Solid-State Battery Interface Layers for Peeling-Resistant Cycling
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Solution Overview
Problem
All-solid-state secondary batteries face challenges in maintaining sufficient bonding between electrode layers, leading to peeling issues and deteriorated cycle characteristics due to the destruction of sintering additives during repeated charging and discharging.
Innovation Solution
Incorporating lithium vanadium phosphate and lithium zirconium phosphate as active materials, with intermediate layers containing zirconium and vanadium concentration gradients to enhance bonding between the electrode layers, reducing interfacial stress and peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If sintering additive is used to strengthen bonding between layers, then bonding strength is improved, but cycle characteristics deteriorate due to destruction of sintering additive during repeated charging and discharging
Solution Approach 1:
An intermediate layer containing lithium zirconium phosphate and lithium vanadium phosphate is introduced between the solid electrolyte layer and the positive/negative electrode active material layers. This intermediate layer acts as a mediator that provides stable bonding without relying on sintering additives, thereby maintaining both strong adhesion and excellent cycle characteristics during repeated charging and discharging.
Solution Approach 2:
The intermediate layer is formed using a composite material system comprising lithium zirconium phosphate and lithium vanadium phosphate. This composite structure combines the benefits of both materials to achieve stable bonding and resist destruction during cycling, resolving the contradiction between initial bonding strength and long-term reliability.
2Productivity
If different materials are fired at the same time to enable mass production, then manufacturing efficiency is improved, but bonding between positive electrode layer, negative electrode layer, and solid electrolyte layer becomes difficult
Solution Approach 1:
The intermediate layer is specifically positioned only at the interfaces where bonding is critical (between solid electrolyte and electrode active materials), while other regions maintain their original material properties. This localized approach enables simultaneous firing of different materials while ensuring strong bonding at the critical interfaces through the intermediate layer.
Data Source
AI summary
An all-solid-state secondary battery includes: a positive electrode active material layer; a negative electrode active material layer; and a solid electrolyte layer located between the positive electrode active material layer and the negative electrode active material layer, wherein at least one of the positive electrode active material layer and the negative electrode active material layer contains lithium vanadium phosphate, the solid electrolyte layer contains lithium zirconium phosphate, and between the positive electrode active material layer or the negative electrode active material layer containing lithium vanadium phosphate and the solid electrolyte layer, a first intermediate layer, which contains lithium vanadium phosphate containing zirconium and is located on the side of the positive electrode active material layer or the negative electrode active material layer, and a second intermediate layer, which contains lithium zirconium phosphate containing vanadium and is located on the side of the solid electrolyte layer, are provided.