Preparation method of lithium ion battery positive electrode material

A technology for lithium ion batteries and positive electrode materials is applied in the field of preparation of positive electrode materials for lithium ion secondary batteries, and can solve the problems affecting material processing performance and compaction density, potential safety hazards in transportation and storage, and easily exceeding the standard of magnetic impurities in synthetic products. , to achieve the effect of excellent water absorption and high temperature cycle performance, good consistency and short sintering time

Inactive Publication Date: 2018-05-04
PULEAD TECH IND
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Problems solved by technology

The disadvantages of the above technologies are: First, the sintering process involves complex physical and chemical changes, such as carbon source pyrolysis, carbothermal reduction, lithium carbonate decomposition, etc., so a slight change in the sintering conditions during the first sintering will lead to the synthesis path. Changes, which in turn affect the physical indicators and electrical properties of the product, resulting in poor consistency of the material prepared by one-time sintering; on the other hand, the sintering process Li 2 CO 3 Decomposition produces large amounts of CO 2 , A large amount of gas is discharged in a short period of time, resulting in an increase in the pores of the product particles, which affects the processing performance and compaction density of the material
The disadvantages of this technology are: 1. The introduction of strong reducing and magnetic metal iron powder in the secondary sintering process has potential safety hazards in transportation and storage, and the magnetic impurities of the synthesized products are easy to exceed the standard; 2. Lithium iron phosphate is not carbonized during the synthesis process. Coating, poor electrical performance
[0014] In addition, the research found (document Feng Yu, Jingjie Zhang, Reaction mechanism and electrochemical performance of LiFePO 4 / C cathode materials synthesized by carbothermal method[J].Electrochimica Acta.2009), in Li 2 CO 3 , Fe(NO 3 ) 3 9H 2 O, NH 4 h 2 PO 4 Synthesis of LiFePO as raw material 4 In the process, the intermediate product Li will be formed 3 Fe 2 (PO 4 ) 3 , the existence of this competitive reaction makes it difficult to control the reaction process when synthesizing lithium iron phosphate materials, the synthesis time is longer (>10h), the batch stability is poor, and the product has impurities, which reduces the electrochemical performance of the material
[0015] In addition, the ferric phosphate or ferrous phosphate raw materials used in the above patents usually contain crystal water. Before using it as a raw material to synthesize lithium iron phosphate, it is necessary to sinter in an air atmosphere to remove water. This is an essential step. The above patents No pre-calcination treatment is used, which is one of the reasons for the poor performance of the prepared positive electrode material

Method used

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  • Preparation method of lithium ion battery positive electrode material
  • Preparation method of lithium ion battery positive electrode material
  • Preparation method of lithium ion battery positive electrode material

Examples

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Embodiment 1

[0037] This embodiment provides a method for preparing a lithium-ion battery positive electrode material, the steps are as follows:

[0038] Will Li 2 CO 3 、FePO 4 2H 2 O was mixed in a molar ratio of 1:2. The mixed raw materials were put into a muffle furnace and pre-fired at 500°C for 5 hours to obtain a red powder, which was Li 3 Fe 2 (PO 4 ) 3 and Fe 2 o 3 mixture, its XRD such as figure 1 shown. After the temperature of the mixture dropped to room temperature, it was put into deionized water for grinding, the grinding rate was 1000r / min, and FePO was added in 0.5h 4 2H 2 O quality 10% glucose, continue to grind at the same rate for 0.5h, then continue to grind at a high rate (3000r / min) for 0.5h. After drying, in a nitrogen atmosphere, the second sintering was carried out at 600 ° C for 6 hours to obtain LFP / C, the morphology of which is as follows figure 2 .

[0039] Using N-methylpyrrolidone as a solvent, stir the powder obtained after sintering with con...

