Non-aqueous Battery Functional Layer Binder Composition
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Solution Overview
Problem
Non-aqueous secondary batteries face challenges in achieving high performance due to insufficient heat contraction resistance and vibration drop-off resistance of their functional layers, particularly when exposed to harsh conditions and electrolyte solutions.
Innovation Solution
A composition for a non-aqueous secondary battery functional layer is developed, combining a water-soluble polymer with a (meth)acrylamide monomer unit and a water-insoluble polymer containing an ethylenically unsaturated carboxylic acid and aromatic monovinyl monomer units, enhancing vibration drop-off resistance and heat contraction resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a functional layer is formed using conventional compositions to improve heat resistance and strength, then the structural integrity is enhanced, but the vibration drop-off resistance deteriorates when immersed in electrolyte solution
Solution Approach 1:
The patent uses a composite binder system comprising both water-soluble polymer (e.g., carboxymethyl cellulose) and water-insoluble polymer (e.g., polyvinylidene fluoride). This composite approach combines the thermal stability and binding capability of water-soluble polymers with the mechanical strength and vibration resistance of water-insoluble polymers, achieving both heat resistance and vibration drop-off resistance simultaneously.
2Power
If the functional layer is designed to improve output characteristics by reducing resistance, then electrical performance is enhanced, but heat contraction resistance deteriorates under high-temperature conditions
Solution Approach 1:
The patent optimizes the molecular weight, composition ratio, and crosslinking degree of the binder polymers to achieve a balance between electrical conductivity and thermal stability. By carefully controlling the water-to-oil soluble polymer ratio and their respective molecular weights, the functional layer maintains low resistance for high output while resisting heat-induced contraction.
3Ease of manufacture
If a single-type polymer binder is used to simplify the composition, then manufacturing complexity is reduced, but both vibration drop-off resistance and heat contraction resistance cannot be sufficiently improved
Solution Approach 1:
The patent employs a dual-polymer binder system where water-soluble polymers (providing heat resistance and binding) are combined with water-insoluble polymers (providing mechanical strength and vibration resistance). This composite strategy, while slightly increasing formulation complexity, achieves superior simultaneous performance in both vibration drop-off resistance and heat contraction resistance that single polymers cannot deliver.
Data Source
AI summary
A composition for a non-aqueous secondary battery functional layer comprises: non-conductive particles; a water-soluble polymer containing a (meth)acrylamide monomer unit in a proportion of 70.0 mass% or more and 99.0 mass% or less; and a water-insoluble polymer containing an ethylenically unsaturated carboxylic acid monomer unit in a proportion of 1.5 mass% or more and 5.0 mass% or less and having a degree of swelling in electrolyte solution of more than 1.0 time and 3.0 times or less.