CN107819126A - A kind of positive electrode of metal halide battery and preparation method thereof - Google Patents

Abstract

The invention provides a kind of positive electrode of metal halide battery, is that two-dimensional sheet material graphene and/or MXene are introduced in the positive electrode of existing metal halide battery, to substitute the part in excessive electroactive metal.Due to the introducing of the substituent, reduce the addition of electroactive metal in positive pole component, and because the substituent has good thermal conductivity, it ensure that in the good electrical and thermal conductivity performance of middle 150 250 DEG C of anode intracavitary of low temperature, so as to improve the effective rate of utilization of electroactive metal；Also reduce the interparticle contact probability of electroactive metal simultaneously, it is suppressed that the misgrowth of electroactive metal particle, alkali halide in cyclic process, so as to significantly improve the cycle life of battery.

Description

A kind of cathode material of metal halide battery and preparation method thereof

technical field

The invention relates to the technical field of metal halide batteries, in particular to a positive electrode material of a metal halide battery and a preparation method thereof.

Background technique

Metal halide batteries, including Sodium-Metal Halide Batteries and the like, are useful in many energy storage applications. In addition to the anode, this type of battery also includes a positive electrode (or called a cathode) that supplies/receives electrons during charging/discharging of the battery. Wherein the positive electrode material comprises at least one electroactive metal and at least one alkali metal halide.

Sodium-Metal Halide Batteries (Sodium-Metal Halide Batteries) is a new type of secondary battery with low cost, safety and environmental protection, and high specific energy, in which β”-Al ₂ O ₃ (sodium ion fast ion conductor) is a solid electrolyte, Other sodium molten salts are liquid electrolytes, the negative electrode material is molten sodium, and the positive electrode material is metal chlorides (such as NiCl ₂ and FeCl ₂ , etc.) and corresponding metals.

Sodium-nickel chloride battery (Zero Emission Battery Research Activities, ZEBRA) is a kind of sodium-metal chloride battery, with β”-Al ₂ O ₃ as the solid electrolyte diaphragm and sodium tetrachloroaluminate as the molten liquid electrolyte, Molten _sodium is used as the negative electrode and NiCl2 and excess Ni are used as the positive electrode. In addition to the sodium-nickel chloride system, ferric chloride, zinc chloride, etc. can also be used as active materials to form a similar ZEBRA battery.

In order to improve the conductivity and prolong the service life of metal halide batteries, the traditional method mainly adopts the addition of excess electroactive metal element in the positive electrode material. For example, in a sodium-nickel chloride battery, the amount of nickel required in theory should be 0.5 times that of NaCl, and the mass ratio is about 0.5, but in practical applications, in order to ensure the conductivity of the positive component and a certain The cycle life, the amount of nickel is usually 1.4 times the mass of NaCl. However, during the charging and discharging process, the actual utilization rate of the electroactive metal element is not increased, resulting in a low utilization rate of the electroactive metal element. In addition, excessive electroactive metal elements will increase the contact probability of metal particles in a medium-high temperature environment (usually 250-300 ° C), resulting in abnormal growth of electroactive metal particles and alkali metal halides during cycling, thereby reducing the battery life. cycle life.

For this reason, the patent CN103178245A uses carbon black to partially replace Ni, which has a certain inhibitory effect on nickel and optimizes battery performance. However, due to the limited conductivity of carbon black, a large amount of addition is required. Patent CN103718348A introduces micron-level pure iron and pure aluminum metal components into the positive electrode powder composition, and at the same time granulates the positive electrode powder into uniform micron-sized spheres, which increases the specific surface area, improves the electrical conductivity and the metal effective utilization rate.

Contents of the invention

The present invention aims to provide a positive electrode material for a metal halide battery, wherein the effective utilization rate of the electroactive metal is high, and the metal halide battery comprising the positive electrode material has high energy density and power density, good cycle life, and good battery stability Etc.

In order to achieve the above technical purpose, the inventors introduced two-dimensional sheet materials with high specific surface area, such as graphene, two-dimensional layered transition metal carbides or carbonitrides (MXenes), into the positive electrode materials of metal halide batteries. One or two of them are used to replace part of the excess electroactive metal to obtain a new type of positive electrode composition.

That is, the technical solution provided by the present invention is a positive electrode material for a metal halide battery, which contains at least one electroactive metal and at least one alkali metal halide, and is characterized in that: the positive electrode material also contains a two-dimensional sheet Materials, such as one or both of graphene, two-dimensional layered transition metal carbides or carbonitrides.

