, Hf, Mg, Sn, Zn and Zr; and the Mb is a doped element with a variable valence and is at least one of Ni, Mn, V, Mo, Nb, Cu, Fe, In, W and Cr. The doping of the element with an unchangeable valence is done by substituting, such that the distortion of a laminate structure caused by delithiation is minimized to the largest extent; and the doping of the element with a variable valence is done through the gap, and same element reconciles and delays the oxidation of Co³⁺ during charging.

Description

Lithium cobaltate cathode material, preparation method thereof and lithium ion secondary battery Technical field

The present invention relates to the field of materials, and in particular to a lithium cobaltate cathode material, a method for preparing the lithium cobaltate cathode material, and a lithium ion secondary battery.

Background technique

At present, lithium-ion batteries have been widely used in various electronic devices (such as mobile phones and tablet computers). As people's performance requirements for electronic devices continue to increase, higher demands are placed on the volumetric energy density of lithium-ion batteries. It should be noted that the volumetric energy density of the battery = discharge capacity × discharge platform voltage × compaction density. Increasing the charge cut-off voltage of the positive electrode material can increase the discharge capacity and the discharge platform voltage, thereby increasing the volumetric energy density thereof. However, when the lithium ion battery is charged to 4.2V, lithium ions in LiCoO ₂ are decomposed to form Li _1-x CoO ₂ ( _{0 ≤ x ≤} 0.5), and when the charging voltage is increased to 4.4 V or more, LiCoO ₂ is present. More lithium ion liberation leads to the conversion of LiCoO ₂ from hexagonal to monoclinic and no longer has the function of reversible intercalation and deintercalation of lithium ions; at the same time, the process is accompanied by the dissolution of cobalt ions in the electrolyte, so The actual capacity of lithium cobalt battery cathode material lithium cobaltate (150 mAh·g ^-1 ) is much lower than its theoretical capacity (274 mAh·g ^-1 ).

Therefore, there is an urgent need to develop a lithium ion battery positive electrode material which has good cycle performance at high voltage, high capacitance, and can buffer or release stress caused by changes in lattice constant during charge and discharge.

Summary of the invention

In view of this, the first aspect of the embodiments of the present invention provides a lithium ion battery positive electrode material having good cycle performance, high capacitance, and capable of buffering or releasing stress caused by changes in lattice constant during charge and discharge.

In a first aspect, the present invention discloses a lithium cobaltate cathode material, the lithium cobaltate cathode material comprising doped lithium cobaltate;

Wherein, the substance constituting the doped lithium cobaltate has a general formula of Li _1+z Co _1-xy Ma _x Mb _y O ₂ ; wherein 0≤x≤0.01, 0≤y≤0.01, -0.05≤z ≤ 0.08; wherein the Ma is a doped constant valence element; the Ma is at least one of Al, Ga, Hf, Mg, Sn, Zn, Zr; wherein the Mb is a doped variable element The Mb is at least one of Ni, Mn, V, Mo, Nb, Cu, Fe, In, W, Cr, and the lattice of the doped lithium cobalt oxide comprises a cobalt ion layer and an oxygen ion layer a main body layer formed and a lithium ion layer distributed on both sides of the main body layer, the main body layer further comprising the doped constant valence element Ma and the variable element Mb, the constant valence element Ma Substituting a cobalt ion in the bulk layer.

In combination with the first aspect, it is to be noted that the surface coating layer is further included; wherein the surface coating layer covers the surface of the doped lithium cobaltate, and the material constituting the surface coating layer passes through The formula is Li _γ1 Mc _γ2 O _γ3 ; wherein, Mc is Cr, Co, Ni, Cu, Mn, Ti, Zr, Hf, La, Nb, In, W, Ta, Ba, Te, Y, Sb, P At least one, wherein the γ1, γ2, and γ3 may be any positive number but need to satisfy the following formula, γ1+A*γ2=2*γ3, and the A is a valence of Mc. The material of the surface coating layer includes an inorganic solid electrolyte material and a high voltage active material.

In combination with the lithium cobaltate cathode material disclosed above, it is further noted that the constant valence element Ma is ionically bonded to the bulk plate layer, and the body plate layer includes an oxygen ion layer and a cobalt ion layer which are sequentially arranged. And an oxygen ion layer, the cobalt ion layer being located between the two oxygen ion layers

In combination with the lithium cobaltate cathode material disclosed above, it is further noted that the lattice c-axis size of the lithium cobaltate cathode material varies within a range of

In combination with the lithium cobaltate cathode material disclosed above, it is further noted that 0.0005 ≤ x ≤ 0.005. For example x can Is 0.004 or 0.003.

In combination with the lithium cobaltate cathode material disclosed above, it is further noted that 0.0005 ≤ y ≤ 0.005. For example, y can be 0.005 or 0.0008.

In combination with the lithium cobaltate cathode material disclosed above, it is further noted that -0.01 ≤ z ≤ 0.03. z can be 0.01 or 0.02;

In combination with the lithium cobaltate cathode material disclosed above, it should be noted that the lattice of the doped lithium cobalt oxide includes a main body layer mainly composed of a cobalt ion layer and an oxygen ion layer, and is distributed on the main body layer a lithium ion layer on both sides, the body plate layer further comprising the doped constant valence element Ma and the variable valence element Mb, wherein the constant valence element Ma is used to replace the main layer layer before doping a cobalt ion; the variable element Mb is filled between the cobalt ion layer and the oxygen ion layer of the bulk layer, specifically, the three oxygen ions of the variable element ions are filled on a cobalt ion and an oxygen ion layer In a tetrahedral space composed of vertices, or three cobalt ions filled on a layer of oxygen ions and a cobalt ion, a tetrahedral space composed of vertices.

A second aspect of the invention discloses a method for preparing a lithium cobaltate cathode material, the method comprising:

The cobalt source and the compound containing the constant valence element Ma are disposed as an aqueous solution, and the aqueous solution is mixed with the complex solution and the precipitant solution to cause the aqueous solution to react with the complex solution and the precipitant solution to obtain a solution. a potassium or hydroxide of a cobalt-doped cobalt; wherein the Ma is at least one of Al, Ga, Hf, Mg, Sn, Zn, Zr;

Mixing the obtained cobalt or hydroxide of the doped cobalt with the compound containing the valence element Mb, and sintering the mixed compound at a temperature of 800 to 1000 ° C for 4-10 hours to obtain the An oxide precursor of Co co-doped with Ma; wherein the Mb is at least one of Ni, Mn, V, Mo, Nb, Cu, Fe, In, W, Cr;

The obtained oxide precursor of Co co-doped with Ma and Mb is mixed with a lithium source, and the mixture of the oxide precursor and the lithium source is sintered at a temperature of 950 to 1100 ° C for 8 to 16 hours. Obtaining a doped lithium cobalt oxide co-doped with the Ma and Mb;

The lithium source, the compound containing the element Mc, and the obtained doped lithium cobalt oxide doped with the Ma and Mb are mixed and sintered at a temperature of 850 to 1050 ° C for 8 to 16 hours to obtain the lithium cobaltate positive electrode. a material, wherein the Mc is at least one of Cr, Co, Ni, Cu, Mn, Ti, Zr, Hf, La, Nb, In, W, Ta, Ba, Te, Y, Sb, P.

Among them, it should be pointed out that the last step of the second aspect is to be treated by solid phase coating.

It should be noted that the last step of the second aspect can be replaced by: a liquid source coating method, a lithium source and a compound containing the element Mc and the obtained doped lithium cobalt oxide co-doped with Ma and Mb. After mixing and drying in the liquid phase, the mixture is sintered at a temperature of 850 to 1050 ° C for 8 to 16 hours to obtain a lithium cobaltate cathode material doped and surface-coated and co-modified.

In combination with the second aspect, in a first possible implementation of the second aspect, the aqueous solution is mixed with a complex solution and a precipitant solution, such that the aqueous solution and the complex solution and the precipitant solution Reaction crystallization, obtaining the carbonate or hydroxide of the cobalt-doped cobalt comprises: mixing the aqueous solution containing the Co ion and the constant-valent element Ma ion with the precipitant solution by using a parallel flow control flow; wherein, the cocurrent flow The flow rate of the control flow does not exceed 200 L/h, the stirring speed does not exceed 200 rpm, and the crystallization temperature does not exceed 100 °C.

In combination with the second aspect or the first possible implementation of the second aspect, it should be noted that

The cobalt source is at least one of cobalt acetate, cobalt oxalate, cobalt nitrate, cobalt sulfate, and cobalt chloride; the compound containing a constant valence element Ma is a nitrate, oxalate, acetate containing Ma. At least one of fluoride, chloride, and sulfate; the concentration of Co ion in the aqueous solution containing Co ion and the constant-valent element Ma ion is 0.5-2.0 mol/L; the precipitant solution is a strong alkali solution, carbonate a solution, an oxalic acid or an oxalate solution; the complexing agent solution is an ammonia water or an aminohydroxy acid salt solution; the compound containing the variable element Mb is selected from the group consisting of oxides, hydroxides, carbonates, nitric acids containing Mb At least one of a salt, an oxalate, and an acetate; the lithium source is at least one of lithium hydroxide, lithium nitrate, lithium carbonate, lithium oxalate, lithium acetate, lithium oxide, and lithium citrate; or The compound containing the element Mc is at least one of an oxide, a hydroxide, a carbonate, a nitrate, an oxalate, and an acetate containing Mc.

