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Electrochemical device and electronic device

An electrochemical and conductive agent technology, which is applied in the field of electrochemical energy storage, can solve the problems of uneven ratio of negative electrode capacity to positive electrode capacity, uneven local density of electrode pieces, and reduced cycle performance of electrochemical devices, etc., to achieve slow decomposition of lithium. Effect

Active Publication Date: 2021-07-09
NINGDE AMPEREX TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0002] During the charging and discharging process of electrochemical devices (for example, lithium-ion batteries), lithium ions will be continuously deintercalated and intercalated on the positive and negative electrodes, but due to the uneven local density of the pole piece or the corresponding capacity of the negative electrode and the positive electrode The problem of local inhomogeneity in the ratio of capacity leads to the problem of inhomogeneous distribution of lithium ion transport kinetics in electrochemical devices during cycling
The region with insufficient kinetics of the negative electrode will lead to lithium precipitation, which will seriously reduce the cycle performance of the electrochemical device

Method used

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  • Electrochemical device and electronic device

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Embodiment 1

[0047] Preparation of the positive pole piece: Aluminum foil is used as the positive current collector of the positive electrode, and the positive active material lithium cobaltate, the conductive agent conductive carbon black, and polyvinylidene fluoride are dissolved in N-methylpyrrolidone at a weight ratio of 97.8:1.4:0.8 (NMP) solution to form a slurry of a positive electrode active material layer, and coat the slurry on a positive electrode current collector with a coating thickness of 80 μm to obtain a positive electrode active material layer. After drying, cold pressing and cutting, the positive electrode sheet is obtained.

[0048] Preparation of negative electrode sheet: Graphite M, sodium carboxymethyl cellulose (CMC) and binder styrene-butadiene rubber were dissolved in deionized water at a weight ratio of 97.7:1.3:1 to form the first slurry. Adopt 10 μm thick copper foil as the current collector of the negative electrode sheet, apply part of the first slurry on the...

Embodiment 2

[0056] Preparation of the positive pole piece: Aluminum foil is used as the positive current collector of the positive electrode, and the positive active material lithium cobaltate C, the conductive agent conductive carbon black, and polyvinylidene fluoride are dissolved in N-methyl A first slurry was formed in a pyrrolidone (NMP) solution, and part of the first slurry was coated on the positive electrode current collector to a thickness of 40 μm to obtain a first active material layer. The positive active material lithium cobaltate D, conductive carbon black, and polyvinylidene fluoride are dissolved in N-methylpyrrolidone (NMP) solution at a weight ratio of 97.8:1.4:0.8 to form a second slurry. The first slurry and the second slurry were coated on the first active material layer by using interval coating technology, and the coating thickness was 40 μm to obtain a second active material layer. After drying, cold pressing and cutting, the positive electrode sheet is obtained. ...

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Abstract

The invention provides an electrochemical device and an electronic device. The electrochemical device includes a pole piece including a current collector, a first active material layer, and a second active material layer. The first active material layer includes a first active material. The first active material layer is located between the current collector and the second active material layer. The second active material layer comprises at least one first part and at least one second part which are arranged along the length direction of the current collector, wherein the first part comprises a second active material, and the second part comprises a third active material. The difference between the lithium ion diffusion rate of the combination of the first and third parts and the lithium ion diffusion rate of the combination of the second and fourth parts is greater than 5%. The electrochemical device can relieve the problem of lithium precipitation caused by non-uniform dynamics.

Description

technical field [0001] The present application relates to the field of electrochemical energy storage, in particular to electrochemical devices and electronic devices. Background technique [0002] During the charging and discharging process of electrochemical devices (for example, lithium-ion batteries), lithium ions will be continuously deintercalated and intercalated on the positive and negative electrodes, but due to the uneven local density of the pole piece or the corresponding capacity of the negative electrode and the positive electrode The problem of local inhomogeneity in the ratio of capacity leads to the problem of inhomogeneous distribution of lithium ion transport kinetics in electrochemical devices during cycling. The area with insufficient kinetics of the negative electrode will lead to lithium precipitation, which will seriously reduce the cycle performance of the electrochemical device. Contents of the invention [0003] An embodiment of the present appl...

Claims

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Application Information

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IPC IPC(8): H01M4/13H01M10/0525H01M10/0587
CPCH01M4/13H01M10/0525H01M10/0587Y02P70/50Y02E60/10
Inventor 付奥龚美丽
Owner NINGDE AMPEREX TECH