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WO2025014088A1 - Électrode positive et batterie rechargeable la comprenant - Google Patents

Électrode positive et batterie rechargeable la comprenant Download PDF

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Publication number
WO2025014088A1
WO2025014088A1 PCT/KR2024/007185 KR2024007185W WO2025014088A1 WO 2025014088 A1 WO2025014088 A1 WO 2025014088A1 KR 2024007185 W KR2024007185 W KR 2024007185W WO 2025014088 A1 WO2025014088 A1 WO 2025014088A1
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WIPO (PCT)
Prior art keywords
active material
positive electrode
silicon carbide
cathode
electrode active
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PCT/KR2024/007185
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English (en)
Korean (ko)
Inventor
김시열
김해성
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Kchem Biz Inc
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Kchem Biz Inc
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Priority claimed from KR1020230090283A external-priority patent/KR102672777B1/ko
Priority claimed from KR1020230090284A external-priority patent/KR102603798B1/ko
Priority claimed from KR1020230090282A external-priority patent/KR102672779B1/ko
Application filed by Kchem Biz Inc filed Critical Kchem Biz Inc
Publication of WO2025014088A1 publication Critical patent/WO2025014088A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a cathode and a secondary battery including the cathode.
  • lithium secondary batteries with high discharge voltage and energy density are widely used as an energy source for various mobile devices and electronic products.
  • Lithium transition metal composite oxides are used as positive electrode active materials for lithium secondary batteries, and among these, lithium cobalt composite metal oxides such as LiCoO 2 , which have high operating voltage and excellent capacity characteristics, are mainly used.
  • LiCoO 2 has low stability and is expensive, making it difficult to mass-produce lithium secondary batteries.
  • lithium manganese composite metal oxide, lithium iron phosphate, lithium nickel composite metal oxide, etc. have been developed as materials to replace LiCoO 2 .
  • lithium iron phosphate (LiFePO 4 ) with an olivine structure has a high volume density of 3.6 g/cm 3 and a theoretical capacity of approximately 170 mAh/g.
  • lithium iron phosphate (LiFePO 4 ) has low electrical conductivity, so when LiFePO 4 is used as a cathode active material, the internal resistance of the battery increases, which causes a problem in that the discharge capacity and life characteristics are reduced.
  • lithium secondary batteries are recently being used as power sources for hybrid and electric vehicles, and lithium secondary batteries with improved discharge capacity and excellent life characteristics are required.
  • the present invention provides a cathode having improved discharge capacity and life characteristics and excellent mechanical characteristics, and a secondary battery including the cathode.
  • a positive electrode according to the present invention comprises a current collector, and a positive electrode active material layer including a positive electrode active material and a conductive material, wherein the positive electrode active material comprises a core including a lithium iron phosphate-based active material, and silicon carbide formed on the core, the silicon carbide having a thickness of 5 nm to 100 nm, the conductive material comprising a single-walled carbon nanotube, and a weight ratio of the positive electrode active material: the single-walled carbon nanotube is 1:0.005 to 1:0.020.
  • the positive electrode active material layer may include at least one binder coagulant having a number average molecular weight of 30,000 g/mol to 80,000 g/mol selected from the group consisting of polyacrylamide, polyurethane, and polyacrylonitrile.
  • the metal nitride may include silicon nitride (Si 3 N 4 ).
  • a secondary battery according to the present invention comprises a cathode, an anode, and a separator interposed between the cathode and the anode, wherein the cathode comprises a current collector, and a cathode active material layer comprising a cathode active material and a conductive material, wherein the cathode active material comprises a core comprising a lithium iron phosphate-based active material, and silicon carbide formed on the core, wherein the silicon carbide has a thickness of 5 nm to 100 nm, and the conductive material comprises a single-walled carbon nanotube, and a weight ratio of the cathode active material: the single-walled carbon nanotube is 1:0.005 to 1:0.020.
  • a positive electrode according to the present invention comprises a current collector, a coating layer formed on the current collector and including an associative urethane-based thickener and a binder, and a positive electrode active material layer formed on the coating layer and including a lithium iron phosphate-based active material doped with sodium (Na) element, wherein the sodium element is doped in an amount of 800 ppm to 2,000 ppm relative to the total weight of the lithium iron phosphate-based active material.
