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Method of producing active compound lithium iron phosphate of lithium ion secondary battery anode

A positive active material and secondary battery technology, applied in battery electrodes, electrode manufacturing, chemical instruments and methods, etc., can solve the problems of poor conductivity and low specific capacity of lithium iron phosphate

Active Publication Date: 2008-04-02
BYD CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] The purpose of the present invention is to provide a method for preparing lithium iron phosphate, the positive electrode active material of lithium ion secondary batteries, in order to overcome the shortcomings of poor electrical conductivity and low specific capacity of lithium iron phosphate, the positive electrode active material of lithium ion secondary batteries prepared by the existing method, The cathode active material lithium iron phosphate (LiFePO) prepared by this method 4 ) good electrical conductivity and high specific capacity

Method used

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  • Method of producing active compound lithium iron phosphate of lithium ion secondary battery anode
  • Method of producing active compound lithium iron phosphate of lithium ion secondary battery anode
  • Method of producing active compound lithium iron phosphate of lithium ion secondary battery anode

Examples

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preparation example Construction

[0015] The invention provides a method for preparing lithium iron phosphate, a positive electrode active material of a lithium ion secondary battery, wherein the method comprises:

[0016] (1) The conductive agent particles, the aqueous solution containing iron ions and / or ferrous ions and the aqueous solution containing phosphate ions are mixed, the solid product is separated and washed to obtain ferric phosphate and / or ferrous phosphate precipitation containing conductive agent particles ;

[0017] (2) The ferric phosphate and / or ferrous phosphate precipitate containing conductive agent particles obtained in (1) is mixed with a lithium source, and calcined in an inert or reducing atmosphere.

[0018] The conductive agent can increase the conductivity of the electrode and reduce the contact resistance between the positive active material lithium iron phosphate and the current collector. In the prior art, in the process of preparing the positive electrode of the battery, the p...

Embodiment 1

[0036] This example illustrates the preparation method of lithium iron phosphate, the positive electrode active material of lithium ion secondary battery, provided by the present invention.

[0037] 8 mol / liter of ferric nitrate solution and 8 mol / liter of phosphoric acid solution are fed through J-W-22 / 0.2 metering pump (Huai'an Huayu Metering Pump Co., Ltd.) at a speed of 50 ml / min to contain 3 grams Diameter is in the 1 liter capacity reactor of the carbon black particle of 5 microns, two kinds of solutions respectively add 250 milliliters, start to stir with the rotating speed of 400 revs / min while inputting liquid, stir 30 minutes altogether; The metering pump feeds 30 wt% H at a rate of 0.1 L / min 2 o 2 The total solution is 0.5 liters. The resulting precipitate was centrifuged at 2000 rpm, then washed with deionized water until the ion concentration in the washing solution was 0.0008 mol / L, and dried at 120° C. for 0.5 hour to obtain iron phosphate with a conductive ag...

Embodiment 2

[0040] This example illustrates the preparation method of lithium iron phosphate, the positive electrode active material of lithium ion secondary battery, provided by the present invention.

[0041] Stir and mix 1 liter of 5 mol / liter ammonium hydrogen phosphate solution and 40 grams of acetylene black particles with a diameter of 5 microns in a 3-liter volume reactor to form a uniform suspension, and feed it to the reactor at a speed of 0.1 liter / minute through a metering pump. Into the kettle, 1 liter of ferrous oxalate solution of 5 mol / liter was input. While inputting the ferrous oxalate solution, it began to stir at a speed of 600 rpm, and stirred for 30 minutes at this speed; Pump 0.2 L / min to add 30 wt% H 2 o 2 The total solution is 1 liter. The resulting precipitate was centrifuged at 2500 rpm, washed with deionized water until the ion concentration in the washing solution was 0.0005 mol / L, and dried at 180° C. for 0.3 hour to obtain iron phosphate with a conductive ...

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Abstract

The present invention provides a method preparing phosphate iron lithium, which is lithium ion secondary battery anode active material. Steps of the method are as follows: conductive agent particle, an aqueous solution comprising iron ion and / or ferrous ion and the aqueous solution comprising phosphate ion are mixed; a solid product is separated and washed; the solid product and lithium source are mixed and roasted in reducing or inert atmosphere. The anode active material of phosphate iron lithium crystal prepared by the method is good in structure and high in specific capacity.

Description

technical field [0001] The present invention relates to a preparation method of a positive electrode active material of a lithium ion secondary battery, in particular to a lithium iron phosphate (LiFePO 4 ) preparation method. Background technique [0002] Since lithium ions are in lithium iron phosphate (LiFePO 4 ) in the electrochemical deintercalation process is reversible, and lithium iron phosphate (LiFePO 4 ) The theoretical discharge specific capacity of the polycrystal can reach 170 mAh / g, so the olivine-type positive electrode active material LiMPO with an ordered structure 4 It is considered to be a positive electrode active material for lithium-ion secondary batteries with great application potential. [0003] In the prior art, the positive electrode active material LiFePO is generally prepared by solid phase method or wet chemical method. 4 , such as CN 1401559A discloses a lithium iron phosphate (LiFePO 4 ) preparation method, in which lithium salt, ferrous...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/45H01M4/04H01M4/58H01M4/48
CPCY02E60/12Y02E60/10
Inventor 刘飞
Owner BYD CO LTD