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Application of a bismuth-doped lithium vanadium phosphate cathode material in lithium-ion batteries

A lithium ion battery, lithium vanadium phosphate technology, applied in the direction of phosphate, phosphorus oxyacid, battery electrode, etc., can solve the problems of poor high-voltage cycle stability, poor high-current discharge performance, difficult diffusion, etc., and achieves a modification method. Simple, effective and easy to operate

Active Publication Date: 2018-11-27
DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, lithium vanadium phosphate has the following disadvantages that hinder its practical application: (1) V in the synthesis 3+ easily oxidized to V 5+ It is not easy to obtain single-phase Li 3 V 2 (PO 4 ) 3 ; (2) lithium ion in Li 3 V 2 (PO 4 ) 3 Difficulty in diffusion leads to low utilization of active materials; (3) Li 3 V 2 (PO 4 ) 3 Its own electronic conductivity is very low, resulting in poor high-current discharge performance; (4) Poor high-voltage cycle stability

Method used

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  • Application of a bismuth-doped lithium vanadium phosphate cathode material in lithium-ion batteries
  • Application of a bismuth-doped lithium vanadium phosphate cathode material in lithium-ion batteries
  • Application of a bismuth-doped lithium vanadium phosphate cathode material in lithium-ion batteries

Examples

Experimental program
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Embodiment 1

[0022] Dissolve 0.002985 mol of oxalic acid in a beaker filled with deionized water, then add 0.00995 mol of vanadium pentoxide, stir in a constant temperature water bath at 70-80°C until it turns into a blue solution, then add 0.003 mol of ammonium dihydrogen phosphate , 0.0001mol of bismuth nitrate, 0.0015mol of lithium carbonate, continue to stir to form blue-green doped lithium vanadium phosphate sol (Li:V:Bi:PO 4 3- =3:1.99:0.01:3). The sol was baked in an oven at 80°C for about 10 hours to obtain a blue fluffy precursor, which was ground into powder and placed in a tube furnace, and heated at a rate of 3°C / min to 350°C and keep it warm for 4 hours, take it out after cooling down and grind it, continue to raise the temperature to 750°C at a rate of 3°C / min and keep it warm for 10 hours, after ICP quantitative analysis, the composition is Li 3 V 1.99 Bi 0.01 (PO 4 ) 3 composite powder.

Embodiment 2

[0024] Dissolve 0.002955mol of oxalic acid in a beaker filled with deionized water, then add 0.00985mol of vanadium pentoxide, stir in a constant temperature water bath at 70-80°C until it turns into a blue solution, then add 0.003mol of ammonium dihydrogen phosphate , 0.0003mol of bismuth nitrate, 0.0015mol of lithium carbonate, and continue to stir to form blue-green doped lithium vanadium phosphate sol (Li:V:Bi:PO 4 3- =3:1.97:0.03:3). Place the sol in an oven at 80°C and bake for about 10 hours to obtain a blue fluffy precursor. Grind the precursor into powder and place it in a tube furnace. Under an argon atmosphere, heat up at a rate of 3°C / min. to 350°C and keep it warm for 4 hours, after cooling down, take it out for grinding, continue to heat up to 750°C at a heating rate of 3°C / min and keep it warm for 10 hours, after ICP quantitative analysis, the composition is Li 3 V 1.97 Bi 0.03 (PO 4 ) 3 composite powder.

Embodiment 3

[0026] Dissolve 0.002925 mol of oxalic acid in a beaker filled with deionized water, then add 0.00975 mol of vanadium pentoxide, stir in a constant temperature water bath at 70-80°C until it turns into a blue solution, then add 0.003 mol of ammonium dihydrogen phosphate , 0.0005mol of bismuth nitrate, 0.0015mol of lithium carbonate, and continue to stir to form blue-green doped lithium vanadium phosphate sol (Li:V:Bi:PO 4 3- =3:1.95:0.05:3). Place the sol in an oven at 80°C and bake for about 10 hours to obtain a blue fluffy precursor. Grind the precursor into powder and place it in a tube furnace. Under an argon atmosphere, heat up at a rate of 3°C / min. to 350°C and keep it warm for 4 hours, after cooling down, take it out for grinding, continue to heat up to 750°C at a heating rate of 3°C / min and keep it warm for 10 hours, after ICP quantitative analysis, the composition is Li 3 V 1.95 Bi 0.05 (PO 4 ) 3 composite powder.

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Abstract

The invention relates to the application of a bismuth-doped lithium vanadium phosphate cathode material in a lithium ion battery. The composition of the cathode material is Li3V2-xBix(PO4)3, 0.01<x<0.15. Compared with the positive electrode material of lithium vanadium phosphate doped with bismuth of the present invention, electronic conductivity and ion conductivity are greatly improved; as lithium ion positive electrode material, the initial discharge specific capacity, cycle performance And rate performance has also been greatly improved.

Description

technical field [0001] The invention relates to the application of a bismuth-doped lithium vanadium phosphate cathode material in lithium ion batteries, belonging to the fields of chemical power source materials and lithium ion batteries. Background technique [0002] Lithium-ion batteries have the advantages of high specific energy, small self-discharge coefficient, long cycle life, light weight and environmental friendliness, and become a strong competitor for electric vehicles and hybrid vehicles. Common power lithium-ion cathode materials include spinel lithium manganese oxide, lithium cobalt oxide and polyanion cathode materials (LiMPO 4 , M=Mn, Fe, V, etc.). Among them, polyanionic lithium iron phosphate (LiFePO 4 ) has long cycle life, high safety, and low price, but has defects such as poor electronic ion conductivity, low diffusion coefficient of lithium ions, and poor high-current discharge characteristics. Lithium vanadium phosphate (Li 3 V 2 (PO 4 ) 3 ) th...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/58H01M4/36H01M4/62H01M10/0525C01B25/45C01B25/26
CPCH01M4/362H01M4/5825H01M4/62H01M10/0525Y02E60/10
Inventor 张华民程意冯凯李先锋
Owner DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI