Dual-Layer Solid Electrolyte Membrane for Strength and Ion Transport
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Solution Overview
Problem
Existing all-solid-state batteries face challenges in maintaining both high ionic conductivity and mechanical strength, with potential side reactions occurring at the interface between the solid electrolyte membrane and the negative electrode, which degrade battery performance.
Innovation Solution
A solid electrolyte membrane is designed with two layers, where the first layer contains a particulate binder and the second layer contains a fibrous binder, both manufactured without solvents, to enhance strength while minimizing side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid electrolyte membrane is used to improve safety, then fire safety is improved, but ionic conductivity is reduced
Solution Approach 1:
The patent uses a composite solid electrolyte membrane consisting of a sulfide-based solid electrolyte (providing high ionic conductivity) and a polymer binder (providing mechanical strength and safety). This composite structure allows the membrane to simultaneously achieve high ionic conductivity (≥10⁻⁴ S/cm at 25°C) and improved fire safety by eliminating flammable liquid electrolytes.
2Use of energy by moving object
If the ionic conductivity of the solid electrolyte is increased, then battery performance is improved, but mechanical strength is reduced
Solution Approach 1:
The patent employs a composite structure where sulfide-based solid electrolyte particles (providing ionic conductivity) are embedded in a polymer binder matrix (providing mechanical strength). The binder content is controlled at 1-10 wt% to balance ionic conductivity and mechanical properties, achieving both high performance and sufficient strength.
Solution Approach 2:
The patent optimizes the local distribution and content of the polymer binder within the solid electrolyte membrane. By controlling the binder concentration at 1-10 wt% and using specific binder materials (e.g., polyvinylidene fluoride, polyacrylonitrile), the membrane achieves localized mechanical reinforcement without compromising overall ionic conductivity.
3Strength
If a binder is added to improve the strength of the solid electrolyte membrane, then mechanical strength is improved, but side reactions at the interface with the negative electrode increase
Solution Approach 1:
The patent carefully controls the binder content parameter within the range of 1-10 wt% to minimize side reactions while maintaining mechanical strength. Additionally, the patent selects binder materials with specific chemical properties (low reactivity with lithium metal) and optimizes the molecular weight and composition parameters to reduce interfacial side reactions.
Solution Approach 2:
The patent uses a thin layer of binder material that serves its primary function of providing mechanical strength without significantly interfering with the electrochemical performance. The binder acts as a minimal necessary component that enables membrane integrity while minimizing harmful interfacial reactions.
Data Source
AI summary
Disclosed is a solid electrolyte membrane, a method for manufacturing the same, and an all-solid-state battery containing the same. More specifically, the solid electrolyte membrane includes a first solid electrolyte layer and a second solid electrolyte layer stacked adjacent to each other, and the first solid electrolyte layer has a structure in which particulate binders are dispersed, and the second solid electrolyte layer has a structure in which fibrous binders are entangled or connected to each other, and thus the strength may be improved without lowering the ionic conductivity of the solid electrolyte membrane. The solid electrolyte membrane may be substantially free of solvent.