A third aspect of the invention discloses a method for preparing another lithium cobaltate cathode material, the method comprising:

The cobalt source and the compound containing the constant valence element Ma are disposed as an aqueous solution, and the aqueous solution is mixed with the complex solution and the precipitant solution to cause the aqueous solution to react with the complex solution and the precipitant solution to obtain a solution. a potassium or hydroxide of a cobalt-doped cobalt; wherein the Ma is at least one of Al, Ga, Hf, Mg, Sn, Zn, Zr;

The obtained cobalt-doped cobalt carbonate or hydroxide is sintered at a temperature of 900 to 1000 ° C to obtain a Ma-doped precursor Co ₃ O ₄ , wherein the sintering time is 4 to 10 h. ;

The lithium source, the Mb-containing compound and the Ma-doped precursor Co ₃ O ₄ are sintered at a temperature of 950 to 1100 ° C for 8 to 16 hours to obtain a doped lithium cobalt oxide co-doped with Ma and Mb. ;

The lithium source, the compound containing the element Mc, and the obtained doped lithium cobalt oxide doped with the Ma and Mb are mixed and sintered at a temperature of 850 to 1050 ° C for 8 to 16 hours to obtain the lithium cobaltate positive electrode. a material, wherein the Mc is at least one of Cr, Co, Ni, Cu, Mn, Ti, Zr, Hf, La, Nb, In, W, Ta, Ba, Te, Y, Sb, P.

It should be noted that the last step of the third aspect can be replaced by: a liquid source coating method, a lithium source and a compound containing the element Mc and the obtained doped lithium cobalt oxide co-doped with Ma and Mb. After mixing and drying in the liquid phase, the mixture is sintered at a temperature of 850 to 1050 ° C for 8 to 16 hours to obtain a lithium cobaltate cathode material doped and surface-coated and co-modified.

In combination with the third aspect, in a first possible implementation manner of the third aspect, the aqueous solution is mixed with the complex solution and the precipitant solution, so that the aqueous solution and the complex solution and the precipitant solution are Reaction crystallization to obtain the carbonate or hydroxide of the Ma-doped cobalt includes:

The aqueous solution containing Co ions and the constant-valent element Ma ions is mixed with the precipitating agent solution by means of cocurrent flow control; wherein the flow rate of the parallel flow control does not exceed 200 L/h, the stirring speed does not exceed 200 rpm, and the crystallization temperature does not exceed 100. °C.

In combination with the third aspect or the first possible implementation of the third aspect, the cobalt source is at least one of cobalt acetate, cobalt oxalate, cobalt nitrate, cobalt sulfate, and cobalt chloride; The compound is at least one of nitrate, oxalate, acetate, fluoride, chloride, and sulfate containing Ma; the concentration of Co ion in the aqueous solution containing Co ion and the constant-valent element Ma ion is 0.5 to 2.0. Mol/L; the precipitant solution is a strong alkali solution, a carbonate solution, an oxalic acid or an oxalate solution; the complexing agent solution is an ammonia water or an aminohydroxy acid salt solution; and the compound containing the variable element Mb is At least one selected from the group consisting of oxides, hydroxides, carbonates, nitrates, oxalates, and acetates containing Mb; the lithium source is lithium hydroxide, lithium nitrate, lithium carbonate, lithium oxalate, At least one of lithium acetate, lithium oxide, and lithium citrate; or the compound containing the element Mc is an oxide, hydroxide, carbonate, nitrate, oxalate, or acetate containing Mc At least one of them.

A fourth aspect of the invention discloses a lithium ion battery comprising a positive electrode sheet, a negative electrode sheet, an electrolyte solution and a separator disposed between the positive and negative electrode sheets, wherein the positive electrode sheet includes a positive electrode current collector and a distribution The positive electrode active material layer on the positive electrode current collector, wherein the positive electrode active material layer uses the lithium cobaltate positive electrode material according to any one of the first aspect or the first aspect of the first aspect as the positive electrode active material.

Further, it should be noted that the active capacity of the lithium cobaltate cathode material is greater than 190 mAh/g.

A fifth aspect of the invention discloses an electronic device comprising the lithium ion battery of the fourth aspect.

As can be seen from the above, an embodiment of the present invention discloses a lithium cobaltate cathode material, the lithium cobaltate cathode material comprising doped lithium cobaltate and a surface coating layer; wherein the doped lithium cobalt oxide is passed The formula is Li _1+z Co _1-xy Ma _x Mb _y O ₂ ; wherein 0≤x≤0.01, 0≤y≤0.01, -0.05≤z≤0.08; wherein the Ma is a doped constant valence element The Ma is at least one of Al, Ga, Hf, Mg, Sn, Zn, Zr; wherein the Mb is a doped variable element; the Mb is Ni, Mn, V, Mo, Nb, At least one of Cu, Fe, In, W, and Cr; according to the above description, the lithium cobaltate cathode material provided by the present invention is doped with a valence element and doped with a constant valence element. Among them, the constant valence element replaces the cobalt ion in the main layer of the lithium cobalt oxide lattice structure by the substitution doping method to ensure that the skeleton-cobalt position of the layered structure is not distorted by oxidation, and the high voltage can be stabilized. The stability of the layered structure of the lithium cobaltate cathode material in use; on the other hand, the variable element is doped through the gap, and is filled between the cobalt ion layer and the oxygen ion layer of the main layer of the lithium cobalt oxide lattice structure, specifically, The valence element ions are filled in a tetrahedral space composed of three oxygen ions on a cobalt ion and an oxygen ion layer, or three cobalt ions filled on one oxygen ion and one cobalt ion layer are vertices In the tetrahedral space formed, the stress generated by the skeleton change of the layered structure is alleviated or released, and the purpose of stabilizing the lithium cobaltate layer structure is achieved. The invention combines the principle and process of phase transformation of a lithium cobaltate layer structure in a high voltage scene, fully exerts the advantages of each doping element, and significantly improves the comprehensive performance of the cathode material.

The advantages of the embodiments of the present invention will be set forth in part in the description which follows.

DRAWINGS

1 is a schematic view showing a lattice structure of a layered lithium cobalt oxide provided by an embodiment of the present invention;

2 is a schematic diagram of a phase change process of lithium cobaltate in different states of charge;

3 is a schematic diagram of phase transition of lithium cobaltate during charging;

4 is a schematic view showing substitution doping and gap doping in a lithium cobaltate layered structure;

5 is an X-ray diffraction spectrum of a lithium cobaltate cathode material according to an embodiment of the present invention;

6(a) is a SEM (scanning electron microscope) diagram of a lithium cobaltate cathode material according to an embodiment of the present invention;

6(b) is a TEM (Transmission Electroscope) diagram of a lithium cobaltate cathode material according to an embodiment of the present invention;

7 is a particle size distribution of a lithium cobaltate cathode material according to an embodiment of the present invention;

8 is a first charge and discharge curve of a lithium cobaltate cathode material according to an embodiment of the present invention;

9 is a cycle curve of a lithium cobaltate cathode material according to an embodiment of the present invention;

FIG. 10 is a schematic diagram of a lithium ion battery including a lithium cobaltate cathode material according to an embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present invention will be described below in conjunction with the accompanying drawings in the embodiments of the present invention.

空间群。图1所示为所述钴酸锂晶格结构中层状结构的一个晶胞，沿z轴由上至下，分别为钴-氧-锂-氧-钴-氧-锂-氧-钴-氧-锂-氧-钴层，分别对应于数字1-13，其中氧离子形成一层密堆积层，钴层和锂层交替分布与氧层两侧；钴层与氧层构成CoO₂主体板层，如图1中的第4-6层以及8-10层为所述主体板层。所述CoO₂的板层结构为锂离子的迁移提供二维通道，如图1中第7层即为夹在CoO₂板层之间的锂离子迁移层。1 is a lattice structure of layered lithium cobaltate. As shown in FIG. 1, the lattice structure of the lithium cobaltate has a typical α-NaFeO ₂ structure and belongs to a hexagonal system.

Space group. Figure 1 shows a unit cell of a layered structure in the lithium cobaltate lattice structure, from top to bottom along the z-axis, respectively cobalt-oxygen-lithium-oxy-cobalt-oxygen-lithium-oxygen-cobalt- The oxy-lithium-oxygen-cobalt layers correspond to the numbers 1-13, respectively, wherein the oxygen ions form a close-packed layer, the cobalt layer and the lithium layer are alternately distributed on both sides of the oxygen layer; the cobalt layer and the oxygen layer constitute the CoO ₂ main plate The layers, such as layers 4-6 and 8-10 in Fig. 1, are the main body layers. The ply structure of the CoO ₂ provides a two-dimensional channel for the migration of lithium ions, and the seventh layer in FIG. 1 is a lithium ion transport layer sandwiched between the CoO ₂ plate layers.

Due to the pursuit of high energy density, the charging cut-off voltage of lithium cobaltate operation has been continuously improved, from 4.2V to 4.35V. To today's 4.4V. For every 0.1V increase in operating voltage, the lithium cobalt oxide discharge capacity can be increased by about 10%, and the discharge voltage platform is increased by about 0.02V. However, after the cut-off voltage is increased (especially above 4.3 V), microcrack generation and cobalt dissolution occur due to the instability of the layered lithium cobalt oxide structure and surface instability, causing collapse of the lattice structure and irreversible phase transition. Figure 2 depicts the specific phase change process during charging. The specific process is as follows:

For Li _x CoO ₂ , when x=1～0.9, lithium cobaltate maintains the initial layered structure and is hexagonal (Fig. 3(a)); when x=0.9~0.78, the initial hexagonal system changes to twice Hexagonal system, this region is a two-phase coexistence zone. The reason for this transformation is that as the lithium ions are removed, a Mott insulator is produced. The voltage platform corresponding to this phase change is 3.97V; when x<0.78 The initial hexagonal system disappears and becomes a single secondary hexagonal system; in this process, as the lithium ions continue to escape, the negatively charged oxygen-oxygen electrostatic repulsion between adjacent CoO ₂ layers increases, causing c Continue to increase, this process until x is close to 0.5; when x < 0.5, the secondary hexagonal system begins to transform into a monoclinic system; in the region of x = 0.5 ~ 0.46, lithium cobaltate is monoclinic; When x is close to 0.46, the monoclinic system is again transformed into a hexagonal system. This transformation is caused by the realignment of lithium ions in the lithium layer, which corresponds to the voltage platform of 4.08V and 4.15V. The original layered structure in 3(b) is twisted, causing the c-axis index to change; when x<0.46, the voltage exceeds 4.2V, The c-axis index of the hexagonal system begins to decrease sharply; when x=0.22, the hexagonal system begins to transform into a secondary monoclinic system; after that, when x=0.22~0.18, it is a hexagonal system and two. The two-phase coexistence region of the sub-monoclinic system, the corresponding voltage platform is 4.55V; the transition of these two phases reaches the pole at x=0.148, and as the lithium ions continue to move out, the hexagonal system continues to the second Monoclinic transformation; subsequently, LixCoO ₂ undergoes frequent phase transitions, a secondary monoclinic phase region appears, and transforms into a hexagonal system with a decrease in x until the lithium ions are completely detached, and the structure becomes a single layer. CoO ₂ , the CoO ₂ structure produced by the phase change can be seen in Figure 3(c). After multiple charge and discharge, the LixCoO ₂ layer begins to crack (Fig. 3(d)), and many broken crystal particles appear on the side close to the electrolyte (Fig. 3(e)), which is due to the cobalt layer in contact with the electrolyte. Decomposition, caused by the collapse of the crystal lattice.