  • the positive electrode active material layer may include at least one binder coagulant having a number average molecular weight of 30,000 g/mol to 80,000 g/mol selected from the group consisting of polyacrylamide, polyurethane, and polyacrylonitrile.
  • the weight average molecular weight of the associative urethane thickener may be 350,000 g/mol to 400,000 g/mol.
  • the positive electrode active material layer may include zirconium coated on the lithium iron phosphate-based active material.
  • a secondary battery according to the present invention comprises a cathode, an anode, and a separator interposed between the cathode and the anode, wherein the cathode comprises a current collector, a coating layer formed on the current collector and including an associative urethane-based thickener and a binder, and a cathode active material layer formed on the coating layer and including a lithium iron phosphate-based active material doped with sodium (Na) element, wherein the sodium element is doped in an amount of 800 ppm to 2,000 ppm relative to the total weight of the lithium iron phosphate-based active material.
  • Na sodium
  • the positive electrode according to the present invention includes a positive electrode active material including a lithium iron phosphate-based active material, and a coating layer formed on the lithium iron phosphate-based active material, wherein the coating layer includes sodium (Na) element and tantalum (Ta) element, and the total content of the sodium element and the tantalum element is 500 ppm to 2,000 ppm based on the total weight of the positive electrode active material, and the weight ratio of the sodium element: tantalum element included in the coating layer is 1:0.1 to 1:0.5.
  • a secondary battery according to the present invention comprises a cathode, an anode, and a separator interposed between the cathode and the anode, wherein the cathode comprises a cathode active material, wherein the cathode active material comprises a lithium iron phosphate-based active material, and a coating layer formed on the lithium iron phosphate-based active material, wherein the coating layer comprises sodium (Na) element and tantalum (Ta) element, and the total content of the sodium element and the tantalum element is 500 ppm to 2,000 ppm based on the total weight of the cathode active material, and a weight ratio of the sodium element:tantalum element included in the coating layer is 1:0.1 to 1:0.5.
  • the negative electrode includes a negative electrode active material layer including a negative electrode active material
  • the negative electrode active material may include at least one of titanium-tin-oxide doped with niobium and titanium-oxide doped with niobium.
  • the positive electrode according to the present invention includes silicon carbide of a specific thickness as a positive electrode active material and single-walled carbon nanotubes of a specific range as a conductive material, thereby improving the discharge capacity and life characteristics of a secondary battery and exhibiting excellent mechanical properties.
  • a positive electrode according to the present invention comprises a current collector, and a positive electrode active material layer including a positive electrode active material and a conductive material, wherein the positive electrode active material comprises a core including a lithium iron phosphate-based active material, and silicon carbide formed on the core, the silicon carbide having a thickness of 5 nm to 100 nm, the conductive material comprises a single-walled carbon nanotube, and a weight ratio of the positive electrode active material: the single-walled carbon nanotube is 1:0.005 to 1:0.020.
  • the cathode according to the present invention comprises a current collector.
  • the current collector may be stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum.
  • the thickness of the above-mentioned collector can be adjusted depending on the required product, and can be, for example, 10 ⁇ m to 500 ⁇ m, 10 ⁇ m to 300 ⁇ m, or 20 ⁇ m to 300 ⁇ m.
  • the above-described collector includes pores.
  • the total volume of the pores relative to the total volume of the collector may be 10% to 90%, 15% to 90%, 20% to 90%, 20% to 85%, 25% to 85%, 25% to 80%, or 30% to 80%.
  • the current density can be lowered without deteriorating the mechanical properties, so that the discharge capacity and life characteristics of the secondary battery can be improved.
  • a flame retardant layer containing a flame retardant can be formed on at least one surface of the above-mentioned collector. Flame retardancy is secured by the flame retardant layer, so that the spread of fire due to short-circuiting, overcharge, overdischarge, etc. of the secondary battery can be suppressed.
