Water adhesive for lithium ion battery, preparation method thereof and lithium ion battery positive plate

Abstract

The invention relates to aqueous bonding agent for lithium ion batteries, a preparation method and a positive plate for the lithium ion batteries, belonging to the energy storage device such as battery manufacturing field. The aqueous bonding agent for the lithium ion batteries provided by the invention is aqueous polymer emulsion formed after polyvinyl alcohol or ethylidene ether derivatives thereof is taken as a main polymer and two or more than two monomers with different polarities are taken as a graft comonomer to undergo a graft modification in water medium, the solid content of the emulsion is between 5 and 40 percent, and the viscosity is between 200 and 20000 centipoise (40 DEG C). The positive electrode prepared by the aqueous bonding agent for the lithium ion batteries of the invention has higher compacted density, so the volume energy density of the lithium ion batteries is improved; at the same time, the positive plate has good flexibleness after the drying, which contributes to the production of the batteries, improves the finished product rate of battery production, and solves the problems that the positive electrode of the lithium batteries has lower compacted density and the positive plate is brittle and has bad flexibleness after the drying.

Description

Technical field [0001] The invention relates to an adhesive for lithium ion batteries and a manufacturing method thereof, and belongs to the field of manufacturing energy storage devices such as batteries. Background technique [0002] Lithium-ion batteries have advantages that other batteries cannot match: high energy density, long life, small size, and no pollution. They are widely used in electric vehicles, aerospace, communication equipment, and various portable appliances. They are the most ideal mobile power source. [0003] Lithium-ion batteries are mainly composed of positive electrodes, negative electrodes, separators and non-aqueous electrolytes. The positive and negative electrodes are mixed and ground into a slurry by electroactive materials, conductive agents and binder solutions, which are then coated on the current collector. It is made of copper foil and aluminum foil, which are processed by drying, rolling and other processes. There are two main categories ...

AI Technical Summary

Problems solved by technology

[0004] The binder that uses fluorine-containing olefin polymer solution as the positive and negative electrode materials of lithium-ion batteries has two obvious disadvantages: 1. The volatilization of solvents during the electrode production process is easy to pollute the environment and affect the health of operators. There is greater harm; 2. It greatly increases the production cost of lithium-ion batteries, the solvent must be collected and processed with special refrigeration equipment, and fluoropolymers and their solvents are expensive

However, the use of it in the positive electrode has the following disadvantages: 1. The compacted density of the positive electrode is low, that is, under the same weight of the pole piece, the thickness of the pole piece is relatively large, which reduces the volume energy density of the lithium-ion battery; 2. The pole piece is dry The latter is brittle and poor in flexibility, and the pole piece is easy to break during the battery production process, which reduces the yield of battery production

[0007] So far, there is no ideal water-based binder for lithium-ion battery cathode powder materials.