Lithium Oxide-Coated Cathode Material for Stable Solid-State Interfaces
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Solution Overview
Problem
Existing lithium secondary batteries face challenges with high interfacial resistance and side reactions at the interface between the cathode active material and solid electrolyte, limiting their stability and energy density.
Innovation Solution
A cathode active material with a lithium oxide coating is developed, comprising lithium and a first element with specific electrochemical stability properties, and a second element that substitutes part of the first element, enhancing electrochemical and interfacial stability, and is integrated with a sulfide-based solid electrolyte and conductive materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating layer is applied to the cathode active material to improve interfacial stability with solid electrolyte, then interfacial stability is improved, but device complexity increases
Solution Approach 1:
The patent applies composite materials by creating a coating layer with dual functionality: lithium oxide (Li2O) provides electrochemical stability while preventing side reactions, and aluminum oxide (Al2O3) provides interfacial stability with the solid electrolyte. This composite coating structure resolves the contradiction by combining materials with complementary properties to simultaneously improve reliability without excessive complexity
Solution Approach 2:
The coating layer acts as an intermediary between the cathode active material and the solid electrolyte. It mediates the interface by preventing direct contact and side reactions while maintaining stable ionic transport, thus improving interfacial stability without requiring complex structural modifications to the electrode itself
2Reliability
If a coating layer is applied to reduce side reactions at the interface, then electrochemical stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent employs parameter changes by controlling the thickness of the coating layer (1-10 nm) and the composition ratios of Li2O and Al2O3 to optimize both electrochemical stability and manufacturability. By adjusting these parameters, the coating provides sufficient protection against side reactions while remaining compatible with existing manufacturing processes
3Ease of manufacture
If all-solid-state battery structure is used to improve safety and simplify manufacturing, then ease of manufacture is improved, but interfacial resistance increases
Solution Approach 1:
The coating layer serves as an intermediary that reduces interfacial resistance between the cathode active material and solid electrolyte. It facilitates stable ionic transport and improves contact at the interface, thereby resolving the contradiction between the simplified all-solid-state structure and the need for low interfacial resistance
Data Source
AI summary
Provided is a cathode active material for lithium secondary batteries, featuring a core component with a coating part comprising lithium oxide. The lithium oxide includes lithium, a first element, and a second element substituting part of the first element. The first element can be boron (B), aluminum (Al), gallium (Ga), niobium (Nb), protactinium (Pa), or tantalum (Ta). The cathode active material demonstrates improved electrochemical stability and interfacial properties, with specified reduction and oxidation potentials. The lithium secondary battery comprises this cathode, an anode, and a solid electrolyte layer interposed between them. The core component may consist of lithium transition metal oxide in the form of secondary particles aggregating primary particles, providing enhanced performance. The solid electrolyte may be sulfide-based with an argyrodite crystal structure. The battery also includes a conductive material and a binder for improved functionality and stability.