  • the flame retardant may include a halogen-based flame retardant, a phosphorus-based flame retardant, or an inorganic compound flame retardant.
  • the flame retardant may include an aliphatic halogen compound.
  • the flame retardant includes the aliphatic halogen compound, the flame retardant performance is further improved, and the compatibility between the positive electrode active material layers is increased, so that the deterioration of the discharge capacity and life characteristics of the secondary battery can be minimized.
  • the cathode according to the present invention may include a coating layer formed on the current collector and including an associative urethane-based thickener and a binder.
  • the coating layer may be formed between the current collector and the flame retardant layer.
  • the coating layer can improve the interfacial adhesion between the current collector and the flame retardant layer.
  • the coating layer can include an associative urethane-based thickener to suppress the occurrence of pinholes on the electrode surface.
  • the associative urethane-based thickener can strengthen the cohesion between positive electrode active materials.
  • the above associative urethane thickener may be referred to as a copolymer produced by synthesis between a polyalkylene glycol compound and a monomer or condensate referred to as an associative monomer of the alkyl, aryl or arylalkyl type consisting of, for example, a polyisocyanate and a hydrophobic terminal group.
  • the weight average molecular weight of the above-mentioned associative urethane-based thickener may be 200,000 g/mol to 500,000 g/mol, 250,000 g/mol to 500,000 g/mol, 250,000 g/mol to 450,000 g/mol, 300,000 g/mol to 450,000 g/mol, 350,000 g/mol to 450,000 g/mol, or 350,000 g/mol to 400,000 g/mol.
  • the coating layer can be prepared from a coating layer composition, and the associative urethane-based thickener can be included in an amount of 0.01 wt% to 3.00 wt%, 0.01 wt% to 1.00 wt%, or 0.1 wt% to 1.00 wt% based on the total weight of the coating layer composition.
  • the above coating layer may include a binder.
  • the binder may include styrene butadiene rubber (SBR).
  • SBR styrene butadiene rubber
  • the binder may further include one or more selected from the group consisting of polyvinylidene fluoride, polyvinyl alcohol, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butylene rubber, fluororubber, styrene (styrene monomer: SM), butadiene (BD), and butyl acrylate (BA).
  • SBR styrene butadiene rubber
  • the above positive electrode active material includes a core including a lithium iron phosphate-based active material.
  • the lithium iron phosphate-based active material may be a compound represented by the following chemical formula 1.
  • M is at least one element selected from the group consisting of Ni, Co, Mn, Ti, Ga, Cu, V, Nb, Zr, Ce, In, and Cu
  • Y is at least one element selected from the group consisting of F, S, and N
  • a, b, and x are -0.5 ⁇ a ⁇ 0.5, 0 ⁇ b ⁇ 0.1, and 0 ⁇ x ⁇ 0.5.
  • the above-described positive electrode active material includes silicon carbide formed on the core, and the thickness of the silicon carbide is 5 nm to 100 nm.
  • the silicon carbide can complement the mechanical properties of the positive electrode active material. When the thickness of the silicon carbide satisfies the above range, the mechanical properties can be improved without deteriorating the discharge capacity and life characteristics of the secondary battery.
  • the above-mentioned positive electrode active material may have a metal nitride component coated on the silicon carbide.
  • the metal nitride may include silicon nitride (Si 3 N 4 ).
  • the positive electrode active material layer according to the present invention may include a sodium (Na) element coated on the lithium iron phosphate-based active material.
  • a sodium (Na) element coated on the lithium iron phosphate-based active material.
  • the chemical stability of the surface of the lithium iron phosphate-based active material is improved, so that structural collapse of the lithium iron phosphate-based active material can be suppressed.
  • the sodium element is oxidized first compared to the metal included in the lithium iron phosphate-based active material, a side reaction between the lithium iron phosphate-based active material and the electrolyte can be suppressed, and thus an increase in resistance due to the movement of lithium ions can be prevented.
  • At least one selected from the group consisting of NaOH, Ba(OH) 2 , Na 2 CO 3 , NaCl, CH 3 COONa, Na 2 SO 4 , and NaNO 2 can be used.
