Composition for non-aqueous secondary battery functional layer, non-aqueous secondary battery member, and non-aqueous secondary battery
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Solution Overview
Problem
Secondary batteries face challenges in maintaining performance at low temperatures and preventing post-cycling swelling, which affects charge carrier acceptance and battery stability.
Innovation Solution
A composition for a non-aqueous secondary battery functional layer is developed, comprising a block copolymer with specific aromatic and aliphatic conjugated diene units, non-conductive inorganic particles, and a solvent, which forms a functional layer that inhibits swelling and enhances charge carrier acceptance at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional binders and inorganic particles are used in functional layer composition, then manufacturing is straightforward, but post-cycling swelling occurs and charge carrier acceptance at low temperatures is poor
Solution Approach 1:
The patent uses a block copolymer composed of multiple monomer units (aromatic vinyl monomer unit, aliphatic conjugated diene monomer unit with carbon number 5 or more, and hydrogenated aliphatic conjugated diene monomer unit with carbon number 5 or more) as a binder in the functional layer composition. This composite polymer structure provides both swelling inhibition and improved charge carrier acceptance at low temperatures, resolving the contradiction between reliability and device complexity by integrating multiple functions into a single binder material.
2Quantity of substance
If electrode active material particles are used to enhance battery capacity, then energy density increases, but charge carrier acceptance at low temperatures deteriorates
Solution Approach 1:
The patent specifies precise compositional parameters for the block copolymer binder, including the proportion of each monomer unit (aromatic vinyl, aliphatic conjugated diene with C≥5, and hydrogenated aliphatic conjugated diene with C≥5). By optimizing these chemical composition parameters, the binder maintains effective charge carrier acceptance at low temperatures even when electrode active material particles are present, resolving the contradiction between quantity of substance and reliability.
3Ease of manufacture
If functional layer composition is simplified, then ease of manufacture improves, but ability to inhibit swelling and enhance low-temperature performance is reduced
Solution Approach 1:
The block copolymer binder is designed to perform multiple functions simultaneously: it binds electrode active material particles, inhibits post-cycling swelling, and enhances charge carrier acceptance at low temperatures. This multi-functional binder reduces the need for additional additives or complex composition formulations, thereby improving ease of manufacture while maintaining high reliability and battery performance across different temperature conditions.
Data Source
AI summary
Provided is a composition for a functional layer capable of forming a functional layer that can both inhibit post-cycling swelling of a secondary battery and increase charge carrier acceptance of the secondary battery at low temperatures. The composition for a functional layer contains non-conductive inorganic particles, a solvent, and a block copolymer including a block region formed of an aromatic vinyl monomer unit and a block region formed of either or both of an aliphatic conjugated diene monomer unit having a carbon number of 5 or more and a hydrogenated aliphatic conjugated diene monomer unit having a carbon number of 5 or more.