Electrode assembly and lithium ion battery

A lithium-ion battery and electrode assembly technology, which is applied in the manufacture of electrode carriers/collectors, non-aqueous electrolyte batteries, and electrolyte batteries, and can solve problems such as low lithium utilization, affecting the DC impedance of lithium-ion batteries, and increasing the negative electrode impedance

Active Publication Date: 2020-07-07
CONTEMPORARY AMPEREX TECH CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Usually, an appropriate amount of lithium is directly covered on the surface of the negative electrode sheet to form a lithium metal layer, but after lithium is covered on the surface of the negative electrode sheet, part of the lithium will react with the air, resulting in a low utilization rate of lithium in the lithium metal layer. The battery life impro...

Method used

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  • Electrode assembly and lithium ion battery
  • Electrode assembly and lithium ion battery
  • Electrode assembly and lithium ion battery

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0073] (1) Preparation of positive pole piece

[0074] Mix the positive electrode active material lithium iron phosphate (the reversible gram capacity is 139mAh / g), the conductive agent acetylene black, and the binder PVDF at a mass ratio of 94:4:2, add the solvent N-methylpyrrolidone, stir and mix evenly to obtain The positive electrode slurry is then coated on both surfaces of the positive electrode current collector aluminum foil, then dried and cold pressed to obtain the positive electrode sheet, wherein the coating quality of the positive electrode slurry is 0.198g / 1540.25mm 2 (Based on mass excluding solvent).

[0075] (2) Preparation of negative pole piece

[0076] Mix graphite (reversible gram capacity of 340mAh / g) as the negative active material, conductive agent acetylene black, and binder SBR+CMC according to the mass ratio of 95:1.5:3.1:0.4, add solvent deionized water, fully stir and mix evenly to obtain The negative electrode slurry is then coated on both surfa...

Embodiment 2

[0094] The preparation process of the lithium-ion battery is the same as in Example 1, the difference is that in the preparation of the negative electrode sheet, several wavy strip-shaped lithium foils are replaced with thin strip-shaped lithium foils and are laminated at equal intervals by rolling. On the surface of the negative electrode active material layer, discontinuous metal lithium layers distributed at intervals are formed.

[0095] Among them, the mass of lithium metal layer is 3.05mg / 1540.25mm 2 , the width of each slender lithium foil is 0.5 mm, the distance between two adjacent slender lithium foils is 0.5 mm, the angle between the length direction of each slender lithium foil and the length direction of the negative electrode sheet are about 85°, and along the length direction of each elongated lithium foil, the surface of the negative electrode active material layer is completely covered by the lithium foil.

Embodiment 3

[0097] The preparation process of the lithium-ion battery is the same as in Example 1, the difference is that in the preparation of the negative electrode sheet, several wavy strip-shaped lithium foils are replaced with strip-shaped lithium foils and are composited to the negative electrode at equal intervals by rolling. On the surface of the active material layer, discontinuous metal lithium layers distributed at intervals are formed.

[0098] Among them, the mass of lithium metal layer is 3.05mg / 1540.25mm 2 , the width of each strip-shaped lithium foil is 0.5mm, the distance between two adjacent strip-shaped lithium foils is 0.5mm, and the included angle between the length direction of each strip-shaped lithium foil and the length direction of the negative electrode sheet is about 92°, and along the length direction of each strip-shaped lithium foil, the surface of the negative electrode active material layer is completely covered by the lithium foil.

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Abstract

The invention provides an electrode assembly and a lithium ion battery. The electrode assembly comprises a positive pole piece, an isolating membrane and a negative pole piece, wherein the negative pole piece comprises a negative current collector and a negative active material layer, and further comprises a metal lithium layer, the metal lithium layer is formed by a plurality of regular or irregular strip-shaped lithium-rich areas, and the plurality of lithium-rich areas are distributed at intervals in the length direction of the negative pole piece in a non-continuous form. The electrode assembly also satisfies the following conditions: the ratio of the negative electrode capacity per unit area to the positive electrode capacity per unit area is 1.2-2.1, and the ratio of the negative electrode capacity per unit area to the sum of the positive electrode capacity per unit area and 80% of the capacity of the metal lithium layer on the surface of the negative electrode active material layer per unit area is greater than or equal to 1.10. The lithium ion battery disclosed by the invention has relatively high lithium supplementing efficiency and relatively low direct-current impedance,and meanwhile, the lithium ion battery also has long cycle life and storage life.

Description

technical field [0001] The invention relates to the battery field, and more specifically relates to an electrode assembly and a lithium ion battery. Background technique [0002] Among secondary batteries, compared with other types of secondary batteries, lithium-ion batteries occupy a mainstream position in the market due to their higher energy density advantages. Among them, lithium-ion batteries with lithium iron phosphate as the positive electrode active material are widely used in electric bus power systems due to their high safety, low cost, and long life, and have broad application prospects in the field of large-scale energy storage. [0003] In recent years, based on the cost of electricity, the requirements for the life of lithium-ion batteries have become higher and higher. Due to the dissolution-repair equilibrium of the solid-electrolyte interface film (SEI film) on the surface of the graphite anode, the active lithium available for shuttle between the anode an...

Claims

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Application Information

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IPC IPC(8): H01M4/66H01M4/38H01M10/0525H01M4/70
CPCH01M4/667H01M4/382H01M10/0525H01M4/70Y02E60/10H01M2010/4292H01M2004/027H01M4/587H01M4/386H01M4/387H01M4/133H01M4/134H01M4/366H01M10/058H01M10/049H01M4/049H01M4/0447Y02P70/50H01M4/136H01M4/5825
Inventor 杨龙飞王国宝刘晓梅刘江林永寿赵丰刚
Owner CONTEMPORARY AMPEREX TECH CO
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