Preparation method of lithium iron phosphate-lithium vanadium phosphate flaky composite cathode material

A composite positive electrode material, lithium iron phosphate technology, applied in the direction of chemical instruments and methods, phosphorus compounds, battery electrodes, etc., can solve the problems of reduced electron mobility, poor low temperature performance and rate performance, low electronic conductivity, etc., to achieve excellent Electronic conductivity, ionic conductivity, and the effect of improving rate performance

Active Publication Date: 2017-02-22
CENT SOUTH UNIV
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Problems solved by technology

[0002] The conductivity of lithium iron phosphate is very poor, the capacity decays quickly when discharged at a high current, and the low-temperature performance and rate performance are poor; the metal ions in the crystal structure of lithium vanadium phosphate are far apart, which reduces the mobility of electrons in the material, resulting in The electronic conductivity is low, and the effect of charging and di

Method used

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  • Preparation method of lithium iron phosphate-lithium vanadium phosphate flaky composite cathode material
  • Preparation method of lithium iron phosphate-lithium vanadium phosphate flaky composite cathode material
  • Preparation method of lithium iron phosphate-lithium vanadium phosphate flaky composite cathode material

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Embodiment 1

[0024] Weigh 9.36g (0.08mol) of ammonium metavanadate, 3.19g (0.02mol) of ferric oxide, 18.40g (0.16mol) of ammonium dihydrogen phosphate, 5.91g (0.08mol) of lithium carbonate, and 7.20g (0.08mol) of oxalic acid mol), according to the molar ratio of vanadium atom, iron atom, phosphorus atom, lithium atom, carbon atom is 2:1:4:4:4 dissolved in 1L deionized water, and then according to the theoretical obtained lithium iron phosphate-lithium vanadium phosphate mass Add 0.678g of surfactant cetyltrimethylammonium bromide at 3%, control the concentration of vanadium ions in the solution to 0.08mol / L, adjust the pH value to 6 with ammonia water, stir with a magnetic stirrer for 11h, and obtain a uniform transparent solution ;Transfer the obtained homogeneous transparent solution to a high-pressure reactor, feed argon, react at a speed of 900rpm and a temperature of 250°C for 20h, wash, filter, dry, and grind to obtain lithium iron phosphate-vanadium phosphate Lithium composite mater...

Embodiment 2

[0028] Take 5.46g (0.03mol) of vanadium pentoxide, 4.32g (0.03mol) of ferrous oxalate, 12.47g (0.12mol) of lithium dihydrogen phosphate, and 3.36g (0.01075mol) of citric acid. Atoms, lithium atoms, and carbon atoms in a molar ratio of 2:1:4:4:3.5 were dissolved in 1L of deionized water, and then the surfactant polydioctyl succinate was added according to 1% of the theoretically obtained lithium iron phosphate-lithium vanadium phosphate mass. Sodium ester sulfonate 0.170g, control the vanadium ion concentration in the solution to be 0.06mol / L, adjust the pH value to 5 with ammonia water, stir with a magnetic stirrer for 10h, and obtain a homogeneous solution transparent solution; the obtained homogeneous transparent solution is transferred to a high pressure In the reaction kettle, a protective gas was introduced to react at a speed of 800 rpm and a temperature of 240°C for 25 hours. After washing, filtering, drying, and grinding, the precursor powder of lithium iron phosphate-l...

Embodiment 3

[0031] Weigh 16.55g (0.09mol) of sodium orthovanadate, 18.18g (0.045mol) of iron nitrate, 18.71g (0.18mol) of lithium dihydrogen phosphate, 5.78g (0.017mol) of sucrose , lithium atom, carbon atom molar ratio is 2:1:4:4:4.5 dissolved in deionized water, and then add surfactant octylphenyl polyvinyl ether according to 5% of the mass of lithium iron phosphate-lithium vanadium phosphate obtained theoretically 1.27g, control the concentration of vanadium ions in the solution to be 0.09mol / L, adjust the pH value to 7 with ammonia, stir with a magnetic stirrer for 12h, and obtain a homogeneous solution transparent solution; the obtained homogeneous transparent solution is transferred to an autoclave, Introduce protective gas, react at a speed of 1000rpm and a temperature of 260°C for 15 hours, wash, filter, dry, and grind to obtain a precursor powder of lithium iron phosphate-lithium vanadium phosphate composite material; Calcined at 780° C. for 15 hours in a non-oxidizing atmosphere...

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Abstract

The invention discloses a preparation method of a lithium iron phosphate-lithium vanadium phosphate flaky composite cathode material. The preparation method comprises the following steps that 1, a vanadium source, an iron source, a phosphorus source, a lithium source and an organic carbon source are dissolved into deionized water according to the molar ratio 2:1:4:4:(3-5) of vanadium atoms to iron atoms to phosphorus atoms to lithium atoms to carbon atoms, a surfactant is added, the pH value is regulated, and stirring is conducted; 2, the mixture is transferred into a high-pressure reaction kettle, protective gas is introduced, reacting is conducted for 10 h to 30 h at the speed of 200 rpm to 1,200 rpm at the temperature of 200 DEG C to 300 DEG C, and after washing, filtering and drying are conducted, grinding is conducted; 3, roasting is conducted in a non-oxidative atmosphere at the temperature of 600 DEG C to 800 DEG C, and then the material is obtained. The lithium iron phosphate-lithium vanadium phosphate flaky composite cathode material synthesized through the method has the excellent electronic conductivity and ionic conductivity and is excellent in electrochemical performance, good and stable in product homogeneity and low in cost.

Description

technical field [0001] The invention relates to a preparation method of lithium iron phosphate-lithium vanadium phosphate, a positive electrode material of a lithium ion battery, in particular to a preparation method of a sheet-shaped composite positive electrode material, lithium iron phosphate-lithium vanadium phosphate. Background technique [0002] The conductivity of lithium iron phosphate is very poor, the capacity decays quickly when discharged at a high current, and the low-temperature performance and rate performance are poor; the metal ions in the crystal structure of lithium vanadium phosphate are far apart, which reduces the mobility of electrons in the material, resulting in The electronic conductivity is low, and the effect of charging and discharging under high current is not ideal. Two traditional phosphate-based positive electrode materials are prepared together, and the high ion conductivity, high theoretical specific capacity and high discharge voltage of l...

Claims

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Application Information

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IPC IPC(8): H01M4/58H01M4/583H01M4/139H01M4/36H01M10/0525C01B25/45
CPCC01B25/45H01M4/139H01M4/362H01M4/366H01M4/5825H01M4/583H01M10/0525Y02E60/10
Inventor 童汇李晖张宝张杰喻万景张佳峰郑俊超
Owner CENT SOUTH UNIV
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