The key to the development of lithium cobalt oxide cathode material is to solve the frequent phase transition process of the layered structure of lithium cobalt oxide and the damage of the stress generated during the phase transition process in the high voltage and deep delithiation state; In the deep delithiation state, the strong oxidizing property of the tetravalent cobalt ion converted from trivalent cobalt in the lithium cobaltate to the carbonate solvent and the dissolution of the cobalt ion in the electrolytic solution are solved. Therefore, the development of lithium cobalt oxide cathode material under high voltage use scenarios has become one of the development trends of current batteries.

In view of the above problems, the present invention proposes an element doping in which two forms coexist with lithium cobaltate: one doping is a method in which a constant valence element is doped by substitution, and one of the main layer of the lithium cobalt oxide lattice structure is replaced. Cobalt ion. During the charging of lithium cobaltate, Co ³⁺ will oxidize to Co ⁴⁺ , and the ionic radius will change, resulting in instability of the bulk layer structure. On the other hand, in the strong oxidizing atmosphere in contact with the electrolyte, cobalt ions Dissolution will occur, further damaging the structure of the bulk layer. By replacing the doping element with a doping method, it replaces a cobalt ion in the bulk layer of the lithium cobalt oxide lattice structure. On the one hand, it can ensure that the skeleton and cobalt sites of the layered structure are not distorted by oxidation, and the lithium ion is maintained. The stability of the transmission channel, on the other hand, the valence state of these constant-valent element ions does not change at the position of cobalt, and the ionic radius does not change, thereby maintaining the stability of the lithium cobaltate layer structure; Figure 4 shows the constant-valent element In the substitution doping method of ions, it can be seen that the CoO2 main plate layer composed of cobalt and oxygen is sequentially arranged according to the oxygen layer, the cobalt layer and the oxygen layer (such as 4-6 layers or 8-10 layers in FIG. 4), and the price is constant. The elemental ions enter the cobalt layer and replace one of the cobalt ions to form a substitution doping; the constant valence element ions change the layer spacing of the lithium cobaltate layer structure because the ionic radius is different from the original cobalt ion radius. When selecting the constant valence element, the factor of the ionic radius should be fully considered. The closer the doping ion is to the substituted ion, the smaller the lattice distortion caused by the substitution.

In the lithium cobaltate system, the ionic radius of Co ³⁺ is 0.0685 nm, the ionic radius of Li ⁺ is 0.090 nm, and the ionic radius of O ²⁻ is 0.126 nm. Considering the above information, in the present invention, in order to stabilize the bulk structure, the doped valence element Ma has an ionic radius ranging from 0.055 nm to 0.087 nm, which can be selected from the following elements: Al (Al ³⁺ , Ion radius is 0.0675 nm), Ga (Ga ³⁺ , ionic radius 0.076 nm), Hf (Hf ⁴⁺ , ionic radius 0.085 nm), Mg (Mg ²⁺ , ionic radius 0.086 nm), Sn (Sn ^{4 +} , ionic radius: 0.083 nm), Zn (Zn ²⁺ , ionic radius: 0.088 nm), Zr (Zr ⁴⁺ , ionic radius: 0.086 nm), and the like. The doping element has an ionic radius and a valence state close to that of Co ³⁺ , and can replace a cobalt ion in the main layer of the lithium cobalt oxide lattice structure, thereby ensuring that the skeleton and the cobalt site of the layered structure are not distorted by oxidation. The lithium ion transport channel is maintained to improve the stability of the layered structure of the positive electrode material.

Another doping is to fill the cobalt ion layer and the oxygen ion layer of the main layer of the lithium cobalt oxide lattice structure by doping the variable element through the gap. FIG. 4 illustrates the gap doping of the variable element ions. In the mode, in FIG. 4, the valence element ions are filled between the cobalt ion layer and the oxygen ion layer of the main layer of the lithium cobalt oxide lattice structure, specifically, the valence element ions are filled on the cobalt ion and the oxygen ion layer. a tetrahedral space in which oxygen ions are apex, or a tetrahedral space in which three cobalt ions doped on an oxygen ion and a cobalt ion layer are vertices; these doped valence element ions The ionic bond is combined with the negatively charged CoO ₂ bulk layer. On the one hand, in the oxidizing atmosphere, the valence element ions oxidize preferentially over Co ³⁺ , thereby delaying the occurrence of Co ³⁺ oxidation. On the other hand, when the valence element occurs When oxidized, its ionic radius will change due to loss of electrons, thereby improving lattice adaptability, mitigating or releasing the stress caused by the skeleton change of the layered structure, ensuring the skeleton of the layered structure and maintaining lithium ions. Stable output channel.

For the selection of the valence element for gap doping, the ionic radius also needs to be close to the size of the cobalt ion, and the oxidizability is stronger than Co ³⁺ . The doped variable element Mb can be selected from the following elements: Ni (with Ni ^3+/4+ valence), Mn (with Mn ^3+/4+/5+/6+ valence), V (with V ^3+/4+/5+ valence), Mo (with Mo ^3+/4+/5+/6+ valence), Nb (with Nb ^3+/4+/5+ valence), Cu (with Cu ^2+/3+ valence), Fe (with Fe ^3+/4+/6+ valence), In (with In ^1+/3+ valence), W (with W ^{4+/5+/6) +} valence state), Cr (with Cr ^{2+/3+/4+/5+/6+} valence state), etc. These elements are filled in a gap doping manner between the cobalt ion layer and the oxygen ion layer of the main layer of the lithium cobaltate lattice structure, and are ionically bonded to the negatively charged CoO ₂ bulk layer, which is strong in the electrolyte. In an oxidizing atmosphere, oxidation occurs in preference to Co ³⁺ , resulting in valence changes and ionic radius changes, thereby releasing or mitigating stress caused by changes in lattice size.

By doping the above two types of elements, a doped lithium cobaltate is obtained: Li _1+z Co _1-xy Ma _x Mb _y O ₂ (generally, 0≤x≤0.01, 0≤y≤0.01, -0.05 ≤ z ≤ 0.08; preferably, 0.0005 ≤ x ≤ 0.005, 0.0005 ≤ y ≤ 0.005, -0.01 ≤ z ≤ 0.03), Ma is a doped constant valence element Al, Ga, Hf, Mg, Sn, Zn, Zr One or more of such doping is a substitution doping of the above element instead of a cobalt site; Mb is a doped variable element Ni, Mn, V, Mo, Nb, Cu, Fe, In, W, Cr One or more of such doping is doped with a gap into which the above element enters the lithium cobaltate lattice gap.

Several possibilities for the doped lithium cobaltate prepared above are listed below (but this patent is not limited to the possibilities shown below), wherein the doped lithium cobaltate may be, but not limited to, LiCo _0.996 Al _0.003 Ni _0.001 O ₂ , LiCo _0.996 Al _0.002 Ni _0.002 O ₂ , Li _1.02 Co _0.995 Al _0.004 Mn _0.001 O ₂ , Li _1.02 Co _0.994 Al _0.004 Mn _0.002 O ₂ , Li _1.03 Co _0.995 Al _0.004 Cr _0.001 O ₂ , Li _1.03 Co _0.994 Al _0.004 Cr _0.002 O ₂

(没有进行掺杂的钴酸锂c轴尺寸为

)或0.02％～0.3％。 The doped lithium cobalt oxide prepared above has a layer spacing of lithium cobaltate lattice due to the presence of different elements, such as the constant valence element in FIG. 4 replacing the cobalt site, if the valence ionic radius of the constant valence element Larger than cobalt ions, the layer spacing becomes larger; the doping of the valence element ions between the cobalt layer and the oxygen layer inevitably leads to a larger interlayer spacing; the layer spacing becomes larger as a change in the c-axis size in the lattice structure, using Brooke The D8Advance X-ray diffractometer measures the c-axis size of doped lithium cobaltate, and its size varies.

(The lithium cobalt oxide c-axis size without doping is

) or 0.02% to 0.3%.

Also proposed in the present invention is a structure in which a doped lithium cobaltate surface is coated and modified, and the surface coating layer comprises an inorganic solid electrolyte material or a high voltage active material. Whether it is substitution doping or gap doping, it is to stabilize the layered structure of lithium cobaltate itself and avoid the frequent transition of lithium cobaltate between layered hexagonal system and spinel monoclinic system. By coating the surface of the lithium cobaltate material, the side reaction between the electrolyte and the lithium cobaltate can be reduced to reduce the polarization effect, thereby suppressing the occurrence of the chemical reaction and the dissolution of the cobalt, thereby ensuring the stability of the lithium cobaltate layer structure. . The side reaction between the electrolyte and lithium cobaltate occurs because ions or electrons are concentrated at the interface of the electrolyte/active material, and the electrolyte reacts directly with the high concentration of tetravalent cobalt ions on the surface of the positive electrode to initiate decomposition reaction. And causing the dissolution of cobalt ions in the electrolyte and releasing the gas.