The two-dimensional layered transition metal carbides or carbonitrides, i.e. MXenes, can generally be represented by M _n+1 X _n T _z , where M refers to transition metals (such as Ti, Zr, Hf, V, Nb, Ta , Cr, Sc, etc.), X refers to C or/and N, n is generally 1-3, and T _z refers to surface groups (such as O ^2- , OH ^- , F ^- , NH ₃ , NH ₄ ⁺ , etc.). At present, MXenes are generally derived from ternary layered cermets M _n+1 AX _n phase (M is a transition metal element, A is a main group element, X is C and/or N, n is generally 1 to 3, referred to as MAX phase ), which is obtained by extracting weaker A-site elements (such as Al, Si, etc. atoms) in the MAX phase. Similar to graphene, MXenes have excellent electrical and thermal conductivity, high specific surface area, etc. Moreover, MXenes naturally have a multilayer "accordion-like" structure, which is not easy to agglomerate; at the same time, the abundant groups on its surface can serve as suitable ligands for iron/nickel/cobalt ions.

The MXenes include, but are not limited to, one or a combination of two or more of Ti ₂ CT _x , Ti ₃ C ₂ T _x , Ti ₃ CNT _x .

The electroactive metals include but are not limited to one or more of titanium, vanadium, niobium, molybdenum, nickel, cobalt, chromium, copper, manganese, silver, antimony, cadmium, tin, lead, iron, zinc, etc. The combination.

The alkali metal halides include, but are not limited to, at least one halide of sodium, potassium, lithium, etc.

The molar ratio of the electroactive metal to the alkali metal halide is preferably 0.6-1.2, more preferably 0.8-1.1, even more preferably 1.05.

In the positive electrode material, the mass sum of graphene and MXenes accounts for 1%-20% of the total mass of the positive electrode material.

The present invention also provides a method for preparing the above metal halide battery positive electrode material, comprising the following steps:

providing a powder comprising at least one electroactive metal and at least one alkali metal halide; and

One or both of graphene and MXenes are uniformly mixed with the powder, and the graphene and MXenes are dispersed in the powder.

In summary, the present invention introduces two-dimensional flake material graphene and/or MXenes into the positive electrode material of the existing metal halide battery to replace part of the excess electroactive metal, and obtains a new positive electrode composition, It has the following beneficial effects:

(1) The amount of electroactive metal used is reduced; and, since both graphene and MXene belong to two-dimensional sheet materials, both of them have high specific surface area and excellent electrical and thermal conductivity, and provide electron conduction in positive electrode materials. The "high-speed pathway" is thus conducive to the high electrical and thermal conductivity of the battery. Even in the range of 150-250°C, the battery can still ensure high energy density and power density, thus improving the effective utilization of electroactive metals;

(2) Due to the introduction of graphene and MXene, the content of electroactive metals in the positive electrode material is reduced, thus reducing the contact probability of electroactive metal particles, and suppressing the abnormality of electroactive metal particles and alkali metal halides during cycling growth, thereby significantly improving the cycle life of the battery, and solving the problem of low cycle life and stability of the existing metal halide batteries.

Therefore, the metal halide battery using the positive electrode material of the present invention as the positive electrode material has the advantages of high energy density and power density, good cycle life, and good battery stability.

Detailed ways

The present invention will be described in further detail below in conjunction with the examples. It should be pointed out that the following examples are intended to facilitate the understanding of the present invention, but do not limit it in any way.

Example 1:

In this embodiment, the preparation of positive electrode material is as follows:

(1) Mix ultrafine Ni and NaCl according to the molar ratio of 0.6, grind in alcohol, then add an appropriate amount of binder PVA or PVP, and pore-forming agent ammonium carbonate or ammonium bicarbonate, spray granulation, under 2mpa-5mpa After the preforming of the tablet, it is placed in a hydrogen atmosphere and calcined at a rate of 100°C/h to 700°C, and kept for 1h to obtain NaCl-Ni powder.

(2) Grinding the graphene to a particle size of 10 micrometers to 100 micrometers, and then keeping the temperature at 150° C. for 6 hours in a closed container with an inert atmosphere to obtain conductive ceramic powder.

(3) Physically mix NaCl-Ni powder, conductive ceramic powder and other additives by ball milling, wherein the mass ratio of NaCl-Ni powder to conductive ceramic powder is 10:1, so that the conductive ceramic powder is dispersed in the NaCl-Ni powder, Obtain positive electrode powder.

The positive electrode powder prepared above is added to the positive electrode cavity of the battery, then injected with molten NaAlCl ₄ electrolyte and packaged, and then packaged with the negative electrode of the battery and the shell to obtain a sodium-metal chloride battery.

