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Positive electrode piece having concentration gradient and preparation method thereof

A positive pole piece and concentration gradient technology, which is applied in the field of positive pole piece with concentration gradient and its preparation, can solve the problem of unsolved performance deterioration, unimproved contact between current collector and active material, large internal resistance, reduction of positive electrode material gram capacity, etc. problems, to achieve the effect of providing thermal stability and cycle performance, improving cell gas production, and reducing charge transfer resistance

Pending Publication Date: 2019-09-06
SUNWODA ELECTRIC VEHICLE BATTERY CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The coating material introduced by this method will reduce the gram capacity of the positive electrode material, and does not improve the problem of large contact internal resistance between the current collector and the active material; for example, Chinese patent CN106602076A discloses a preparation method and application of carbon-coated aluminum foil. The carbon-coated aluminum foil is made of The SUPER P conductive layer, graphene conductive layer and mixed conductive layer arranged in turn on at least one surface of the aluminum foil and the lead-aluminum foil can prepare a high-power power battery, but this method does not solve the problem of side reactions between the ternary material and the electrolyte. Issues that lead to poor performance

Method used

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  • Positive electrode piece having concentration gradient and preparation method thereof
  • Positive electrode piece having concentration gradient and preparation method thereof

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Effect test

Embodiment 1

[0028] In order to make the technical solutions and beneficial effects of the present invention easier to understand, the following will be described in detail in conjunction with the accompanying drawings and specific embodiments, as figure 1 Shown is the preparation flow chart, figure 2 is a schematic diagram of a positive electrode sheet with a concentration gradient,

[0029] 1. Take 4kg of active material (NCM811), 1kg of conductive carbon black, 1kg of binder (PVDF) and fully stir and disperse in a mixing tank to prepare slurry 1. Take 14kg of active material (NCM811), 1kg of conductive carbon black, viscous Binder (PVDF) 1kg was fully stirred and dispersed in another stirring tank to prepare slurry 2,

[0030] 2. In an environment with a relative humidity of 1%, transfer slurry 1 and slurry 2 to storage tanks and stir for 60 minutes at a speed of 350rmp;

[0031] 3. Coat the slurry 1 on the aluminum foil, control the coating thickness to account for 10% of the total ...

Embodiment 2

[0036] 1. Take 6kg of active material (NCM811), 1kg of conductive carbon black, 1kg of binder (PVDF) and fully stir and disperse in a mixing tank to prepare slurry 1. Take 12kg of active material (NCM811), 1kg of conductive carbon black, viscous Binder (PVDF) 1kg was fully stirred and dispersed in another stirring tank to prepare slurry 2,

[0037] 2. According to the same method as in Example 1, a positive electrode sheet with a concentration gradient is prepared,

[0038] After rolling, slitting, and die-cutting, the prepared positive electrode sheet was assembled into a pouch battery. The negative electrode was made of graphite, and the electrolyte was an EC / PC / DEC system containing LiPF6 (1mol / L). Table 1 shows the test structure of the capacity retention rate and cycle DCR growth (voltage range 2.8~4.3V) of 1C charge-discharge cycle at room temperature for 1000 cycles, and the discharge performance at 2C and 3C.

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Abstract

The invention discloses a positive electrode piece having concentration gradient and a preparation method thereof. The method is characterized by preparing active substances, conductive agents and binding agents in different proportions into slurry 1 and slurry 2, and then, coating the slurry 1, the slurry 2 and the slurry 1 on an aluminum foil through a step coating method to prepare the positiveelectrode piece having the concentration gradient. The active substances on the positive electrode piece are mostly concentrated on an intermediate layer, so that microcracks caused due to size expansion and contraction of a battery in the charging and discharging process can be reduced; the side close to a current collector and the side away from the current collector are rich in the conductiveagents and the binding agents, thereby facilitating fast charge transfer, reducing charge transfer impedance and effectively improving rate capability and power performance of a battery core; and direct contact between the electrolyte and a positive electrode material can be avoided to some extent, thereby relieving the problem of gas production of the battery core, and improving thermal stabilityand cycling performance of the battery.

Description

technical field [0001] The invention relates to the field of new energy power batteries and in particular to a positive electrode sheet with a concentration gradient and a preparation method thereof. Background technique [0002] Lithium-ion batteries have the advantages of high energy density, low self-discharge rate, small size, light weight, and long cycle life, and are widely used in portable electronic devices and new energy electric vehicle batteries. In lithium battery systems, ternary materials rely on high The advantages of energy density, low cost, and high platform voltage have become the focus of attention of positive electrode materials. However, ternary materials have the disadvantage of poor electrical conductivity, which leads to high charge transfer resistance, and the binder particles of the electrode sheet are uneven during the vacuum drying process. Generally, there is less binder on the side close to the current collector, and the contact internal resist...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/131H01M4/1391H01M4/04H01M4/62
CPCH01M4/0404H01M4/625H01M4/623H01M4/131H01M4/1391Y02E60/10
Inventor 刘甜甜鲁俊文李强杨从强段继祥张家宝吕磊张耀
Owner SUNWODA ELECTRIC VEHICLE BATTERY CO LTD
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