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Negative electrode for lithium battery and preparation method thereof and lithium battery

A lithium battery and negative electrode technology, applied in the field of lithium battery electrodes, can solve problems such as poor cycle stability, limit the energy density of lithium ion batteries, affect battery capacity, etc., and achieve the goal of ensuring stability, maintaining integrity and stability, and maintaining performance Effect

Active Publication Date: 2018-10-19
桑德新能源技术开发有限公司 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Graphite is currently the most important negative electrode material in the market, but its specific capacity is low (only 372mAh / g), and its electrochemical performance is poor at high battery density, which limits the further improvement of the energy density of lithium-ion batteries.
[0003] The silicon-based negative electrode has the highest theoretical specific capacity, as high as 4200mAh / g, but it also has many problems: the silicon particles on the electrode are accompanied by volume expansion and shrinkage when deintercalating lithium. A series of problems such as poor conductivity and SEI film rupture lead to a rapid decline in battery capacity
This traditional method will bring many problems: due to the large volume change of silicon in the process of charging and discharging, it is easy to cause a significant difference in the expansion degree of silicon particles and graphite particles in the mixed electrode during the lithium intercalation process, which in turn leads to electrode rupture. , pulverization, and finally inactivation of active substances, resulting in poor cycle stability
At the same time, the traditional silicon-carbon hybrid electrode will form an SEI film to cover the surface of the silicon material when it is charged and discharged for the first time. The volume effect of the silicon material will cause repeated destruction and reconstruction of the SEI film, thereby increasing the consumption of lithium ions and ultimately affecting battery capacity

Method used

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  • Negative electrode for lithium battery and preparation method thereof and lithium battery
  • Negative electrode for lithium battery and preparation method thereof and lithium battery
  • Negative electrode for lithium battery and preparation method thereof and lithium battery

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0068] A circular hole mask plate with a thickness of 40 μm, a through hole diameter of 10 μm, and a distance between circle centers of 30 μm was tightly attached to the copper current collector.

[0069] Weigh silicon powder (average particle size 100nm), PVDF and acetylene black and disperse them in N-methylpyrrolidone to make silicon slurry. The weight ratio of each component in the material is 90:5:5.

[0070] Apply the silicon slurry on the copper current collector with the mask plate; then gently remove the mask plate, leaving a cylindrical silicon molding unit on the copper current collector; then place it in a vacuum oven, Take it out after baking at 120°C for 2 hours to obtain a copper current collector / cylindrical silicon electrode.

[0071] Weigh graphene, PTFE and acetylene black and disperse them in N-methylpyrrolidone to make graphene slurry. The weight ratio of each component in the material is 80:10:10. Then apply graphene slurry on the exposed current collect...

Embodiment 2

[0074] A circular hole mask with a thickness of 100 μm, a through hole diameter of 50 μm, and a distance between circle centers of 70 μm was tightly attached to the copper current collector.

[0075] Weigh silicon powder (average particle size is 150nm), natural graphite, PVDF and acetylene black and disperse in N-methylpyrrolidone to make silicon-natural graphite slurry. The weight ratio of each component in the material is 80:10: 5:5.

[0076] The silicon-natural graphite slurry is coated on the copper current collector with a mask plate; then the mask plate is gently removed, leaving a cylindrical silicon-natural graphite on the copper current collector; then it is placed on the In a vacuum oven, bake at 120°C for 2 hours and take it out to obtain a copper current collector / (cylindrical silicon-natural graphite) electrode.

[0077] Weigh graphene, PTFE and acetylene black and disperse them in N-methylpyrrolidone to make graphene slurry. The weight ratio of each component i...

Embodiment 3

[0080] First, a square-hole mask plate with a thickness of 100 μm, a through-hole side length of 100 μm, and a center-to-hole distance of 160 μm was tightly attached to the nickel current collector. Weigh silicon powder (average particle size is 50nm), hard carbon, polyacrylonitrile and acetylene black and disperse in N-methylpyrrolidone to make silicon-hard carbon slurry. The weight ratio of each component in the material is 50: 40:5:5. Coat the silicon-hard carbon slurry on the nickel current collector with the mask plate; then gently remove the mask plate, leaving a square column-shaped silicon-hard carbon on the nickel current collector; then place it on the In a vacuum oven, bake at 120 degrees for 2 hours and take it out to obtain a nickel current collector / (square columnar silicon-hard carbon) electrode.

[0081] Weigh mesoporous carbon (average pore diameter about 5nm), PTFE and acetylene black and disperse them in N-methylpyrrolidone to make mesoporous carbon slurry....

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Abstract

The invention relates to a negative electrode for a lithium battery. The negative electrode for the lithium battery comprises a first active electrode substance moulded body and a second active electrode substance moulded body which are arranged on a negative current collector, wherein the first active electrode substance moulded body comprises a plurality of discrete moulding units; gaps betweenthe plurality of moulding units are filled with the second active electrode substance moulded body, and the second active electrode substance moulded body covers the surface of the first active electrode substance moulded body; the first active electrode substance moulded body contains a silicon material, and the second active electrode substance moulded body contains a carbon material. The invention further relates to a method for preparing the negative electrode by a mask method and the lithium battery. According to the negative electrode for the lithium battery, the moulding units of the silicon material are coated with the carbon material, the gaps between the moulding units are filled with the carbon material, and through the physical properties of the carbon material, the volume change of silicon during charge and discharge is absorbed and buffered, so that the technical problems such as electrode cracking, electrode crushing and separation from a conductive agent due to the volume change are relieved.

Description

technical field [0001] The invention relates to the technical field of lithium battery electrodes, in particular to a negative electrode for lithium batteries and a preparation method thereof. Background technique [0002] Since the advent of lithium-ion batteries in the 1990s, they have been widely used because of their high energy density, high operating voltage, high cycle times, and no memory effect. With the widespread use of various electronic products and electric vehicles, people have higher and higher requirements for battery life, and there is an urgent need to develop lithium-ion batteries with high energy density and long cycle life. Graphite is currently the most important negative electrode material in the market, but its specific capacity is low (only 372mAh / g), and its electrochemical performance is poor at high battery density, which limits the further improvement of the energy density of lithium-ion batteries. [0003] The silicon-based negative electrode ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/13H01M4/133H01M4/1393H01M4/62H01M10/0525
CPCH01M4/13H01M4/133H01M4/1393H01M4/625H01M10/0525Y02E60/10
Inventor 朱坤磊唐其伟池子翔苗力孝
Owner 桑德新能源技术开发有限公司
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