  • the above-described positive electrode active material layer may include an aluminum (Al) element coated on the lithium iron phosphate-based active material.
  • Al aluminum
  • the chemical stability of the surface of the lithium iron phosphate-based active material is improved, so that structural collapse of the lithium iron phosphate-based active material can be suppressed and mechanical properties can be improved.
  • At least one selected from the group consisting of Al 2 O 3 , Al(OH) 3 , AlF 3 , AlBr 3 , AlPO 4 , AlCl 3 , Al(NO) 3 , Al(H 2 PO 4 ) 3 , and C 2 H 5 O 4 Al can be used.
  • the lithium iron phosphate-based active material may include a structure doped with a nitrogen (N) element.
  • the nitrogen element can improve the electrical conductivity of the secondary battery, thereby minimizing the phenomenon of the initial efficiency of the secondary battery being reduced.
  • the content of the nitrogen element relative to the total weight of the positive electrode active material layer may be included as 300 ppm to 10,000 ppm, 500 ppm to 5,000 ppm, 500 ppm to 4,000 ppm, 500 ppm to 3,000 ppm, 500 ppm to 2,000 ppm, or 500 ppm to 1,500 ppm.
  • the electrical conductivity of the secondary battery is improved, and the phenomenon of initial efficiency deterioration can be minimized.
  • the above lithium iron phosphate-based active material may include a conductive coating layer.
  • the conductive coating layer may include a carbon-based material.
  • the carbon-based material may be at least one selected from the group consisting of carbon black, carbon fibers or metal fibers, metal powder, conductive whiskers, conductive metals, activated carbon, polyphenylene derivatives, natural graphite, artificial graphite, Super-P, acetylene black, Ketjen black, channel black, finace black, lamp black, summer black, Denka black, aluminum powder, nickel powder, zinc oxide, gallium titanate, and titanium oxide.
  • the thickness of the conductive coating layer may be 1 nm to 500 nm, 1 nm to 300 nm, 1 nm to 250 nm, 1 nm to 200 nm, 5 nm to 200 nm, 5 nm to 100 nm, or 5 nm to 50 nm.
  • the content of carbon included in the conductive coating layer may be 1 wt% to 3 wt%, 1 wt% to 2.5 wt%, or 1 wt% to 2 wt% based on the total weight of the positive electrode active material layer.
  • the average particle diameter (D 50 ) of the lithium iron phosphate-based active material may be 0.3 ⁇ m to 10.0 ⁇ m, 0.3 ⁇ m to 9.0 ⁇ m, or 0.6 ⁇ m to 9.0 ⁇ m.
  • the average particle diameter (D 50 ) may be defined as a particle diameter at 50% of the particle diameter distribution of the positive electrode active material.
  • the average particle diameter (D 50 ) may be measured using a laser diffraction method. When the above range is satisfied, uniform mixing with the conductive material and the binder is possible, and process efficiency may be increased.
  • the specific surface area (BET) of the above lithium iron phosphate-based active material may be 30 m 2 /g or less, 20 m 2 /g or less, or 5 m 2 /g to 15 m 2 /g.
  • the specific surface area (BET) can be calculated from the nitrogen gas adsorption amount at liquid nitrogen temperature (77 K) using BELSORP-mino II of BEL Japan. When the above range is satisfied, the adhesion to the positive electrode current collector may not be reduced.
  • the tap density of the above lithium iron phosphate active material is 0.5 g/cm 3 or more, 0.6 g/cm 3 or more, or 0.6 g/cm 3 to It can be 1.5 g/cm 3 .
  • the tap density refers to the apparent density of the lithium iron phosphate-based active material powder, and can be measured using KYT-5000 from Seishin Co., Ltd. When the above range is satisfied, the packing density of the positive electrode is improved, the thickness of the positive electrode is improved to be thinner, and the breakage phenomenon of the positive electrode active material can be improved.
  • the above-mentioned positive electrode active material layer includes the above-mentioned positive electrode active material and conductive material.
  • the conductive material includes single-walled carbon nanotubes, and a weight ratio of the positive electrode active material: the single-walled carbon nanotubes is 1:0.005 to 1:0.020.
