All-Solid Battery Protective Layers for Side Reaction and Crack Control
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Solution Overview
Problem
Lithium batteries with solid electrolytes face issues such as side reactions between the sulfide-based solid electrolyte and the anode current collector, leading to reduced lifespan, and volume changes causing cracks and short circuits due to non-uniform pressure during charging and discharging.
Innovation Solution
An all-solid secondary battery design incorporating a cathode layer, an anode layer, and a solid electrolyte layer with a conductive carbon-based first protecting layer and a porous multilayer member as a second protecting layer to prevent side reactions and accommodate volume changes, reducing defects and improving durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sulfide-based solid electrolyte is used, then safety is improved, but side reactions with the copper current collector occur during charging and discharging
Solution Approach 1:
The patent introduces an intermediate protective layer between the sulfide-based solid electrolyte and the copper current collector. This intermediate layer acts as a mediator that prevents direct contact between the two materials, thereby eliminating side reactions while preserving the safety benefits of the solid electrolyte.
2Adaptability or versatility
If an elastic member is disposed on the anode layer to accommodate volume changes, then adaptability is improved, but air pockets form between the elastic member and anode layer causing non-uniform pressure
Solution Approach 1:
The patent employs a porous elastic member instead of a solid elastic member. The porous structure allows the elastic member to conform to the anode layer surface more effectively, eliminating air pockets and ensuring uniform pressure distribution while maintaining the ability to accommodate volume changes during charging and discharging.
3Reliability
If a solid electrolyte layer is used, then safety is improved, but cracks form in the solid electrolyte layer due to non-uniform pressure from anode volume changes
Solution Approach 1:
The patent applies a protective coating layer beforehand on the solid electrolyte layer to cushion against the non-uniform pressure generated by anode volume changes. This pre-applied protective layer prevents stress concentration that would otherwise lead to crack formation, thereby maintaining the integrity and safety of the solid electrolyte.
4Quantity of substance
If lithium plating occurs between solid electrolyte and anode current collector, then energy storage is improved, but non-uniform pressure causes defects and lithium growth leading to short circuits
Solution Approach 1:
The patent introduces a protective layer as an intermediary between the solid electrolyte and the anode current collector. This intermediate layer ensures uniform pressure distribution during lithium plating, preventing defect formation and uncontrolled lithium growth that would otherwise lead to short circuits, while still allowing effective lithium storage.
Data Source
AI summary
An all-solid secondary battery includes an electrode assembly including a cathode layer, an anode layer, and a solid electrolyte layer between the cathode layer and the anode layer, wherein the cathode layer includes a cathode current collector, the solid electrolyte layer includes a sulfide-based solid electrolyte, the anode layer includes an anode current collector, a first anode active material layer, and a first protecting layer between the anode current collector and the first anode active material layer, the electrode assembly includes a second protecting layer on one surface or both (e.g., opposite) surfaces thereof, the first protecting layer is a conductive coating layer including a carbon-based material, the second protecting layer includes a porous multilayer member, and the porous multilayer member includes a porous cushioning layer and a porous covering layer on one surface or both (e.g., opposite) surfaces of the porous cushioning layer.