The surface coating can be coated by a dry method or a wet method: the coating needs to have good stability, that is, it cannot be dissolved in the electrolyte system and is stable at a high potential, and also has good electrons and lithium ions. Conductivity, which facilitates the conduction of electrons in the electrode and the diffusion of lithium ions, reduces the polarization effect of the interface, prevents the direct contact of the electrolyte with the high concentration of tetravalent cobalt ions on the surface of the positive electrode, initiates the decomposition reaction and causes the cobalt ions to be electrolyzed. Dissolution in the liquid, thereby stabilizing the structure after delithiation, and improving the electrochemical performance of lithium cobaltate. In the present invention, in order to achieve the above object, the material of the surface coating layer used is Li _γ1 Mc _γ2 O _γ3 , including an inorganic solid electrolyte material or a high voltage active material, wherein Mc is Cr, Co, Ni, Cu, Mn. , one or more of Ti, Zr, Hf, La, Nb, In, W, Ta, Ba, Te, Y, Sb, P, γ1, γ2 and γ3 may be any positive number, but need to satisfy the valence Distribution, Mc can have a variety of options.

Several possible forms of surface coatings are listed below: Li ₂ MgTiO ₄ , LiLaTiO ₄ , Li ₆ La ₃ Zr _1.5 W _0.5 O ₁₂ , Li _7.06 La ₃ Zr _1.94 Y _1.06 O ₁₂ , LiNiMnO ₄ , LiCo _0.5 Ni _0.5 O ₂ , LiCoPO ₄ , LiNiPO ₄ , Li _1+x (Ni _0.5 Mn _0.5 ) _1-x O ₂ (0≤x≤0.06), Li _1+x (Ni _z Co _1-2z Mn _z ) _1-x O ₂ (0 ≤ x ≤ 0.06, 0 ≤ z ≤ 0.5) and the like.

Through the above two kinds of doping and surface coating, the lithium cobaltate cathode material αLi _γ1 Mc _γ2 O _γ3 ·βLi _1+z Co _1-xy Ma _x Mb _y O which is doped and surface-coated co-modified is finally obtained. ₂ (Generally, 0<α≤0.08, 0.92≤β≤1, 0≤x≤0.01, 0≤y≤0.01, -0.05≤z≤0.08; preferably, 0<α≤0.05, 0.95≤β≤1 , 0.0005 ≤ x ≤ 0.005, 0.0005 ≤ y ≤ 0.005, -0.01 ≤ z ≤ 0.03), so that the modified lithium cobaltate cathode material can work at 4.45V and above to meet the battery requirements.

In an embodiment of the present invention, a method for preparing a lithium cobaltate cathode material doped and surface-coated co-modified is further provided, the method comprising:

Step (1): using a controlled crystallization method, a molar ratio, an appropriate amount of a cobalt source and a compound containing a constant valence element Ma, and an aqueous solution containing a Co ion and a constant valence element Ma ion, mixed with a complexing agent solution and a precipitating agent solution The reaction is crystallized while stirring, and the pH of the reaction system is controlled to 6 to 12, and after crystallization, centrifugal filtration is performed to obtain a carbonate or hydroxide of a cobalt doped with a constant valence element Ma;

Step (2): molar ratio, taking an appropriate amount of the compound containing the variable element Mb and the cobalt carbonate or hydroxide doped with the constant-valent element Ma obtained after the step (1), and uniformly mixed, and placed in a horse boiling furnace or Temperature sintering is performed in a sintering furnace, and then the product is pulverized to obtain an oxide precursor of Co co-doped with Ma and Mb;

Step (3): molar ratio, the oxide precursor of Co co-doped with Ma and Mb obtained in step (2) is mixed with a lithium source and ground uniformly, and placed in a horse boiling furnace or a sintering furnace for temperature sintering, and then The product is pulverized to obtain a doped lithium cobaltate Li _1+z Co _1-xy Ma _x Mb _y O ₂ co-doped with Ma and Mb (generally, 0≤x≤0.01, 0≤y≤0.01, - 0.05≤z≤0.08; preferably, 0.0005≤x≤0.005, 0.0005≤y≤0.005, -0.01≤z≤0.03);

Step (4): using a solid phase coating synthesis method, a molar ratio, a lithium source and a compound containing the element Mc, and a doped lithium cobaltate Li _1+z Co _1-xy Ma _x obtained after the step (3) Mb _y O _{2 is} stirred and mixed uniformly, and is sintered in a horse boiling furnace or a sintering furnace, and then the product is pulverized to obtain a lithium cobaltate cathode material αLi _γ1 Mc _γ2 O _γ3 which is doped with surface phase doping and surface coating. βLi _1+z Co _1-xy Ma _x Mb _y O ₂ (generally, 0 < α ≤ 0.08, 0.92 ≤ β ≤ 1; preferably, 0 < α ≤ 0.05, 0.95 ≤ β ≤ 1).

In addition, the step (4) may be replaced by: using a liquid phase coating synthesis method, a molar ratio, a lithium source and a compound containing the element Mc, and a doped lithium cobaltate Li1+zCo1-x obtained after the step (3). -yMaxMbyO2 is stirred and mixed uniformly. After the powder is dried, it is sintered in a horse boiling furnace or a sintering furnace, and then the product is pulverized to obtain a lithium cobaltate cathode material αLi _γ1 Mc _γ2 which is doped with surface phase doping and surface coating. O _γ3 ·βLi _1+z Co _1-xy Ma _x Mb _y O ₂ (generally, 0 < α ≤ 0.08, 0.92 ≤ β ≤ 1; preferably, 0 < α ≤ 0.05, 0.95 ≤ β ≤ 1).

Optionally, in the step (1), the cobalt source is one or more of cobalt acetate, cobalt oxalate, cobalt nitrate, cobalt sulfate, and cobalt chloride;

Optionally, in the step (1), the constant valence element Ma is one or more of Al, Ga, Hf, Mg, Sn, Zn, and Zr;

Optionally, in the step (1), the compound containing the constant valence element Ma is one selected from the group consisting of nitrates, oxalates, acetates, fluorides, chlorides, sulfates, and the like containing Ma or a plurality of; more preferably one or more selected from the group consisting of sulfates, nitrates, and acetates of Ma, such as: aluminum oxalate, aluminum nitrate, magnesium oxalate, magnesium nitrate, zirconium oxalate, zirconium nitrate, zinc oxalate , zinc nitrate, gallium nitrate, gallium fluoride, tin sulfide, etc.;

Optionally, in the step (1), the Co ion concentration in the aqueous solution containing the Co ion and the constant valence element Ma ion is 0.5-2.0 mol/L; more optionally, the Co ion and the constant-valent element Ma ion are included. The concentration of Co ions in the aqueous solution is 0.8 to 1.5 mol/L.

Optionally, in the step (1), the precipitant solution is a strong alkali solution, a carbonate solution, an oxalic acid or an oxalate solution.

Optionally, in the step (1), the complexing agent solution is an ammonia water or an aminohydroxy acid salt solution.

Optionally, in the step (1), when the aqueous solution containing the Co ion and the constant valence element Ma ion is mixed with the precipitant solution, the flow is controlled by the cocurrent flow control method; and the flow rate of the parallel flow control does not exceed 200 L/ h, the stirring speed does not exceed 200 rpm, and the crystallization temperature does not exceed 100 °C.

Optionally, in the step (1), the crystallization is repeated for 4 to 8 times in a continuous reaction.

Optionally, in the step (2), the variable element Mb is one or more of Ni, Mn, V, Mo, Nb, Cu, Fe, In, W, Cr; and/or

Optionally, in the step (2), the compound containing the variable-valent element Mb is one selected from the group consisting of oxides, hydroxides, carbonates, nitrates, oxalates, acetates, and the like containing Mb. Or more than one; more optionally selected from one or more of nitrates and acetates containing Mb, such as: nickel nitrate, nickel oxide, nickel hydroxide, nickel oxyhydroxide, nickel carbonate, nickel oxalate, manganese oxide , manganese carbonate, manganese oxalate, manganese nitrate, molybdenum oxide, molybdenum hydroxide, molybdenum carbonate, molybdenum oxalate, molybdenum nitrate, cerium oxide, cerium hydroxide, cerium oxalate, cerium nitrate, copper oxide, copper hydroxide, copper nitrate, acetic acid Copper, copper chloride, iron oxide, iron hydroxide, iron nitrate, iron oxalate, iron chloride, indium oxide, indium hydroxide, indium chloride, tungsten oxide, tungsten fluoride, chromium oxide, chromium hydroxide, chromium carbonate , chromium oxalate, chromium nitrate and the like.

Optionally, in the step (2), the temperature sintering temperature is 800-1000 ° C, the sintering time is 4-10 h; more optionally, the temperature sintering temperature is 900-950 ° C, and the sintering time is 6-8 h.

Optionally, in the step (3), the lithium source is selected from the group consisting of lithium-containing compounds and compositions thereof, and may be selected from the group consisting of lithium hydroxide, lithium nitrate, lithium carbonate, lithium oxalate, lithium acetate, lithium oxide, and citric acid. One or more of lithium, more preferably selected from lithium carbonate and lithium hydroxide;

Optionally, in the step (3), the temperature sintering temperature is 950 to 1100 ° C, and the sintering time is 8 to 16 h; more optionally, the temperature sintering temperature is 1020 to 1080 ° C, and the sintering time is 10 to 14 h.