  • the conductive material can improve the conductivity of the lithium iron phosphate-based active material, and when the above range is satisfied, the relative ratio of the positive electrode active material is increased without lowering the electrical conductivity, so that the capacity of the secondary battery can be increased.
  • the above-described positive electrode active material layer may include a binder.
  • the binder may improve the bonding force between the lithium iron phosphate-based active material and the conductive material and the bonding force between the positive electrode active material layer and the positive electrode current collector.
  • the binder may be added in an amount of 1 to 30 parts by weight, 1 to 20 parts by weight, or 1 to 15 parts by weight based on 100 parts by weight of the lithium iron phosphate-based active material.
  • the type of the binder is not particularly limited, but for example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), fluororubber, styrene butadiene rubber (SBR, cellulose-based resin), etc. may be used.
  • the above positive electrode active material layer may include a conductive material and a binder.
  • the conductive agent can improve the conductivity of the lithium iron phosphate-based active material.
  • the conductive agent can be added in an amount of 1 to 40 parts by weight, 1 to 20 parts by weight, or 1 to 10 parts by weight based on 100 parts by weight of the lithium iron phosphate-based active material.
  • the type of the conductive agent is not particularly limited, but for example, Super-P, graphite, acetylene black, etc. can be used.
  • the above-described positive electrode active material layer may include at least one binder coagulant having a number average molecular weight of 30,000 g/mol to 80,000 g/mol selected from the group consisting of polyacrylamide, polyurethane, and polyacrylonitrile.
  • the binder coagulant may appropriately control the dispersibility of the binder, thereby suppressing the phenomenon in which the binder is concentratedly distributed on the current collector and the electrical conductivity is lowered.
  • a secondary battery according to the present invention comprises a cathode, an anode, and a separator interposed between the cathode and the anode, wherein the cathode comprises a current collector, and a cathode active material layer comprising a cathode active material and a conductive material, wherein the cathode active material comprises a core comprising a lithium iron phosphate-based active material, and silicon carbide formed on the core, wherein the silicon carbide has a thickness of 5 nm to 100 nm, and the conductive material comprises a single-walled carbon nanotube, and a weight ratio of the cathode active material: the single-walled carbon nanotube is 1:0.005 to 1:0.020.
  • the above positive electrode can be used in the same manner as the current collector, positive electrode active material layer, etc. described in relation to the above positive electrode.
  • the above secondary battery may include, in addition to the positive electrode of the present invention, an anode and a separator.
  • the anode may include an anode current collector and a negative electrode active material layer formed on the anode current collector.
  • the above negative electrode current collector is not particularly limited as long as it is conductive and does not cause a chemical change in the secondary battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used.
  • the bonding strength of the negative electrode active material can be strengthened by forming fine unevenness on the surface, and can be used in various forms such as a film, sheet, foil, net, porous body, foam, non-woven fabric, etc.
  • the above negative active material layer may include a negative active material.
  • the type of the above negative active material is not particularly limited, and a compound capable of reversible intercalation and deintercalation of lithium can be used.
  • a compound capable of reversible intercalation and deintercalation of lithium can be used.
  • carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, amorphous carbon, and high-crystalline carbon
  • metallic compounds capable of alloying with lithium such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, or Al alloy can be used.
  • Low-crystalline carbons include soft carbon and hard carbon
  • high-crystalline carbons include natural graphite, kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, mesophase pitch-based carbon microspheres, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch derived cokes.
  • the negative active material may also use a composite material including a metallic compound and a carbonaceous material, as needed.
  • the negative active material may include at least one of niobium-doped titanium-tin-oxide and niobium-doped titanium-oxide to suppress lithium dentride generation and improve the life characteristics of the secondary battery.
  • the above separator may be interposed between the cathode and the anode.
  • the separator is configured to prevent an electrical short circuit between the cathode and the anode and to allow ion flow.
  • the separator may include a porous polymer film or a porous non-woven fabric.
  • the porous polymer film may be configured as a single layer or multiple layers including a polyolefin polymer such as an ethylene polymer, a propylene polymer, an ethylene/butene copolymer, an ethylene/hexene copolymer, and an ethylene/methacrylate copolymer.
