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Lithium iron phosphate positive pole material

A cathode material, lithium iron phosphate technology, used in phosphorus compounds, battery electrodes, inorganic chemistry, etc., can solve the problem of low conductivity, and achieve the effect of good high current charge and discharge performance

Inactive Publication Date: 2009-04-01
SHENZHEN BAK BATTERY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

LiFePO 4 The main problem is that its conductivity is low, and the performance of high-current charging and discharging needs to be further improved.

Method used

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  • Lithium iron phosphate positive pole material
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  • Lithium iron phosphate positive pole material

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] The carbon source is acetylene black, and the lithium source is Li 2 CO 3 , the iron source is FeC 2 o 4 2H 2 O, magnesium source is Mg(OH) 2 , the phosphorus source is NH 4 h 2 PO 4 , molar ratio FeC 2 o 4 2H 2 O: NH 4 h 2 PO 4 : Li 2 CO 3 :Mg(OH) 2 =1:1:0.96:0.02, the amount of acetylene black added is FeC 2 o 4 2H 2 O, NH 4 h 2 PO 4 , Li 2 CO 3 and Mg(OH) 2 12wt% of the sum of the amount used, disperse the above-mentioned components in acetone evenly, put them into a ball mill to grind, heat to evaporate the acetone, put the mixed and ground materials into a nitrogen atmosphere tube furnace, heat at 300°C for 12h, cold cut After grinding, pressing into blocks, calcining at 650°C for 24h in a nitrogen atmosphere tube test furnace, cold cutting, and grinding to obtain the Li 0.96 Mg 0.02 FePO 4 / C cathode material.

[0019] With Li 0.96 Mg 0.02 FePO 4 / C is the positive electrode active material, conductive carbon black is the conductive ...

Embodiment 2

[0023] The difference between this embodiment and Embodiment 1 is that the carbon source is tar, and the lithium source is LiOH·H 2 O, iron source is FeO, magnesium source is MgO, phosphorus source is (NH4) 3 PO 4 , molar ratio FeO:(NH4) 3 PO 4 :LiOH·H 2 O:MgO=1:1:0.98:0.01, tar addition is FeO, (N H 4) 3 PO 4 , LiOH·H 2 8wt% of the sum of the amount of O and MgO. The cathode material of this embodiment is Li 0.98 Mg 0.01 FePO 4 / C.

[0024] The 18650 type experimental battery was manufactured according to the same recipe and process as in Example 1.

[0025] Carry out a cycle test of 5A charge / 15A discharge on the experimental battery, such as Figure 4 As shown, the capacity retention rate after 80 cycles is 97.81%. The initial discharge capacity of the sample battery reached 138.93mAh / g at room temperature.

Embodiment 3

[0027] The difference between this embodiment and embodiment one is: the carbon source is sucrose, and the iron source is Fe 2 o 3 , the magnesium source is Mg(H 2 PO 4 ) 2 2H 2 O, the phosphorus source is (NH 4 ) 2 HPO 4 , molar ratio Fe 2 o 3 :(NH 4 ) 2 HPO 4 : Li 2 CO 3 :Mg(H 2 PO 4 ) 2 2H 2 O=1:1:0.92:0.04, the amount of sucrose added is Fe 2 o 3 , (NH 4 ) 2 HPO 4 , Li 2 CO 3 and Mg(H 2 PO 4 ) 2 2H 2 15wt% of the sum of the amount of O used. The cathode material of this embodiment is Li 0.92 Mg 0.04 FePO 4 / C.

[0028] The 18650 type experimental battery was manufactured according to the same recipe and process as in Example 1.

[0029] Carry out a cycle test of 5A charge / 15A discharge on the experimental battery, such as Figure 4 As shown, the capacity retention rate after 80 cycles is 97.05%. The initial discharge capacity of the sample battery reached 139.46mAh / g at room temperature.

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Abstract

The invention provides a lithium iron phosphate positive electrode material, the chemical formula thereof is Li1-xMgx / 2FePO4 / C, wherein, x is not less than or equal to 0.01 and not more than or equal to 0.04. The positive electrode material Li1-xMgx / 2FePO4 / C still has an olivine structure of the lithium iron phosphate, the high-current cycle test of 5A under the charge / 15A under the discharge is carried out on a lithium-ion battery which adopts the positive electrode material Li1-xMgx / 2FePO4 / C at the normal temperature, the first discharge capacity is more than 138mAh / g, and the capacity retention rate after 80 cycles is more than 97 percent, thereby having good high-current charge-discharge performance.

Description

technical field [0001] The invention relates to a lithium iron phosphate positive electrode material, in particular to a lithium iron phosphate positive electrode material with good high-current charging and discharging performance. Background technique [0002] With its advantages of high energy density, high discharge voltage, large specific capacity and low self-discharge rate, lithium-ion secondary batteries have rapidly replaced traditional batteries in the fields of mobile phones, notebook computers, power tools and electric vehicles. The domestically researched positive electrode materials mainly include LiCoO 2 , LiNiO 2 and LiMn 2 o 4 , where the layered LiCoO 2 Due to its good electrode performance, it is widely used in the market as a cathode material for commercial lithium-ion batteries, but it has disadvantages such as high price and high pollution; spinel-structured LiMn 2 o 4 In recent years, it has been extensively and deeply studied, but its applicatio...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/58H01M4/48C01B25/45
CPCY02E60/10
Inventor 沈炎宾刘方
Owner SHENZHEN BAK BATTERY CO LTD
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