Optionally, in the step (4), the element Mc is Cr, Co, Ni, Cu, Mn, Ti, Zr, Hf, La, Nb, In, W, Ta, Ba, Te, Y, Sb, P. One or several of them;

Optionally, in the step (4), the compound containing the element Mc is one or more of an oxide, a hydroxide, a carbonate, a nitrate, an oxalate, an acetate, etc. containing Mc. ;

Optionally, in the step (4), the temperature sintering temperature is 850 to 1050 ° C, and the sintering time is 8 to 16 hours; more optionally, the temperature sintering temperature is 900 to 1000 ° C, and the sintering time is 10 to 14 hours.

In the above preparation method, by using the controlled crystallization method, the constant-valent element and the cobalt source are uniformly distributed in the liquid system, so that the doping element is uniformly distributed, the reaction is complete, and the formed crystal structure is stable. In the step (2), while the temperature is sintered in the step (1) and the mixture of the valence elements, the step (1) of the loose structure shrinks into a densely fused and stabilized doped precursor Co ₃ O ₄ , which is more than cobalt ions. The more stable constant-valent element ions occupy the cobalt site and enhance the structural stability of the precursor Co ₃ O ₄ . At the same time, the variable-valent element ions have higher energy during temperature sintering and can enter the gap of the lattice structure to form The gap is doped to play a role of buffering or releasing stress in a high voltage cycle to stabilize the crystal structure.

In the strong oxidizing atmosphere of the charge and discharge process, Co ³⁺ will oxidize to Co ⁴⁺ and dissolve, and the valence element ions will not change in the valence state at the cobalt position, thereby maintaining the lithium ion transport channel and the lithium cobaltate layer structure. Stable; the elemental ions are doped through the gap, enter the cobalt and oxygen gaps, and are ionically bonded to the negatively charged CoO ₂ bulk layer. On the one hand, in the oxidizing atmosphere, the valence element ions are preferentially oxidized over Co ³⁺ . Therefore, the occurrence of Co ³⁺ oxidation is delayed. On the other hand, when the valence element is oxidized, the ionic radius changes due to the loss of electrons, thereby improving the lattice fit, and alleviating or releasing the stress generated by the skeleton change of the layered structure. To ensure the integrity of the skeleton of the layered structure and maintain the stability of the lithium ion transmission channel.

In another embodiment of the present invention, there is also provided a method for preparing a lithium cobaltate cathode material doped with a surface coating and co-modified, the method comprising:

Step (1): using a controlled crystallization method, a molar ratio, an appropriate amount of a cobalt source and a compound containing a constant valence element Ma, and an aqueous solution containing a Co ion and a constant valence element Ma ion, mixed with a complexing agent solution and a precipitating agent solution The reaction is crystallized while stirring, and the pH of the reaction system is controlled to 6 to 12, and after crystallization, centrifugal filtration is performed to obtain a carbonate or hydroxide of a cobalt doped with a constant valence element Ma;

Step (2): temperature-decomposing the cobalt carbonate or hydroxide of the constant-valent element Ma doped after the step (1), and then pulverizing the decomposition product to obtain a precursor of the constant-doped element Ma doping Body Co ₃ O ₄ ; molar ratio, take an appropriate amount of the compound containing the variable element Mb, the constant-content element Ma-doped precursor Co ₃ O ₄ and the lithium source are stirred and mixed uniformly, and placed in a horse boiling furnace or a sintering furnace for temperature sintering. The product is then pulverized to obtain a doped lithium cobaltate Li _1+z Co _1-xy Ma _x Mb _y O ₂ co-doped with Ma and Mb (generally, 0 _{≤ x ≤} 0.01, 0 _{≤ y ≤} 0.01) , -0.05 ≤ z ≤ 0.08; preferably, 0.0005 ≤ x ≤ 0.005, 0.0005 ≤ y ≤ 0.005, -0.01 ≤ z ≤ 0.03);

Step (3): using a solid phase coating synthesis method, a molar ratio, a lithium source and a compound containing the element Mc, and a doped lithium cobaltate Li _1+z Co _1-xy Ma _x obtained after the step (2) Mb _y O _{2 is} stirred and mixed uniformly, and is sintered in a horse boiling furnace or a sintering furnace, and then the product is pulverized to obtain a lithium cobaltate cathode material αLi _γ1 Mc _γ2 O _γ3 · βLi ₁ doped and surface-coated co-modified. _+z Co _1-xy Ma _x Mb _y O ₂ (generally, 0 < α ≤ 0.08, 0.92 ≤ β ≤ 1; preferably, 0 < α ≤ 0.05, 0.95 ≤ β ≤ 1).

It should be noted that step (3) can be replaced by: liquid phase coating synthesis method, molar ratio, lithium source and compound containing element Mc and doped lithium cobaltate obtained after step (2) Li _1+z Co _1-xy Ma _x Mb _y O _{2 is} stirred and mixed uniformly. After the powder is dried, it is placed in a horse boiling furnace or a sintering furnace for temperature sintering, and then the product is pulverized to obtain doping and surface coating co-modification. Lithium cobaltate cathode material αLi _γ1 Mc _γ2 O _γ3 ·βLi _1+z Co _1-xy Ma _x Mb _y O ₂ (generally, 0<α≤0.08, 0.92≤β≤1; optional, 0<α ≤ 0.05, 0.95 ≤ β ≤ 1).

Optionally, in the step (1), the cobalt source is one or more of cobalt acetate, cobalt oxalate, cobalt nitrate, cobalt sulfate, and cobalt chloride;

Optionally, in the step (1), the constant valence element Ma is one or more of Al, Ga, Hf, Mg, Sn, Zn, and Zr;

Optionally, in the step (1), the compound containing the constant valence element Ma is one selected from the group consisting of nitrates, oxalates, acetates, fluorides, chlorides, sulfates, and the like containing Ma or a plurality of; more preferably one or more selected from the group consisting of sulfates, nitrates, and acetates of Ma, such as: aluminum oxalate, aluminum nitrate, magnesium oxalate, magnesium nitrate, zirconium oxalate, zirconium nitrate, zinc oxalate , zinc nitrate, gallium nitrate, gallium fluoride, tin sulfide, etc.;

Optionally, in the step (1), the Co ion concentration in the aqueous solution containing the Co ion and the constant valence element Ma ion is 0.5-2.0 mol/L; more optionally, the Co ion and the constant-valent element Ma ion are included. The concentration of Co ions in the aqueous solution is 0.8 to 1.5 mol/L.

Optionally, in the step (1), the precipitant solution is a strong alkali solution, a carbonate solution, an oxalic acid or an oxalate solution.

Optionally, in the step (1), the complexing agent solution is an ammonia water or an aminohydroxy acid salt solution.

Optionally, in the step (1), when the aqueous solution containing the Co ion and the constant valence element Ma ion is mixed with the precipitant solution, the flow is controlled by the cocurrent flow control method; and the flow rate of the parallel flow control does not exceed 200 L/ h, the stirring speed does not exceed 200 rpm, and the crystallization temperature does not exceed 100 °C.

Optionally, in the step (1), the crystallization is repeated for 4 to 8 times in a continuous reaction.

Optionally, in the step (2), the variable element Mb is one or more of Ni, Mn, V, Mo, Nb, Cu, Fe, In, W, Cr;

Optionally, in the step (2), the compound containing the variable-valent element Mb is one selected from the group consisting of oxides, hydroxides, carbonates, nitrates, oxalates, acetates, and the like containing Mb. Or more than one; more optionally selected from one or more of nitrates and acetates containing Mb, such as: nickel nitrate, nickel oxide, nickel hydroxide, nickel oxyhydroxide, nickel carbonate, nickel oxalate, manganese oxide , manganese carbonate, manganese oxalate, manganese nitrate, molybdenum oxide, molybdenum hydroxide, molybdenum carbonate, molybdenum oxalate, molybdenum nitrate, cerium oxide, cerium hydroxide, cerium oxalate, cerium nitrate, copper oxide, copper hydroxide, copper nitrate, acetic acid Copper, copper chloride, iron oxide, iron hydroxide, iron nitrate, iron oxalate, iron chloride, indium oxide, indium hydroxide, indium chloride, tungsten oxide, tungsten fluoride, chromium oxide, chromium hydroxide, chromium carbonate , chromium oxalate, chromium nitrate and the like.

Optionally, in the step (2), the temperature sintering temperature is 800-1000 ° C, the sintering time is 4-10 h; more optionally, the temperature sintering temperature is 900-950 ° C, and the sintering time is 6-8 h.

Optionally, in the step (3), the element Mc is Cr, Co, Ni, Cu, Mn, Ti, Zr, Hf, La, Nb, In, W, Ta, Ba, Te, Y, Sb, P. One or several of them;

Optionally, in the step (3), the compound containing the element Mc is one or more of an oxide, a hydroxide, a carbonate, a nitrate, an oxalate, an acetate, etc. containing Mc. ;

Optionally, in the step (3), the temperature sintering temperature is 850 to 1050 ° C, and the sintering time is 8 to 16 hours; more optionally, the temperature sintering temperature is 900 to 1000 ° C, and the sintering time is 10 to 14 hours.

The present invention will be further described in detail below with reference to the embodiments, but the embodiments of the present invention are not limited thereto.