Example 2:

(1) Mix ultrafine NiO and NaCl according to the molar ratio of 1.05, grind them in alcohol, then add an appropriate amount of binder PVA or PVP, pore-forming agent ammonium carbonate or ammonium bicarbonate, spray granulation, and press down at 2mpa-5mpa After the sheet is preformed, it is placed in a hydrogen atmosphere and calcined at a rate of 100°C/h to 700°C, and kept for 1h to obtain NaCl-Ni powder.

(2) Grinding the porous two-dimensional sheet-shaped conductive ceramic Ti ₂ C to a particle size of 10 microns to 100 microns, and then keeping the temperature at 150° C. for 6 hours in an airtight container with an inert atmosphere to obtain conductive ceramic powder.

(3) Physically mix NaCl-Ni powder, conductive ceramic powder and other additives by ball milling, wherein the mass ratio of NaCl-Ni powder to conductive ceramic powder is 5:1, so that the conductive ceramic powder is dispersed in the NaCl-Ni powder, Obtain positive electrode powder.

The positive electrode powder prepared above is added to the positive electrode cavity of the battery, then injected with molten NaAlCl ₄ electrolyte and packaged, and then packaged with the negative electrode of the battery and the shell to obtain a sodium-metal chloride battery.

Example 3:

(1) Mix superfine nickel oxalate and NaCl according to the molar ratio of 1.2, grind in alcohol, then add an appropriate amount of binder PVA or PVP, and pore-forming agent ammonium carbonate or ammonium bicarbonate, spray granulation, at 2mpa-5mpa After the lower tablet is preformed, it is placed in a hydrogen atmosphere and calcined at a rate of 100°C/h to 700°C, and kept for 1h to obtain NaCl-Ni powder.

(2) Grinding graphene and porous two-dimensional sheet-shaped conductive ceramic Ti ₂ C to a particle size of 10 microns to 100 microns, and then keeping the temperature at 150° C. for 6 hours in an inert atmosphere sealed container to obtain conductive ceramic powder.

(3) Physically mix NaCl-Ni powder, conductive ceramic powder and other additives by ball milling, wherein the mass ratio of NaCl-Ni powder to conductive ceramic powder is 15:1, so that the conductive ceramic powder is dispersed in the NaCl-Ni powder, Obtain positive electrode powder.

The positive electrode powder prepared above is added to the positive electrode cavity of the battery, then injected with molten NaAlCl ₄ electrolyte and packaged, and then packaged with the negative electrode of the battery and the shell to obtain a sodium-metal chloride battery.

The above-mentioned embodiments have systematically and detailedly described the technical solutions of the present invention. It should be understood that the above-mentioned examples are only specific embodiments of the present invention, and are not intended to limit the present invention. Any modification, supplement or equivalent replacement made within the principle scope of the present invention shall be included in the protection scope of the present invention.

Claims (10)

1. A positive electrode material for a metal halide battery, comprising at least one electroactive metal and at least one alkali metal halide, characterized in that: the positive electrode material also includes two-dimensional sheet material graphene, MXenes One or two. 2. The positive electrode material for metal halide batteries according to claim 1, characterized in that: said MXenes include one or more of Ti ₂ CT _x , Ti ₃ C ₂ T _x , Ti ₃ CNT _x The combination. 3. The positive electrode material of a metal halide battery as claimed in claim 1, wherein said electroactive metal comprises titanium, vanadium, niobium, molybdenum, nickel, cobalt, chromium, copper, manganese, silver, antimony, One or a combination of two or more of cadmium, tin, lead, iron, and zinc. 4. The positive electrode material of a metal halide battery according to claim 1, wherein the alkali metal halide comprises at least one halide of sodium, potassium and lithium. 5. The positive electrode material of a metal halide battery according to claim 1, characterized in that: the molar ratio of the electroactive metal to the alkali metal halide is 0.6-1.2. 6. The positive electrode material of a metal halide battery as claimed in claim 1, characterized in that: the molar ratio of the electroactive metal to the alkali metal halide is 0.8-1.1. 7. The positive electrode material of a metal halide battery as claimed in claim 1, wherein the molar ratio of the electroactive metal to the alkali metal halide is 1.05. 8. The positive electrode material for metal halide batteries according to claim 1, characterized in that: in the positive electrode material, the mass sum of graphene and MXenes accounts for 1%-20% of the total mass of the positive electrode material. 9. The method for preparing the positive electrode material of the metal halide battery according to any one of claims 1 to 8, characterized in that: comprising the steps of: providing a powder comprising at least one electroactive metal and at least one alkali metal halide; and One or both of graphene and MXenes are uniformly mixed with the powder, and the graphene and MXenes are dispersed in the powder. 10. A metal halide battery, the cathode material of which is the material according to any one of claims 1 to 8.