Buffered Composite Cathode for Sulfide Solid-State Interfaces
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Solution Overview
Problem
The interfacial resistance between sulfide solid electrolytes and cathodes in all-solid-state batteries is significantly increased due to side reactions, leading to degraded cycle and rate characteristics.
Innovation Solution
A composite cathode active material is developed with a nickel lithium transition metal oxide core and buffer layers comprising specific metal oxides, which are conformally coated to minimize side reactions and enhance stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If sulfide solid electrolyte is used in all-solid-state battery, then energy density and safety are improved, but interfacial resistance increases due to side reactions
Solution Approach 1:
A buffer layer comprising metal oxide is introduced as an intermediary between the sulfide solid electrolyte and the cathode active material. This buffer layer acts as a mediator that prevents direct contact and side reactions between the sulfide solid electrolyte and the cathode, thereby reducing interfacial resistance while maintaining the energy density benefits of the sulfide-based system.
Solution Approach 2:
The cathode structure is designed as a composite material system consisting of the cathode active material, the sulfide solid electrolyte, and the metal oxide buffer layer. This composite structure combines the high energy density characteristics of sulfide solid electrolytes with the protective and conductive properties of the metal oxide buffer layer, resolving the contradiction between energy density and interfacial resistance.
2Reliability
If buffer layer is added to reduce interfacial resistance, then reaction stability is improved, but device complexity increases
Solution Approach 1:
The buffer layer is applied locally only at the interface between the cathode active material and the sulfide solid electrolyte, rather than throughout the entire battery structure. This localized approach provides the necessary reaction stability and interfacial protection while minimizing the increase in overall device complexity and maintaining structural simplicity in other regions.
Data Source
AI summary
A composite cathode active material for an all-solid-state battery including a sulfide solid electrolyte, a preparation method thereof, a cathode layer for an all-solid-state battery, and an all-solid-state battery including the cathode layer, the composite cathode active material including a secondary particle including a plurality of primary particles; and a buffer layer on a surface of the secondary particle, wherein the secondary particle includes a nickel lithium transition metal oxide represented by Formula 1 (LiaNi1-bMbO2), the buffer layer includes a first buffer layer adjacent to a surface of the secondary particle and including an oxide represented by Formula 2 (LixAyOz); and a second buffer layer including an oxide represented by Formula 3 (LixEyOz).