  • the porous non-woven fabric may include high-melting-point glass fibers and polyethylene terephthalate fibers.
  • the separator may be a high-heat-resistant separator (CCS; Ceramic Coated Separator) including ceramic.
  • the above positive electrode, negative electrode, and separator can be manufactured into an electrode assembly by a winding, lamination, folding, or zigzag stacking process.
  • the electrode assembly can be manufactured into a secondary battery according to the present invention by being provided with an electrolyte.
  • the secondary battery can be any one of a cylindrical shape using a can, a square shape, a pouch shape, and a coin shape, but is not limited thereto.
  • the electrolyte may be a non-aqueous electrolyte.
  • the electrolyte may include a lithium salt and an organic solvent.
  • the organic solvent may include at least one of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), methylpropyl carbonate (MPC), dipropyl carbonate (DPC), vinylene carbonate (VC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, sulfolane, gamma-butyrolactone, propylene sulfide, and tetrahydrofuran.
  • PC propylene carbonate
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • DMC dimethyl carbonate
  • EMC ethylmethyl carbonate
  • EMC ethylmethyl carbonate
  • MPC methylprop
  • a positive electrode slurry was prepared by adding ammonia water to a mixture of an aqueous solution containing iron sulfate (FeSO 4 ⁇ 7H 2 O), phosphoric acid (H 3 PO 4 ), and an antioxidant and a lithium aqueous solution (LiOH ⁇ H 2 O) to obtain a pH of 6. Thereafter, the positive electrode slurry was introduced at a constant rate under the conditions of 400 °C and 270 bar in a continuous process supercritical reactor to prepare a LiFePO 4 solution, and the LiFePO 4 solution was washed and filtered to obtain LiFePO 4 particles.
  • FeSO 4 ⁇ 7H 2 O iron sulfate
  • H 3 PO 4 phosphoric acid
  • LiOH ⁇ H 2 O lithium aqueous solution
  • the LiFePO 4 particles were reslurried and then mixed with 1 wt% of mesophase pitch based on the total weight of the slurry. Thereafter, the mixture was calcined at 1,200° C. for 12 hours in an inert atmosphere, so that 20 nm thick silicon carbide was formed on the surface of the LiFePO 4 particles. The formation and thickness of the silicon carbide were confirmed using TEM images.
  • the LiFePO 4 particles on which the silicon carbide was formed, single-walled carbon nanotubes, and polyvinylidene fluoride were mixed at a weight ratio of 98:0.5:1.5 in an N-methyl pyrrolidone solvent to manufacture a cathode active material.
  • a cathode active material was applied onto aluminum (Al) having a thickness of 15 ⁇ m and then dried. Thereafter, the cathode active material was rolled to form a cathode active material layer on the cathode current collector, thereby manufacturing a cathode.
  • An electrode assembly was manufactured by interposing a 25 ⁇ m thick polyethylene separator between an anode including TiNb 2 O 7 (TNO) as an anode active material and the manufactured anode, and then the electrode assembly was placed in a case, and an electrolyte solution containing 1 M LiPF 6 and 2.5 wt% vinyl carbonate mixed in a volume ratio of ethylene carbonate and methyl ethyl carbonate was injected into the case to manufacture a secondary battery.
  • TNO TiNb 2 O 7
  • a positive electrode slurry was prepared by adding ammonia water to a mixture of an aqueous solution containing iron sulfate (FeSO 4 ⁇ 7H 2 O), phosphoric acid (H 3 PO 4 ), and an antioxidant and a lithium aqueous solution (LiOH ⁇ H 2 O) to obtain a pH of 6. Thereafter, the positive electrode slurry was introduced at a constant rate under the conditions of 400 °C and 270 bar in a continuous process supercritical reactor to prepare a LiFePO 4 solution, and the LiFePO 4 solution was washed and filtered to obtain LiFePO 4 particles.
