Core-Shell Electrode Binder for Smooth Lithium-Ion Coatings
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Solution Overview
Problem
Conventional binders for lithium-ion battery electrodes exhibit insufficient applicability to current collectors, leading to low surface smoothness of the electrode active material layer and high internal resistance.
Innovation Solution
Employing core-shell particles with a rubber core and a shell layer formed from a polymer containing methacrylic acid units and (poly)alkylene glycol chain-containing (meth)acrylic ester units as the electrode binder, which enhances adhesion and reduces internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional binder is used in the electrode active material layer, then the adhesion between particles and current collector is maintained, but the applicability to current collector is insufficient and surface smoothness is low
Solution Approach 1:
The patent uses a composite binder system consisting of styrene/butadiene rubber (SBR) combined with carboxymethyl cellulose (CMC) or polyacrylic acid (PAA). This composite approach combines the adhesive properties of SBR with the coating performance and surface smoothness enhancement provided by the water-soluble polymers, resolving the contradiction between adhesion maintenance and applicability improvement.
Solution Approach 2:
The patent optimizes the molecular weight and concentration parameters of the water-soluble polymer additives (CMC or PAA) to achieve both good applicability and high surface smoothness. By adjusting these parameters, the slurry exhibits improved flow characteristics and coating behavior without compromising the adhesive function.
2Reliability
If conventional binder is used in the electrode active material layer, then adhesion is maintained, but internal resistance of the lithium-ion battery is high
Solution Approach 1:
The composite binder system of SBR combined with CMC or PAA creates a dual-function binder that maintains strong adhesion through SBR while the water-soluble polymer component improves slurry uniformity and electrode density, thereby reducing internal resistance and improving battery reliability.
Data Source
AI summary
An electrode binder for a lithium-ion battery includes core-shell particles each of which includes a core and a shell layer located outside the core. The core is formed of rubber, and the shell layer is formed of a shell-forming polymer containing at least one type of monomer units selected from the group consisting of methacrylic acid units and (poly)alkylene glycol chain-containing (meth)acrylic ester units. The proportion of the methacrylic acid units in the shell-forming polymer is from 5 to 40 wt% or the proportion of the (poly)alkylene glycol chain-containing (meth)acrylic ester units in the shell-forming polymer is from 10 to 30 wt%.