Example 1:

A lithium cobaltate cathode material formed by doping Al, Ni and coating Li ₂ MgTiO ₄ with lithium cobaltate, and having a molecular formula of 0.005Li ₂ MgTiO ₄ ·0.995LiCo _0.996 Al _0.003 Ni _0.001 O ₂ , the preparation method thereof comprises The following steps:

(1) Dissolve CoSO ₄ and Al ₂ (SO ₄ ) _{3 in} deionized water, and arrange a mixed salt solution having a molar ratio of Co:Al=99.6:0.3, and the concentration of Co ²⁺ in the mixed salt solution is 1.25 mol/ L; using concentrated ammonia water and distilled water to form a complexing agent solution at a volume ratio of 1:10; using 1.2 mol/L sodium carbonate solution as a precipitating agent solution; injecting a solvent solution of 1/3 of the solvent into the reaction kettle, Under the action of strong agitation and inert gas protection, the above mixed salt solution, complexing agent solution and precipitant solution are simultaneously injected into the reaction vessel by cocurrently controlling the flow rate, and the flow rate of the flow control is not more than 200 L/ h, stirring at the same time, the stirring speed does not exceed 200 rpm, and control the pH value of the reaction system is 6-12, and the temperature of the reaction kettle is controlled at 70-80 ° C during the reaction; the doping element Al in the reaction system is monitored in real time during the reaction. And the liquid phase ion concentration of Co; the continuous reaction is repeated 4 times and then subjected to centrifugal filtration to obtain a precursor cobalt salt doped with Al;

(2) molar ratio Co:Ni=99.6:0.1 Weigh a certain amount of nickel acetate, and mix and mix the Al-doped precursor cobalt salt obtained in step (1), and place it in a horse-boiling furnace at 900 ° C for sintering. The time is 8h, and then the sintered product is pulverized to obtain an Al, Ni co-doped Co ₃ O ₄ precursor with uniform particle distribution;

(3) The molar ratio Li:Co=100:99.6 weighs a certain amount of lithium carbonate, and the Al and Ni co-doped Co ₃ O ₄ precursor obtained after the step (2) is stirred and uniformly mixed, and placed in a horse boiling furnace. At 1050 ° C, the sintering time was 12 h, and then the sintered product was pulverized to obtain Al and Ni co-doped doped lithium cobalt oxide LiCo _0.996 Al _0.003 Ni _0.001 O _{2 with} uniform particle distribution;

(4) molar ratio Li:Mg:Ti:LiCo _0.996 Al _0.003 Ni _0.001 O ₂ =0.25:0.5:0.5:99.5 Weigh a certain amount of lithium carbonate, magnesium oxide, titanium oxide and the step (3) LiCo _0.996 Al _0.003 Ni _0.001 O _{2 was} stirred and mixed uniformly, placed in a horse boiling furnace at 950 ° C, and the sintering time was 12 h. Then the sintered product was pulverized to obtain a lithium cobaltate cathode material doped with surface coating and co-modified 0.005. Li ₂ MgTiO ₄ ·0.995LiCo _0.996 Al _0.003 Ni _0.001 O ₂ .

图6(a)为制备的钴酸锂正极材料的扫描电镜图及图6(b)为制备的钴酸锂正极材料的透射电镜图。图6(a)中可以看到，所得钴酸锂正极材料为表面圆润的椭球形颗粒，图6(b)中能明显看到颗粒外表面的包覆层，厚度约为10nm，在本实施例中，此包覆层为Li₂MgTiO₄。图7为制备的钴酸锂正极材料的粒度分布图，可以看到，所得钴酸锂正极材料的颗粒粒径分布集中，D50为16μm。图8和图9则为本正极材料的首次充放电曲线及循环曲线，根据所示的测试结果，可以看出该正极材料在室温条件下，电压范围为3.0～4.6V时，该低极化型高电压钴酸锂正极材料具有很高的放电比容量和优异的循环稳定性，首次放电克容量达到224mAh/g，首次充放电效率为96.6％，循环50次之后，容量保持率大于95％。该材料之所以表现出优异的循环稳定性，是因为以下几个方面的：通过不变价元素的取代掺杂取代钴位，在强氧化氛围中不发生氧化，维持钴氧主体层板的稳定性和锂离子传输通道的通畅；变价元素的间隙掺杂，一方面，在氧化性氛围里变价元素离子优先于Co³⁺发生氧化，从而推迟Co³⁺氧化的发生，另一方面当变价元素离子发生氧化时，其离子半径会因为失去电子产生变化，从而改善晶格适配性，来缓解或释放层状结构的骨架变化产生的应力，保证层状结构的骨架完整，维持锂离子传输通道的稳定。The prepared lithium cobaltate cathode material 0.005Li ₂ MgTiO ₄ ·0.995LiCo _0.996 Al _0.003 Ni _0.001 O ₂ was tested for physical properties and constant current charge and discharge. Figure 5 shows the X-ray diffraction spectrum obtained by Bruker D8 Advance X-ray diffractometer. In the figure, the layer spacing of the lithium cobaltate can be calculated from the diffraction angle of the (003) peak, that is, the c-axis dimension of the lithium cobaltate. The diffraction angle (2theta) corresponding to the (003) peak in Fig. 5 is 18.91°, and the c-axis size can be obtained by calculation. for

Fig. 6(a) is a scanning electron micrograph of the prepared lithium cobaltate cathode material, and Fig. 6(b) is a transmission electron micrograph of the prepared lithium cobaltate cathode material. It can be seen from Fig. 6(a) that the obtained lithium cobaltate cathode material is an ellipsoidal particle having a rounded surface, and the coating layer on the outer surface of the particle can be clearly seen in Fig. 6(b), and has a thickness of about 10 nm. In this example, the coating layer is Li ₂ MgTiO ₄ . Fig. 7 is a particle size distribution diagram of the prepared lithium cobaltate positive electrode material. It can be seen that the obtained lithium cobaltate positive electrode material has a particle size distribution concentrated, and a D50 of 16 μm. Fig. 8 and Fig. 9 show the first charge and discharge curve and cycle curve of the positive electrode material. According to the test results shown, it can be seen that the positive electrode material has a low voltage when the voltage range is 3.0 to 4.6V at room temperature. The high-voltage lithium cobaltate cathode material has high discharge specific capacity and excellent cycle stability. The first discharge capacity reaches 224 mAh/g, the first charge-discharge efficiency is 96.6%, and the capacity retention rate is greater than 95% after 50 cycles. . The reason why the material exhibits excellent cycle stability is due to the following aspects: substitution of cobalt sites by substitution doping of invariant elements, no oxidation in a strong oxidizing atmosphere, and maintenance of stability of the cobalt-oxygen main layer plate. And the patency of the lithium ion transport channel; the gap doping of the valence element, on the one hand, the valence element ions oxidize preferentially over Co ³⁺ in the oxidizing atmosphere, thereby delaying the occurrence of Co ³⁺ oxidation, and on the other hand, when the valence element ions When oxidation occurs, the ionic radius changes due to loss of electrons, thereby improving lattice fit, to relieve or release the stress caused by the skeleton change of the layered structure, to ensure the integrity of the skeleton of the layered structure, and to maintain the lithium ion transport channel. stable.

Embodiment 2:

A lithium cobaltate cathode material is formed by doping Al, Cr and coating LiLaTiO ₄ with lithium cobaltate, and has a molecular formula of 0.005LiLaTiO ₄ ·0.995Li _1.03 Co _0.995 Al _0.004 Cr _0.001 O ₂ , and the preparation method comprises the following steps :

(1) Dissolve CoSO ₄ and Al ₂ (SO ₄ ) _{3 in} deionized water, and arrange a mixed salt solution having a molar ratio of Co:Al=99.5:0.4, and the concentration of Co ²⁺ in the mixed salt solution is 1.25 mol/ L; using concentrated ammonia water and distilled water to form a complexing agent solution at a volume ratio of 1:10; using 1.2 mol/L sodium carbonate solution as a precipitating agent solution; injecting a solvent solution of 1/3 of the solvent into the reaction kettle, Under the action of strong agitation and inert gas protection, the above mixed salt solution, complexing agent solution and precipitant solution are simultaneously injected into the reaction vessel by cocurrently controlling the flow rate, and the flow rate of the flow control is not more than 200 L/ h, stirring at the same time, the stirring speed does not exceed 200 rpm, and control the pH value of the reaction system is 6-12, and the temperature of the reaction kettle is controlled at 70-80 ° C during the reaction; the doping element Al in the reaction system is monitored in real time during the reaction. And the liquid phase ion concentration of Co; the continuous reaction is repeated 4 times and then subjected to centrifugal filtration to obtain a precursor cobalt salt doped with Al;

(2) molar ratio Co:Cr=99.5:0.1 Weigh a certain amount of chromium oxide, and mix and mix the Al-doped precursor cobalt salt obtained in step (1), and place it in a horse-boiling furnace at 900 ° C for sintering. The time is 8h, and then the sintered product is pulverized to obtain an Al, Cr co-doped Co ₃ O ₄ precursor with uniform particle distribution;

(3) The molar ratio Li:Co=103:99.5 weighs a certain amount of lithium carbonate, and the Al and Cr co-doped Co ₃ O ₄ precursor obtained after the step (2) is stirred and uniformly mixed, and placed in a horse boiling furnace. At 1050 ° C, the sintering time is 12h, and then the sintered product is pulverized to obtain Al, Cr co-doped doped lithium cobalt oxide Li _1.03 Co _0.995 Al _0.004 Cr _0.001 O _{2 with} uniform particle distribution;

(4) molar ratio Li:La:Ti:Li _1.03 Co _0.995 Al _0.004 Cr _0.001 O ₂ =0.5:0.5:0.5:99.5 Weigh a certain amount of lithium carbonate, cerium oxide, titanium oxide and the step (3) The obtained Li _1.03 Co _0.995 Al _0.004 Cr _0.001 O _{2 was} stirred and mixed uniformly, placed in a horse boiling furnace at 950 ° C, and the sintering time was 12 h, and then the sintered product was pulverized to obtain a doped and surface-coated co-modified cobalt acid. Lithium positive electrode material 0.005LiLaTiO ₄ ·0.995Li _1.03 Co _0.995 Al _0.004 Cr _0.001 O ₂ .