  • FeSO 4 ⁇ 7H 2 O iron sulfate
  • H 3 PO 4 phosphoric acid
  • LiOH ⁇ H 2 O lithium aqueous solution
  • the LiFePO 4 particles were first reslurried and then mixed with 1 wt% of mesophase pitch based on the total weight of the slurry. Thereafter, the mixture was calcined at 1,200° C. for 12 hours in an inert atmosphere, and silicon carbide having a thickness of 20 nm was formed on the surface of the LiFePO 4 particles. Thereafter, the LiFePO 4 particles on which the silicon carbide was formed were secondarily reslurried and then mixed with 1 wt% of silicon nitride (Si 3 N 4 ) based on the total weight of the slurry. Thereafter, the mixture was calcined at 400° C.
  • silicon nitride having a thickness of 10 nm was formed on the silicon carbide.
  • the formation and thickness of the silicon carbide and silicon nitride were confirmed using TEM images.
  • the above silicon carbide and silicon nitride-formed LiFePO 4 particles, single-walled carbon nanotubes, and polyvinylidene fluoride were mixed in a weight ratio of 98:0.5:1.5 in an N-methyl pyrrolidone solvent to manufacture a cathode active material.
  • a positive electrode and a secondary battery were manufactured by the same process as in Example 1 above.
  • a secondary battery was manufactured by the same process as Example 2, except that 1.5 wt% of silicon nitride (Si 3 N 4 ) was mixed instead of 1 wt% of silicon nitride (Si 3 N 4 ).
  • a secondary battery was manufactured by the same process as Example 1, except that instead of forming a 20 nm thick silicon carbide on the surface of the LiFePO 4 particles, a 5 nm thick silicon carbide was formed on the surface of the LiFePO 4 particles.
  • a secondary battery was manufactured by the same process as Example 1, except that instead of mixing the LiFePO 4 particles on which silicon carbide is formed, the single-walled carbon nanotubes, and polyvinylidene fluoride in a weight ratio of 98:0.5:1.5, the LiFePO 4 particles on which silicon carbide is formed, the single-walled carbon nanotubes, and polyvinylidene fluoride were mixed in a weight ratio of 98:1:1.
  • a secondary battery was manufactured by the same process as Example 1, except that instead of forming a 20 nm thick silicon carbide on the surface of the LiFePO 4 particles, an 80 nm thick silicon carbide was formed on the surface of the LiFePO 4 particles.
  • a secondary battery was manufactured by the same process as Example 1, except that instead of mixing the LiFePO 4 particles on which silicon carbide is formed, the single-walled carbon nanotubes, and polyvinylidene fluoride in a weight ratio of 98:0.5:1.5, the LiFePO 4 particles on which silicon carbide is formed, the single-walled carbon nanotubes, and polyvinylidene fluoride were mixed in a weight ratio of 98:1.2:0.8.
  • a 300 nm thick silicon carbide was formed on the surface of the LiFePO 4 particles instead of a 20 nm thick silicon carbide, and instead of mixing the LiFePO 4 particles on which the silicon carbide was formed, single-walled carbon nanotubes, and polyvinylidene fluoride in a weight ratio of 98:0.5:1.5, the LiFePO 4 particles on which the silicon carbide was formed, Super-b, and polyvinylidene fluoride were mixed in a weight ratio of 95:2:3, and a carbon-based material was used instead of TiNb 2 O 7 (TNO) as the negative electrode active material, with the exception that this was done by the same process as Example 1, to manufacture a secondary battery.
  • TNO TiNb 2 O 7
  • LiFePO 4 particles, single-walled carbon nanotubes, and polyvinylidene fluoride were mixed in a weight ratio of 95:0.5:1.5 in an N-methyl pyrrolidone solvent to prepare a cathode active material.
  • a secondary battery was manufactured by the same process as Example 1, except that a carbon-based material was used instead of TiNb 2 O 7 (TNO) as the negative active material.
  • TNO TiNb 2 O 7
  • Each of the secondary batteries manufactured in Examples 1 to 7 and Comparative Examples 1 to 2 was charged at a constant current of 0.1C rate in a voltage range of 2.5 V to 4.1 V versus lithium metal at room temperature, and the discharge capacity was obtained according to the increase in the current density during discharge, and the charge/discharge efficiency at each rate was calculated therefrom.