Embodiment 2

[0041] This embodiment provides a method for preparing a lithium-ion battery positive electrode material, the steps are as follows:

[0042] LiOH, Li 2 CO 3 、FePO 4 Mixing was performed at a molar ratio of 0.5:0.25:1. The mixed raw materials were put into a muffle furnace for pre-calcination at 700°C for 4.5h to obtain Li 3 Fe 2 (PO 4 ) 3 and Fe 2 o 3 mixture. After the temperature of the mixture dropped to room temperature, it was put into a mixed solution of deionized water and ethanol at a volume ratio of 1:1 for grinding, the grinding rate was 1000r / min, and FePO 4 Glucose with a mass of 9% was ground at the same rate for 0.5h, and then at a high rate (3000r / min) for 0.5h. After drying, the second sintering was carried out at 700° C. for 6 h in a nitrogen atmosphere to obtain LFP / C.

[0043] Refer to Example 1 for the battery preparation process.

Embodiment 3

[0045] This embodiment provides a method for preparing a lithium-ion battery positive electrode material, the steps are as follows:

[0046] Will Li 2 CO 3 , Fe 4 (P 2 o 7 ) 3 and Fe 2 o 3 Mixing was carried out in a molar ratio of 3:1:1. The mixed raw materials were put into a muffle furnace and pre-fired at 500 °C for 5 hours to obtain Li 3 Fe 2 (PO 4 ) 3 and Fe 2 o 3 mixture. After the temperature of the mixture dropped to room temperature, it was put into methanol and ground at a grinding rate of 1000r / min, and Fe was added after 0.5h. 4 (P 2 o 7 ) 3 10% polyethylene glycol by mass and 5% glucose were ground at the same rate for 0.5 h, and then at a high rate (3000 r / min) for 0.5 h. After drying, the LFP / C was obtained by secondary sintering at 600° C. for 6 h in an argon atmosphere.

[0047] Reference Example 1 for the manufacture of electrode sheet and battery.

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Abstract

The invention provides a preparation method of a lithium ion battery positive electrode material. The preparation method comprises the steps of mixing a lithium source, an iron source and a phosphatesource according to a mole ratio of Li, Fe and P being (1-1.02):(0.955-1):1, and performing pre-sintering in air to obtain a mixture of Li3Fe2(PO4)3 and Fe2O3, wherein the sintering time is 4-5 hours,and the sintering temperature is 500-700 DEG C; and mixing the mixture and a carbon source of which the mass accounts for 3-10% of Li3Fe2(PO4)3, grinding in a grinding medium, and performing secondary sintering under a non-oxidization or reduction atmosphere after drying to obtain an LFP / C positive electrode material, wherein the sintering time is 5-6 hours, and the sintering temperature is 600-800 DEG C. By the method, the smoothness of synthesis particle and the batch stability and the cycle stability of a product can be effectively improved.

Description

technical field [0001] The invention belongs to the technical field of batteries, and in particular relates to a preparation method of a positive electrode material of a lithium ion secondary battery. Background technique [0002] Lithium-ion batteries firmly occupy the consumer electronics market due to their advantages such as high energy density, low self-discharge, safety and environmental protection. In recent years, with the rise of electric vehicles and energy storage fields, a single lithium cobalt oxide (LiCoO 2 ) batteries have been difficult to meet market demand. Lithium iron phosphate (LiFePO 4 ) cathode material has become a research hotspot in recent years and has been successfully applied in electric vehicles due to its advantages of abundant main element reserves, low price, and high safety. [0003] LiFePO 4 The synthesis of (LFP) usually requires mixing, grinding, and sintering of phosphorus sources, iron sources, and lithium sources in a certain ratio...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/525H01M4/58H01M4/62H01M10/0525B82Y30/00
CPCB82Y30/00H01M4/366H01M4/525H01M4/5825H01M4/625H01M10/0525Y02E60/10
Inventor 田娜黄勇平张淑萍成富圈杨新河周恒辉
Owner PULEAD TECH IND
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