Embodiment 3:

A lithium cobaltate cathode material formed by doping Al, Ni and coating LiCo _0.5 Ni _0.5 O ₂ with lithium cobaltate, and having a molecular formula of 0.005LiCo _0.5 Ni _0.5 O ₂ ·0.995LiCo _0.996 Al _0.003 Ni _0.001 O ₂ , The preparation method comprises the following steps:

(1) Dissolve CoSO ₄ and Al ₂ (SO ₄ ) _{3 in} deionized water, and arrange a mixed salt solution having a molar ratio of Co:Al=99.6:0.3, and the concentration of Co ²⁺ in the mixed salt solution is 1.25 mol/ L; using concentrated ammonia water and distilled water to form a complexing agent solution at a volume ratio of 1:10; using 1.2 mol/L sodium carbonate solution as a precipitating agent solution; injecting a solvent solution of 1/3 of the solvent into the reaction kettle, Under the action of strong agitation and inert gas protection, the above mixed salt solution, complexing agent solution and precipitant solution are simultaneously injected into the reaction vessel by cocurrently controlling the flow rate, and the flow rate of the flow control is not more than 200 L/ h, stirring at the same time, the stirring speed does not exceed 200 rpm, and control the pH value of the reaction system is 6-12, and the temperature of the reaction kettle is controlled at 70-80 ° C during the reaction; the doping element Al in the reaction system is monitored in real time during the reaction. And the liquid phase ion concentration of Co; the continuous reaction is repeated 4 times and then subjected to centrifugal filtration to obtain a precursor cobalt salt doped with Al;

(2) molar ratio Co:Ni=99.6:0.1 Weigh a certain amount of nickel acetate, and mix and mix the Al-doped precursor cobalt salt obtained in step (1), and place it in a horse-boiling furnace at 900 ° C for sintering. The time is 8h, and then the sintered product is pulverized to obtain an Al, Ni co-doped Co ₃ O ₄ precursor with uniform particle distribution;

(3) The molar ratio Li:Co=100:99.6 weighs a certain amount of lithium carbonate, and the Al and Ni co-doped Co ₃ O ₄ precursor obtained after the step (2) is stirred and uniformly mixed, and placed in a horse boiling furnace. At 1050 ° C, the sintering time was 12 h, and then the sintered product was pulverized to obtain Al and Ni co-doped doped lithium cobalt oxide LiCo _0.996 Al _0.003 Ni _0.001 O _{2 with} uniform particle distribution;

(4) molar ratio Li:Co:Ni:LiCo _0.996 Al _0.003 Ni _0.001 O ₂ =0.5:0.25:0.25:99.5 Weigh a certain amount of lithium carbonate, cobalt carbonate, nickel acetate and the step (3) LiCo _0.996 Al _0.003 Ni _0.001 O _{2 was} stirred and mixed uniformly, placed in a horse boiling furnace at 950 ° C, and the sintering time was 12 h. Then the sintered product was pulverized to obtain a lithium cobaltate cathode material doped with surface coating and co-modified 0.005. LiCo _0.5 Ni _0.5 O ₂ ·0.995LiCo _0.996 Al _0.003 Ni _0.001 O ₂ .

Embodiment 4:

A lithium cobaltate cathode material, which is doped with Al, Mn by lithium cobaltate and coated with Li _1.06 (Ni _0.425 Co _0.15 Mn _0.425 ) _0.94 O ₂ , and has a molecular formula of 0.005Li _1.06 (Ni _0.425 Co _0.15 Mn _0.425 ) _0.94 O2·0.995Li _1.02 Co _0.994 Al _0.004 Mn _0.002 O ₂ , the preparation method comprises the following steps:

(1) Dissolving CoSO ₄ and Al ₂ (SO ₄ ) _{3 in} deionized water, and configuring a mixed salt solution having a molar ratio of Co:Al=99.4:0.4, and the concentration of Co ²⁺ in the mixed salt solution is 1.25 mol/ L; using concentrated ammonia water and distilled water to form a complexing agent solution at a volume ratio of 1:10; using 1.2 mol/L sodium carbonate solution as a precipitating agent solution; injecting a solvent solution of 1/3 of the solvent into the reaction kettle, Under the action of strong agitation and inert gas protection, the above mixed salt solution, complexing agent solution and precipitant solution are simultaneously injected into the reaction vessel by cocurrently controlling the flow rate, and the flow rate of the flow control is not more than 200 L/ h, stirring at the same time, the stirring speed does not exceed 200 rpm, and control the pH value of the reaction system is 6-12, and the temperature of the reaction kettle is controlled at 70-80 ° C during the reaction; the doping element Al in the reaction system is monitored in real time during the reaction. And the liquid phase ion concentration of Co; the continuous reaction is repeated 4 times and then subjected to centrifugal filtration to obtain a precursor cobalt salt doped with Al;

(2) The Al-doped precursor cobalt salt obtained in the step (1) is subjected to pyrolysis at 900 ° C in a horse-boiling furnace, and the decomposition time is 6 h, and then the decomposition product is pulverized to obtain Al having uniform particle distribution. a doped Co ₃ O ₄ precursor;

(3) molar ratio Li:Co:Mn=102:99.4:0.2 Weigh a certain amount of lithium carbonate and manganese acetate, and the Al-doped Co ₃ O ₄ precursor obtained after the step (2) is stirred and mixed uniformly. It was placed in a horse boiling furnace at 1050 ° C, and the sintering time was 12 h. Then, the sintered product was pulverized to obtain Al and Mn co-doped doped lithium cobalt oxide Li _1.02 Co _0.994 Al _0.004 Mn _0.002 O _{2 with} uniform particle distribution;

(4) molar ratio Li: Ni: Co: Mn: Li _1.02 Co _0.994 Al _0.004 Mn _0.002 O ₂ = 0.53: 0.2125: 0.075: 0.2125: 99.5 Weigh a certain amount of lithium carbonate, nickel acetate, cobalt carbonate, manganese acetate And the Li _1.02 Co _0.994 Al _0.004 Mn _0.002 O ₂ prepared after the step (3) is stirred and uniformly mixed, placed in a horse boiling furnace at 950 ° C, and the sintering time is 12 h, and then the sintered product is pulverized to obtain a doping and surface coating. Co-modified lithium cobaltate cathode material 0.005Li _1.06 (Ni _0.425 Co _0.15 Mn _0.425 ) _0.94 O ₂ ·0.995Li _1.02 Co _0.994 Al _0.004 Mn _0.002 O ₂ .

As can be seen from the above, the present invention has been studied intensively in combination with the practical application of academia and industry. Through the improvement of the process, a lithium cobaltate cathode material and a preparation method thereof have been proposed, and the lithium cobaltate cathode material includes doped cobalt acid. Lithium and a surface coating layer covering the doped lithium cobaltate. The doping-doping variable-valent element and the constant-valent element in the invention improve the structural stability and cycle performance of the lithium cobaltate cathode material, wherein the doped variable elements are Ni, Mn, V, Mo, Nb, Cu, Fe, In, W, Cr, the constant valence elements are Al, Ga, Hf, Mg, Sn, Zn, Zr. On the one hand, the constant valence element replaces the cobalt site by substitution doping, instead of cobalt ion, to ensure that the skeleton-cobalt site of the layered structure is not distorted by oxidation, and the layered structure of the lithium cobaltate positive electrode material can be stabilized under high voltage use. On the other hand, the valence element is doped by a gap, and is filled between the cobalt ion layer and the oxygen ion layer of the main layer of the lithium cobaltate lattice structure, specifically, the valence element ions are filled in a cobalt ion and a The three oxygen ions on the oxygen ion layer are in a tetrahedral space formed by the apex, or the three cobalt ions filled on the one oxygen ion and one cobalt ion layer are in a tetrahedral space composed of vertices. In the process of charge and discharge, not only the oxidation of Co ³⁺ occurs in the oxidizing atmosphere, but also the occurrence of Co ³⁺ oxidation can be delayed, and when the valence element ions are oxidized, the ionic radius changes due to the loss of electrons, thereby improving the crystal. The lattice adaptability is to relieve or release the stress generated by the skeleton change of the layered structure, and achieve the purpose of stabilizing the lithium cobaltate layered structure. The invention combines the principle and process of phase transformation of a lithium cobaltate layer structure in a high voltage scene, fully exerts the advantages of each doping element, and significantly improves the comprehensive performance of the cathode material.

Further, the present invention proposes coating a surface coating layer on the surface of the doped lithium cobaltate, the coating layer comprising an inorganic solid electrolyte material and a high voltage active material, the coating layer being used as a stable cathode material and electrolyte The interface ensures that lithium cobaltate does not dissolve in the electrolyte under high voltage, and can have good electron and lithium ion conductivity, which is beneficial to the conduction of electrons in the electrode and the diffusion of lithium ions, and reduces the positive electrode material and electrolyte. The polarization effect at the interface stabilizes the structure after delithiation and improves the electrochemical performance of lithium cobaltate. The high-voltage lithium cobaltate cathode material prepared by the method of doping and surface coating co-modification can be used at a higher charge cut-off voltage, thereby improving the energy density of the lithium ion battery and having an excellent cycle life.

Further, the present invention is prepared by a liquid phase-solid phase method, which combines the advantages of the two methods. The doping element is uniformly mixed with the particles of the cobalt compound in the liquid phase system, and can be uniformly diffused into the particles during the sintering process. The product prepared by the process has excellent crystal quality, high tap density, good processing performance, chemical composition close to the theoretical value, and excellent layered structure.

Further, the present invention comprehensively considers the controlled crystallization method for preparing a substituted doped precursor and solid phase sintering to synthesize a high voltage lithium cobaltate product; the existing equipment can be used for large scale industrial production.

In another embodiment of the present invention, a lithium cobaltate cathode material doped and surface-coated co-modified is provided, the cathode material comprising doped lithium cobalt oxide and a surface coating layer, and the general chemistry thereof The composition is, for example, αLi _γ1 Mc _γ2 O _γ3 ·βLi _1+z Co _1-xy Ma _x Mb _y O ₂ (generally, 0<α≤0.08, 0.92≤β≤1; 0≤x≤0.01, 0≤y≤0.01 , -0.05 ≤ z ≤ 0.08; γ1, γ2, and γ3 may be any positive number, but need to satisfy the distribution of valence).

