Composite Binder Composition for Secondary Battery
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Solution Overview
Problem
Conventional lithium battery binders face challenges in achieving high energy density and cycle life characteristics due to poor adhesiveness, flexibility, and dispersibility of electrode active materials and conducting agents, particularly at high temperatures.
Innovation Solution
A binder composition combining a first fluorine-containing binder with a polar functional group, a second fluorine-containing binder without a polar group, and a non-fluorine-containing binder with polymerized acryl and olefin monomers, enhancing adhesiveness, flexibility, and dispersibility of the electrode active material and conducting agent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the amount of binder is decreased to provide high energy density, then energy density is improved, but adhesiveness and flexibility of the electrode active material layer deteriorate
Solution Approach 1:
The invention uses a composite binder system comprising multiple fluorine-containing binders (with and without polar groups) and non-fluorine-containing binders in specific weight ratios. This composite approach allows the binder composition to provide both high adhesiveness to the current collector and good flexibility, enabling the use of lower overall binder content while maintaining electrode integrity and achieving high energy density.
Solution Approach 2:
The invention assigns different functional roles to different binder components: fluorine-containing binders with polar groups provide adhesiveness to the current collector, fluorine-containing binders without polar groups provide flexibility and dispersibility, and non-fluorine-containing binders supplement these properties. This localized functional distribution allows each binder type to optimize specific properties while working together to achieve overall high performance with reduced total binder content.
2Stability of the object's composition
If fluorine containing binder without polar group is used to maintain electrode structure, then electrode structure stability is improved, but dispersibility of conducting agent and adhesiveness to electrode plate deteriorate
Solution Approach 1:
The invention merges fluorine-containing binders without polar groups (which provide electrode structure stability) with fluorine-containing binders with polar groups (which provide dispersibility) and non-fluorine-containing binders (which provide adhesiveness and flexibility). This combination allows the electrode structure to be maintained while simultaneously achieving good dispersibility of conducting agents and adhesiveness to the electrode plate.
Data Source
AI summary
In an aspect, a binder composition, a cathode including the same, and a lithium battery including the cathode, wherein the binder composition includes a first fluorine containing binder including a polar functional group; a second fluorine containing binder not including a polar functional group; and a non-fluorine containing binder including a repeating unit resulting from polymerization of an acryl monomer and a repeating unit resulting from polymerization of an olefin monomer, wherein the first fluorine containing binder is a vinylidene fluoride containing binder is provided.