Core-Shell Polymer Functional Layer for Battery Blocking Resistance
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Solution Overview
Problem
Existing non-aqueous secondary battery functional layers face challenges in achieving both high blocking resistance and process adhesiveness, particularly during the production and storage of wound-up battery members, leading to faults and reduced productivity.
Innovation Solution
A composition for a non-aqueous secondary battery functional layer using a particulate polymer with a core-shell structure, where the glass-transition temperatures of the core and shell portions are within specific ranges, and the mass proportion of the core portion is between 30% and 80%, providing both excellent blocking resistance and process adhesiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a functional layer is provided on the surface of an electrode and/or separator to improve heat resistance and strength, then the battery member's thermal stability and mechanical strength are improved, but blocking occurs during storage and transport in wound-up state, leading to reduced productivity
Solution Approach 1:
The patent applies parameter changes by carefully controlling the glass transition temperatures of the core and shell polymers, the mass proportion of the core portion (30-80%), and the particle size distribution of the particulate polymer. These parameter optimizations enable the functional layer to maintain shape at high temperatures (improving heat resistance) while preventing blocking during wound-up storage (improving productivity).
Solution Approach 2:
The patent uses composite materials by employing a particulate polymer with a core-shell structure, where the core provides heat resistance and the shell provides shape stability. This composite structure allows the functional layer to simultaneously achieve improved heat resistance, strength, and blocking resistance during storage and transport.
2Strength
If a functional layer is provided on the surface of an electrode and/or separator to improve adhesiveness between battery members, then the process adhesiveness is improved, but blocking occurs during storage and transport in wound-up state
Solution Approach 1:
The patent applies local quality by creating a functional layer with spatially differentiated properties through the core-shell structure. The core portion (with higher glass transition temperature) provides local heat resistance, while the shell portion (with lower glass transition temperature) provides local shape stability and adhesion. This local differentiation allows the layer to simultaneously achieve process adhesiveness and blocking resistance.
3Productivity
If a thermoplastic polymer layer is used as a functional layer to provide blocking resistance, then blocking resistance is improved, but process adhesiveness between battery members during production is insufficient
Solution Approach 1:
The patent optimizes parameters by selecting specific glass transition temperature ranges for the core (higher than shell) and shell polymers, controlling the core mass proportion at 30-80%, and adjusting particle size distribution. These parameter changes enable the functional layer to provide sufficient blocking resistance while maintaining adequate process adhesiveness during battery member production.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The functional layer effectively inhibits blocking and ensures high adhesiveness between battery members, enhancing the production efficiency and stability of non-aqueous secondary batteries by maintaining shape during storage and displaying sufficient adhesion under pressure.
Implementation Method 1
the core portion is formed from a polymer having a glass-transition temperature of higher than 25° C. and lower than 80° C.
Implementation Method 2
the shell portion is formed from a polymer having a glass-transition temperature of not lower than −80° C. and not higher than 25° C.
Data Source
AI summary
Provided is a composition for a non-aqueous secondary battery functional layer capable of forming a functional layer that can provide a battery member such as an electrode or a separator with both excellent blocking resistance and excellent process adhesiveness. The composition for a functional layer contains a particulate polymer A. The particulate polymer A has a core-shell structure including a core portion and a shell portion that at least partially covers an outer surface of the core portion. The core portion is formed from a polymer having a glass-transition temperature of higher than 25° C. and lower than 80° C. The shell portion is formed from a polymer having a glass-transition temperature of −80° C. to 25° C. The proportion constituted by the core portion among the total of the core portion and the shell portion is 30 mass % to 80 mass %.