Wherein, the doped lithium cobaltate has the formula of Li _1+z Co _1-xy Ma _x Mb _y O ₂ (generally, 0≤x≤0.01, 0≤y≤0.01, -0.05≤z≤0.08; preferably , 0.0005 ≤ x ≤ 0.005, 0.0005 ≤ y ≤ 0.005, -0.01 ≤ z ≤ 0.03), Ma is one or more of the doped valence elements Al, Ga, Hf, Mg, Sn, Zn, Zr Mb is one or more of the doped variable elements Ni, Mn, V, Mo, Nb, Cu, Fe, In, W, Cr.

Wherein, the chemical composition of the surface coating layer is Li _γ1 Mc _γ2 O _γ3 , wherein Mc is generally a metal element and a transition metal element such as Cr, Co, Ni, Cu, Mn, Ti, Zr, Hf, La, Nb, In One or more of W, Ta, Ba, Te, Y, Sb, P, γ1, γ2 and γ3 may be any positive number, but need to satisfy the distribution of valence.

It is to be understood that the above doped lithium cobalt oxide and its cladding structure are not necessarily used in combination, and the doped lithium cobalt oxide collectively can be used independently as a separate material and can be used independently without a coating structure.

The present invention also provides a lithium ion battery, as shown in FIG. 10, comprising a positive electrode sheet, a negative electrode sheet and a separator disposed between the positive and negative electrode sheets, and an electrolyte, wherein the positive electrode sheet includes a cathode current collector and distribution The positive electrode active material on the positive electrode current collector is a positive electrode active material layer using a high-voltage lithium cobaltate positive electrode material doped and surface-coated and co-modified as described above. The high voltage lithium cobaltate has an active capacity greater than 190 mAh/g. The present invention also provides an electronic device using the above lithium ion battery. The electronic device may be a mobile terminal, including a casing, a working circuit, and a charging port mounted on the casing, wherein the mobile terminal includes the lithium ion battery, and the lithium ion battery And supplying power to the working circuit and charging through the charging port.

Claims (17)

A lithium cobaltate cathode material, characterized in that the lithium cobaltate cathode material comprises doped lithium cobalt oxide, and the substance constituting the doped lithium cobaltate has the formula Li _1+z Co _1-xy Ma _x Mb _y O ₂ : Wherein, 0≤x≤0.01, 0≤y≤0.01, -0.05≤z≤0.08; The Ma is a doped constant valence element, and the Ma is at least one of Al, Ga, Hf, Mg, Sn, Zn, and Zr; The Mb is a doped variable element, and the Mb is at least one of Ni, Mn, V, Mo, Nb, Cu, Fe, In, W, Cr; The lattice of the doped lithium cobaltate comprises a bulk layer composed of a cobalt ion layer and an oxygen ion layer, and a lithium ion layer distributed on both sides of the bulk layer, the bulk layer further comprising the blend A heterogeneous element Ma and a variable element Mb for replacing a cobalt ion in the bulk layer. The lithium cobaltate cathode material according to claim 1, wherein the variable element Mb is filled between a cobalt ion layer and an oxygen ion layer of the bulk layer. The lithium cobaltate cathode material according to claim 2, wherein the variable element Mb is located in a tetrahedral space formed by apex of three oxygen ions on a cobalt ion and an oxygen ion layer, or The variable element Mb is located in a tetrahedral space formed by vertices of three cobalt ions on an oxygen ion and a cobalt ion layer. The lithium cobaltate cathode material according to any one of claims 1 to 3, wherein the constant valence element Ma is ionically bonded to the main body layer, and the main body layer includes oxygen ion layers sequentially arranged. a cobalt ion layer and an oxygen ion layer, the cobalt ion layer being located between the two oxygen ion layers. The lithium cobaltate cathode material according to any one of claims 1 to 4, wherein a lattice c-axis size of the lithium cobaltate cathode material varies within a range of

The lithium cobaltate cathode material according to any one of claims 1 to 5, wherein 0.0005 ≤ x ≤ 0.005. The lithium cobaltate cathode material according to any one of claims 1 to 6, which is characterized in that it is 0.0005 ≤ y ≤ 0.005. The lithium cobaltate cathode material according to any one of claims 1 to 7, which is characterized in that -0.01 ? z ? 0.03. The lithium cobaltate cathode material according to any one of claims 1 to 8, wherein the lithium cobaltate cathode material further comprises a surface coating layer covering the doped lithium cobaltate, the surface The cladding layer includes an inorganic solid electrolyte material having a general formula of Li _γ1 Mc _γ2 O _γ3 : Wherein Mc is at least one of Ti, Zr, Hf, La, Nb, In, W, Ta, Ba, Te, Y, Sb, and the γ1, γ2, and γ3 satisfy the formula γ1+A*γ2=2 * Any positive number of γ3, where A is the valence of Mc. The lithium cobaltate cathode material according to any one of claims 1 to 9, wherein the lithium cobaltate cathode material further comprises a surface coating layer covering the doped lithium cobaltate, the surface The cladding layer comprises a high voltage active material having the general formula Li _γ1 Mc _γ2 O _γ3 : Wherein Mc is at least one of Cr, Co, Ni, Cu, Mn, P, and the γ1, γ2, and γ3 are any positive numbers satisfying the formula γ1+A*γ2=2*γ3, and the A is Mc The valence. A method for producing the lithium cobaltate cathode material according to any one of claims 1 to 10, characterized in that the method comprises: The cobalt source, the compound containing the constant valence element Ma is configured as an aqueous solution; wherein the Ma is at least one of Al, Ga, Hf, Mg, Sn, Zn, Zr; Mixing the aqueous solution, the complex solution and the precipitant solution to cause the aqueous solution to react with the complex solution and the precipitant solution to obtain a carbonate or hydroxide of the Ma-doped cobalt; The obtained cobalt-doped cobalt carbonate or hydroxide is sintered at a temperature of 900 to 1000 ° C to obtain a Ma-doped precursor Co ₃ O ₄ , wherein the sintering time is 4 ～ 10h; The lithium source, the Mb-containing compound and the Ma-doped precursor Co ₃ O ₄ are sintered at a temperature of 950 to 1100 ° C for 8 to 16 hours to obtain a doped lithium cobalt oxide co-doped with Ma and Mb. ; A method for producing the lithium cobaltate cathode material according to any one of claims 1 to 10, characterized in that the method comprises: The cobalt source, the compound containing the constant valence element Ma is configured as an aqueous solution; wherein the Ma is at least one of Al, Ga, Hf, Mg, Sn, Zn, Zr; Mixing the aqueous solution with the complex solution and the precipitant solution to cause the aqueous solution, the complex solution and the precipitant solution to react and crystallize to obtain the carbonate or hydroxide of the Ma-doped cobalt; Mixing the obtained cobalt or hydroxide of the doped cobalt with a compound containing a valence element Mb; wherein the Mb is Ni, Mn, V, Mo, Nb, Cu, Fe, In, W At least one of Cr; The mixture obtained by mixing is sintered at a temperature of 800 to 1000 ° C for 4-10 hours to obtain an oxide precursor of Co co-doped with Ma and Mb; The obtained oxide precursor of Co co-doped with Ma and Mb is mixed with a lithium source; The mixture of the oxide precursor and the lithium source is sintered at a temperature of 950 to 1100 ° C for 8 to 16 hours to obtain the doped lithium cobalt oxide co-doped with the Ma and Mb. The method according to claim 11 or 12, wherein the method further comprises: The lithium source, the compound containing the element Mc, and the obtained doped lithium cobalt oxide doped with the Ma and Mb are mixed and sintered at a temperature of 850 to 1050 ° C for 8 to 16 hours to obtain the lithium cobaltate positive electrode. a material, wherein the Mc is at least one of Cr, Co, Ni, Cu, Mn, Ti, Zr, Hf, La, Nb, In, W, Ta, Ba, Te, Y, Sb, P. The method according to claim 12 or 13, wherein the aqueous solution is mixed with a complex solution and a precipitant solution to cause the aqueous solution to react with the complex solution and the precipitant solution to obtain crystallization. The carbonate or hydroxide of the Ma-doped cobalt includes: The aqueous solution containing Co ions and the constant-valent element Ma ions is mixed with the precipitating agent solution by means of cocurrent flow control; wherein the flow rate of the parallel flow control does not exceed 200 L/h, the stirring speed does not exceed 200 rpm, and the crystallization temperature does not exceed 100. °C. A method according to any one of claims 12 to 14, wherein The cobalt source is at least one of cobalt acetate, cobalt oxalate, cobalt nitrate, cobalt sulfate, and cobalt chloride; The compound containing a constant valence element Ma is at least one of nitrate, oxalate, acetate, fluoride, chloride, and sulfate containing Ma; The concentration of Co ions in the aqueous solution containing Co ions and the constant-valent element Ma ions is 0.5-2.0 mol/L; The precipitant solution is a strong alkali solution, a carbonate solution, an oxalic acid or an oxalate solution; The complexing agent solution is an ammonia water or an aminohydroxy acid salt solution; The compound containing a variable-valent element Mb is at least one selected from the group consisting of oxides, hydroxides, carbonates, nitrates, oxalates, and acetates containing Mb; The lithium source is at least one of lithium hydroxide, lithium nitrate, lithium carbonate, lithium oxalate, lithium acetate, lithium oxide, and lithium citrate; or The compound containing the element Mc is at least one of an oxide, a hydroxide, a carbonate, a nitrate, an oxalate, and an acetate containing Mc. A lithium ion battery comprising a positive electrode sheet, a negative electrode sheet, an electrolyte, and a positive and negative electrode sheet In the separator, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer distributed on the positive electrode current collector, wherein the positive electrode active material layer is made of the cobalt according to any one of claims 1 to 10. A lithium acid positive electrode material is used as a positive electrode active material. A mobile terminal includes a casing, a working circuit, and a charging port mounted on the casing, wherein the mobile terminal comprises the lithium ion battery according to claim 16, and the lithium ion battery is used for The working circuit provides electrical energy and is charged through the charging port.

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