  • the current densities during discharge were 0.1C, 0.2C, 0.5C, 1C, and 2C rates, respectively.
  • the charge/discharge efficiency at 2C was calculated by Equation 1 below, and the results are shown in Table 1 below.
  • Each of the secondary batteries manufactured in Examples 1 to 7 and Comparative Examples 1 to 2 was charged and discharged at a constant current of 1C rate in a voltage range of 2.5 V to 4.1 V versus lithium metal at room temperature, while measuring the capacity retention ratio and the discharge capacity at the 300th cycle.
  • the capacity retention ratio at room temperature was calculated by Equation 2 below, and the results are shown in Table 1 below.
  • Capacity retention rate (%) [discharge capacity at the 300th cycle/discharge capacity at the 1st cycle] ⁇ 100
  • the invention provides improved discharge capacity and life-cycle characteristics and can be applied to a cathode having excellent mechanical characteristics and a secondary battery including the cathode.

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  • Battery Electrode And Active Subsutance (AREA)

Abstract

La présente invention concerne une électrode positive et une batterie rechargeable la comprenant. L'électrode positive comprend un collecteur de courant ; et une couche de matériau actif d'électrode positive contenant un matériau actif d'électrode positive et un matériau conducteur. Le matériau actif d'électrode positive comprend : un noyau contenant un matériau actif à base de phosphate de fer et de lithium ; et un carbure de silicium formé sur le noyau. L'épaisseur du carbure de silicium va de 5 à 100 nm. Le matériau conducteur comprend des nanotubes de carbone à simple paroi. Le rapport en poids du matériau actif d'électrode positive aux nanotubes de carbone à simple paroi est de 1:0,005 à 1:0,020.
PCT/KR2024/007185 2023-07-12 2024-05-28 Électrode positive et batterie rechargeable la comprenant Pending WO2025014088A1 (fr)

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KR1020230090283A KR102672777B1 (ko) 2023-07-12 2023-07-12 양극 및 이를 포함하는 이차 전지
KR10-2023-0090284 2023-07-12
KR1020230090284A KR102603798B1 (ko) 2023-07-12 2023-07-12 양극 및 이를 포함하는 이차 전지
KR10-2023-0090283 2023-07-12
KR1020230090282A KR102672779B1 (ko) 2023-07-12 2023-07-12 양극 및 이를 포함하는 이차 전지
KR10-2023-0090282 2023-07-12

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KR20160031782A (ko) * 2014-09-15 2016-03-23 (주)포스코켐텍 리튬 이차 전지용 음극 활물질, 이의 제조 방법, 및 이를 포함하는 리튬 이차 전지
KR20170130786A (ko) * 2016-05-19 2017-11-29 숭실대학교산학협력단 실리콘/실리콘 질화물 및 실리콘 카바이드 코어-쉘 복합체를 포함하는 탄소나노섬유 복합체 제조방법
KR20190072667A (ko) * 2016-11-14 2019-06-25 리락 솔루션즈, 인크. 코팅된 이온 교환 입자를 이용한 리튬 추출
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KR20130003069A (ko) * 2011-06-24 2013-01-09 삼성에스디아이 주식회사 복합양극활물질, 이를 포함하는 양극 및 리튬전지, 및 이의 제조방법
KR20150009116A (ko) * 2013-07-15 2015-01-26 (주)포스코켐텍 리튬 이차 전지용 전극 활물질, 이의 제조 방법, 이를 포함하는 전극, 및 상기 전극을 포함하는 리튬 이차 전지
KR20160031782A (ko) * 2014-09-15 2016-03-23 (주)포스코켐텍 리튬 이차 전지용 음극 활물질, 이의 제조 방법, 및 이를 포함하는 리튬 이차 전지
KR20170130786A (ko) * 2016-05-19 2017-11-29 숭실대학교산학협력단 실리콘/실리콘 질화물 및 실리콘 카바이드 코어-쉘 복합체를 포함하는 탄소나노섬유 복합체 제조방법
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