Flexible Sulfide Electrolyte Membrane for Crack-Resistant Solid Batteries
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Solution Overview
Problem
Current 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 result in safety issues like heat dissipation and explosion, and existing flexible polymer-based electrolytes have low ion conductivity and thermal stability.
Innovation Solution
A flexible sulfide solid electrolyte layer with an argyrodite lithium ion conducting material is developed by adjusting the bromine to chlorine ratio and using specific polymer binders, achieving a bending radius of no more than 4 cm and a bending strain of no less than 0.1%, while maintaining sufficient lithium-ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thiophosphate-based solid electrolyte is used, then high ionic conductivity is achieved, but mechanical flexibility is poor leading to cracks
Solution Approach 1:
The patent uses a composite structure consisting of an inorganic solid electrolyte layer (providing high ionic conductivity) and a flexible polymer layer (providing mechanical flexibility and crack resistance). This composite design allows the battery to maintain both high ionic conductivity and mechanical flexibility, preventing cracks during handling and operation.
Solution Approach 2:
The patent introduces a flexible polymer layer that acts as a protective shell over the inorganic solid electrolyte. This flexible layer can accommodate mechanical deformation without cracking, preventing the brittle inorganic electrolyte from developing defects while maintaining ion transport capability.
2Strength
If polymer-based flexible electrolyte is used, then mechanical flexibility is improved, but ion conductivity and thermal stability decrease
Solution Approach 1:
The patent creates a composite electrolyte system where the inorganic solid electrolyte provides high ion conductivity and thermal stability, while the polymer matrix provides flexibility. The synergistic combination allows the electrolyte to exhibit properties superior to either component alone, achieving both mechanical flexibility and high ionic conductivity.
Solution Approach 2:
The polymer layer acts as an intermediary that protects the inorganic solid electrolyte particles, maintaining their structural integrity while enabling flexible deformation. This intermediary layer prevents direct contact and potential damage between inorganic particles during mechanical stress, preserving ion conductivity pathways.
3Object-affected harmful factors
If SE layer is made rigid to prevent cathode-anode contact, then safety is improved, but mechanical flexibility is reduced causing handling issues
Solution Approach 1:
The patent employs a flexible polymer shell that conformally coats the inorganic solid electrolyte particles. This flexible shell maintains the structural integrity needed to prevent cathode-anode contact while allowing the battery to be bent and handled without causing defects in the electrolyte layer.
Solution Approach 2:
The composite structure combines rigid inorganic electrolyte particles (which maintain separation between electrodes) with a flexible polymer matrix (which enables handling). The rigid particles provide the barrier function while the flexible matrix provides the mechanical compliance needed for safe handling and deployment.
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.