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Method for improving long cycle performance of thick electrode of layered positive electrode material under high voltage

A positive electrode material and high-voltage technology, applied in battery electrodes, circuits, electrical components, etc., can solve problems such as poor high-voltage performance of thick electrodes, and achieve the effects of accelerating lithium ion transmission, improving power performance, and avoiding cracking

Pending Publication Date: 2022-04-15
HUAZHONG UNIV OF SCI & TECH
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Problems solved by technology

[0005] Aiming at the defects of the prior art, the present invention provides a method for improving the long-term cycle performance of a layered positive electrode material thick electrode under high voltage. The thick electrode structure containing the layered positive electrode material is designed to ensure that the active particles in the thick electrode have Unobstructed ion and electron conduction, thereby increasing the uniformity of the reaction of the cathode material in the thick electrode, improving the long-term cycle stability, and solving the problem of improving the long-cycle performance of the layered cathode material electrode at the material level by improving the long-term cycle performance at the material level. Improve the electrochemical performance of thin electrodes, but the high voltage performance of thick electrodes is still not good, etc.

Method used

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  • Method for improving long cycle performance of thick electrode of layered positive electrode material under high voltage
  • Method for improving long cycle performance of thick electrode of layered positive electrode material under high voltage

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preparation example Construction

[0035] The present invention is used for the preparation of a thick electrode of a layered positive electrode material, and the electrode active material in step (1) is selected from lithium cobaltate or a ternary positive electrode material, and the ternary positive electrode material is LiNi x co y mn 1-x-y o 2 , where 0≤x≤1, 0≤y≤1. For example, the ternary cathode material LiNi 5 co 3 mn 2 o 2 ,LiNi 6 co 2 mn 2 o 2 ,LiNi 7 co 1 mn 2 o 2 , LiNi 8 co 1 mn 1 o 2 Wait. The increase of nickel content in layered cathode materials is accompanied by the increase of specific capacity.

[0036] In some embodiments, the water-based binder in step (1) is selected from one of sodium alginate, guar gum, polyacrylic acid, polyacrylonitrile, polyacrylate, styrene-butadiene rubber emulsion and carboxymethyl cellulose Or a mixture of several types. In a preferred embodiment, the binding agent is a mixture of guar gum, carboxymethyl cellulose or polyacrylic acid, and these...

Embodiment 1

[0051] single crystal LiNi 7 co 1 mn 2 o 2 , Binder carboxymethyl cellulose, conductive agent KB800 and carbon fiber are dispersed in deionized water according to the mass ratio of 0.9:0.05:0.035:0.015 and mixed evenly in a Zhongyi disperser to obtain a mixed slurry. The solid content of the slurry is is 45wt.%. The prepared pole piece was coated with a loading capacity of 20 mg cm -2 . Put the wet pole piece in a low-temperature environment of -60°C and freeze it for 3 hours, then dry the pole piece at -10°C and a low pressure of 5 Pa for 12 hours, and then obtain a thick electrode with low tortuosity. And the pole piece was used for the characterization of electrochemical performance after rolling.

[0052] 2. Preparation of SEM samples

[0053] The pole pieces before and after rolling were prepared into SEM samples, and the morphology of the surface and cross section were observed respectively.

[0054] 3. Assemble the battery and test the electrochemical performanc...

Embodiment 2

[0059] The positive electrode material is polycrystalline LiNi 7 co 1 mn 2 o 2 , other conditions are with embodiment 1.

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Abstract

The invention belongs to the technical field of lithium batteries, and particularly relates to a method for improving the long cycle performance of a layered positive electrode material thick electrode under high voltage. The method comprises the steps that after slurry mixing and coating are conducted, a solvent in slurry is dried, through the liquid phase-solid phase-gas phase conversion process of the solvent, the uniformity of liquid-phase slurry and the orderliness of solid-phase slurry are kept for final dried electrode components, and the low-tortuosity thick electrode with directionally-arranged pore channels is formed. On one hand, the conductive agent and the binder in the low-tortuosity electrode are uniformly distributed, and on the other hand, the construction of the lithium ion transmission pore channel is beneficial to full infiltration of an electrolyte on a pole piece and rapid transmission of lithium ions, so that a sufficient electron and lithium ion transmission network around each particle in the electrode can be effectively ensured; the uniformity of electrochemical reaction in the thick electrode is ensured, and the cracking of particles caused by the volume change of each special shape is effectively avoided, so that the long-cycle stability is improved.

Description

technical field [0001] The invention belongs to the technical field of lithium batteries, and more specifically relates to a method for improving the long-term cycle performance of a layered positive electrode material thick electrode under high voltage, in particular to a method for improving the layered positive electrode material thick electrode under high voltage through electrode structure design. method for long cycle performance. Background technique [0002] Lithium-ion batteries have the advantages of high specific energy, long cycle life, high working voltage, small self-discharge and no memory effect, and have been widely used in electric vehicles and energy storage systems and other fields. Power batteries and 3C products put forward higher requirements for battery life and fast charging capabilities, so it is necessary to build a battery system with high energy density and high power density. [0003] In lithium-ion batteries, the cathode material is the most c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/139
Inventor 谢佳李书萍何仁杰张策韩智龙
Owner HUAZHONG UNIV OF SCI & TECH
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