Flexible Solid Electrolyte Composition for Battery Volume Changes
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Solution Overview
Problem
Conventional sulfide solid electrolytes in all-solid-state batteries lack flexibility, leading to poor interfacial bondability and inadequate followability to volume expansion and contraction during charge and discharge.
Innovation Solution
A compound with an acyclic phosphazene structure, containing a repeating unit represented by formula (1) and incorporating lithium and chalcogen atoms, is developed, which can be used to create a flexible solid electrolyte material and composition, including a halogen-containing compound and a disulfide bond, enhancing interfacial bondability and volume expansion/contraction tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sulfide solid electrolytes are used, then ionic conductivity is achieved, but flexibility is poor and interfacial bondability is insufficient
Solution Approach 1:
The patent creates a composite solid electrolyte by combining sulfide solid electrolyte particles with a flexible binder polymer matrix. The binder polymer contains both rigid segments (for maintaining ionic conductivity pathways) and flexible segments (for providing elasticity and followability). This composite structure allows the electrolyte to maintain good ionic conductivity while gaining flexibility to adapt to electrode volume changes during battery cycling.
Solution Approach 2:
The binder polymer is designed with local quality differentiation through its dual-segment structure: rigid segments provide localized structural support and ionic conduction pathways, while flexible segments provide localized adaptability and followability. This local differentiation allows different regions of the electrolyte to perform different functions simultaneously, resolving the contradiction between ionic conductivity and flexibility.
2Reliability
If conventional sulfide solid electrolytes are used, then electrochemical performance is achieved, but mixing property with active material is poor
Solution Approach 1:
The patent changes the physical and chemical parameters of the solid electrolyte system by introducing a polymer binder matrix. This transforms the electrolyte from a rigid particulate system to a flexible composite system with improved wettability and adhesion. The binder polymer modifies the interface properties between electrolyte and active material, enabling better mixing and interfacial contact while preserving the electrochemical performance of the sulfide particles.
3Reliability
If conventional sulfide solid electrolytes are used, then battery function is achieved, but followability to volume expansion and contraction is insufficient
Solution Approach 1:
The patent introduces dynamic characteristics to the solid electrolyte by using a flexible binder polymer with elastic properties. This allows the electrolyte to dynamically adapt its shape and volume in response to electrode expansion and contraction during battery cycling. The flexible segments of the binder polymer enable the electrolyte to follow electrode volume changes without compromising the electrochemical function, resolving the contradiction between maintaining battery function and achieving followability.
Data Source
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AI summary
Provided is a compound comprising repeating units represented by formula (1) as a noncydic structure. (In formula (1), X1 is a chalcogen atom. R is a hydrogen atom or a substitution group.)