Lithium iron phosphate/PpyPy composite cathode material for boron-doped modification lithium ion battery and preparation method therefor

A composite positive electrode material and lithium-ion battery technology, applied in the direction of battery electrodes, circuits, electrical components, etc., can solve the problems of insignificant improvement of material electronic conductivity, reduction of material true density volume specific energy, reduction of material mass specific capacity, etc. , to achieve reversible electrochemical redox characteristics, high-temperature solid-phase synthesis process is simple, and the effect of improving electrochemical performance

Inactive Publication Date: 2012-07-11
SOUTH CHINA UNIV OF TECH
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Problems solved by technology

All the above methods and approaches can treat LiFePO to varying degrees. 4 The electrochemical properties of materials have been significantly improved, but each has defects that directly restrict its wide application:
[0004] 1. Although the liquid phase synthesis method can synthesize material powders with uniform particle size and fine particle size, which reduces the diffusion path of lithium ions, the improvement of the electronic conductivity of the material is not obvious, and the above method still has requirements for equipment High or complicated process, etc., it is difficult to carry out industrialized large-scale production;
[0005] 2. The method of simply coating carbon or metal powder can only effectively improve the electronic conductivity of the material, but the structure of pyrolytic carbon, the thickness of the carbon layer, the distribution of carbon on the surface and the concentration gradient of the metal powder will affect the coating effect. Moreover, the addition of too much carbon will significantly reduce the true density of the material and the volume specific energy of the material, and too much metal powder will reduce the mass specific capacity of the material;
[0006] 3. Doping metal (M) elements such as Ti or Co to form Li (M y Fe 1-y )PO4, which will reduce the stability of the crystal structure of the material, thereby affecting the electrical properties of the material

Method used

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  • Lithium iron phosphate/PpyPy composite cathode material for boron-doped modification lithium ion battery and preparation method therefor
  • Lithium iron phosphate/PpyPy composite cathode material for boron-doped modification lithium ion battery and preparation method therefor
  • Lithium iron phosphate/PpyPy composite cathode material for boron-doped modification lithium ion battery and preparation method therefor

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Experimental program
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Effect test

Embodiment 1

[0035] The first step is to weigh 10g of polyacrylonitrile powder and place it in a high-temperature furnace with automatic temperature control. Under the protection of argon atmosphere, conduct thermal cracking at 650°C at a heating rate of 3°C / min, and crush the resulting material Grind and sieve, and finally obtain black polypyridine conductive polymer material (PPyPy) with metallic luster;

[0036] In the second step, in order to prepare 0.1 mol lithium iron phosphate material, respectively weigh 0.05 mol lithium carbonate, 0.1 mol ferrous oxalate, 0.095 mol diammonium hydrogen phosphate and 0.05 mol boric acid, and then add 0.45 g PPyPy, using ethanol as a dispersant (its Adding amount is 1 / 2 of the total mass of raw materials), wet ball milling with planetary ball mill for 6 hours; mixing uniformly;

[0037] In the third step, the mixed raw materials are heated to 300°C at a heating rate of 2°C per minute in a nitrogen atmosphere, and heated at a constant temperature of 300°C...

Embodiment 2

[0041] The first step is to prepare 0.1mol lithium iron phosphate material, weigh out 0.0495mol lithium carbonate, 0.1mol ferrous oxalate, 0.095mol diammonium hydrogenphosphate / 0.05, 0.05mol boric acid, and then add 1.0g polyacrylonitrile powder. , Use ethanol as the dispersant (the added amount is 1 / 2 of the total mass of the raw materials), and mix evenly through high-speed ball milling;

[0042] In the second step, the mixed raw materials are heated to 350°C at a heating rate of 5°C per minute in a nitrogen atmosphere, heated at a constant temperature for 10 hours, cooled and ground to contain reaction precursors;

[0043] In the third step, the reaction precursor is heated to 650°C at a heating rate of 5°C per minute under the protection of a nitrogen atmosphere, and calcined at a constant temperature for 25 hours. After cooling, the boron-doped modified lithium ion battery lithium iron phosphate / polymer Pyridine composite cathode material (Li(FePO 4 ) 1-X (BO 3 ) x / PPyPy).

[...

Embodiment 3

[0046] The first step is to weigh out 10g of pre-oxidized polyacrylonitrile powder heated in an air atmosphere of 250°C for 2 hours, and place it in a high-temperature furnace with automatic temperature control. In an argon atmosphere, thermal cracking is carried out at 900°C. The heating rate is 10°C / min, crush and grind the obtained material through a sieve, and finally obtain a black polypyridine conductive polymer material (PPyPy) with metallic luster;

[0047] In the second step, in order to prepare 0.1mol lithium iron phosphate materials, weigh 0.05mol lithium hydroxide, 0.1mol ferrous oxalate, 0.0.092mol ammonium dihydrogen phosphate / 0.04mol diboron trioxide, and then add 0.15g PPyPy to ethanol It is a dispersant (the added amount is 1 / 2 of the total mass of the raw materials), wet ball milling with a planetary ball mill for 6 hours; mix evenly;

[0048] In the third step, the mixed raw materials are heated to 400°C at a heating rate of 15°C per minute in an argon atmosphere...

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Abstract

The invention discloses a lithium iron phosphate/PpyPy composite cathode material for a boron-doped modification lithium ion battery and the preparation method therefor. The method comprises the following steps: mixing materials such as lithium source compound, phosphorus source compound, ferric source compound, boron source compound, clad material conductive polymer PpyPy or conductive polymer thermal cracked presoma polyacrylonitrile, heating for 5 to 20 hours under the temperature of 250 to 400 DEG C, and a reaction precursor is obtained through cooling and ball milling; calcining the reaction precursor under 500 to 800 DEG C for 10 to 40 hours, and after cooling, composite cathode material for the boron-doped modification lithium ion battery can be obtained. In the invention, chemical composition, structures and particle size of the material of the modification lithium ion battery can be effectively controlled, the electronic conductivity and the lithium ion diffusion rate of the material are improved, and the electrochemical performance of the material is improved; and meanwhile, the synthesis process of the material is simplified, and the industrialized mass production can be performed conveniently.

Description

Technical field [0001] The invention relates to a positive electrode material for lithium ion batteries, in particular to a lithium iron phosphate / polypyridine composite positive electrode material for boron-doped modified lithium ion batteries and a preparation method thereof. Background technique [0002] Following lithium cobalt oxide (LiCoO 2 ), lithium nickelate (LiNiO 2 ), lithium manganate (LiMn 2 O 4 ) And lithium iron phosphate (LiFePO 4 ) Are used as cathode materials for lithium-ion batteries. Among them, LiCoO 2 The cost is high, the price is high, the resource is poor, and the toxicity is high; LiNiO 2 Difficult to prepare. Poor thermal stability and safety; LiMn 2 O 4 Although the safety performance is good, its capacity attenuation is obvious, and the cycle reversibility performance is poor; LiFePO with olivine crystal structure 4 It has the outstanding advantages of large discharge capacity, long cycle life, good safety performance, low price, non-toxic and no env...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/58
CPCY02E60/12Y02E60/10
Inventor 周震涛陈培华
Owner SOUTH CHINA UNIV OF TECH
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