Flexible Sulfide Solid Electrolyte for Crack-Resistant Solid-State Batteries
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Solution Overview
Problem
Existing thiophosphate-based solid electrolytes in all-solid-state batteries lack mechanical flexibility, leading to potential cracks and electronic contact between cathode and anode, which can cause safety issues.
Innovation Solution
A flexible sulfide solid electrolyte layer is developed by adjusting the bromine to chlorine ratio (Br/Cl) and incorporating specific elements and binders, resulting in a membrane with a bending radius of no more than 4 cm and a bending strain of no less than 0.1%, ensuring flexibility without cracks or wrinkles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thiophosphate-based solid electrolyte is used to achieve high ionic conductivity, then ion transportation is improved, but mechanical flexibility deteriorates leading to cracks and wrinkles
Solution Approach 1:
The patent changes the chemical composition parameters of the solid electrolyte by incorporating halogen elements (Cl, Br, I) into the thiophosphate structure. This compositional modification allows the material to maintain high ionic conductivity while improving mechanical flexibility and reducing crack formation during handling and operation.
Solution Approach 2:
The patent creates a composite solid electrolyte structure by combining thiophosphate base material with halogen elements. This composite approach enables the material to simultaneously achieve high ionic conductivity from the thiophosphate structure and enhanced mechanical flexibility from the halogen incorporation, resolving the contradiction between electrical and mechanical properties.
2Volume of moving object
If solid electrolyte layer is made thinner to improve battery energy density, then volume is reduced, but mechanical strength deteriorates increasing risk of electronic contact between electrodes
Solution Approach 1:
By modifying the chemical composition to include halogen elements, the patent changes the intrinsic mechanical properties of the solid electrolyte. This allows the electrolyte to be made thinner for higher energy density while the enhanced mechanical flexibility from halogen incorporation prevents crack formation and maintains sufficient strength to avoid electronic contact between electrodes.
3Reliability
If conventional solid electrolyte is used to prevent electronic contact, then safety is improved, but mechanical flexibility deteriorates causing handling damage
Solution Approach 1:
The patent modifies the chemical composition parameters of the solid electrolyte by incorporating halogen elements, which fundamentally changes the material's mechanical properties. This composition change enables the electrolyte to be more flexible and easier to handle during assembly and operation, while still maintaining its safety function of preventing electronic contact between electrodes.
Solution Approach 2:
By creating a composite structure with halogen-incorporated thiophosphate, the patent achieves a material that combines the safety characteristics of conventional solid electrolytes with improved mechanical flexibility. The composite nature allows simultaneous achievement of handling ease and safety functionality.
Data Source
AI summary
This disclosure relates to a flexible membrane of sulfide solid electrolyte. In one embodiment, the flexible membrane has a bending strain of no less than 0.1%. In one embodiment, the flexible membrane has a lithium-ion conductivity of no less than 0.5 mS/cm. The bending strain is calculated according to the formula εM=h/(2r), wherein h is thickness of the membrane and r is a bending radius corresponding to the membrane without any observable kinks, wrinkles, cracks, or damages.