Composite Coating for Positive Electrode Thermal Stability
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Solution Overview
Problem
Conventional all-solid-state batteries face challenges in achieving both thermal stability and low interfacial resistance in positive electrodes, as sulfide solid electrolytes offer low thermal stability and high deformability, while halide solid electrolytes provide high thermal stability but poor deformability, leading to conflicting performance metrics.
Innovation Solution
A coated positive electrode active material is developed, featuring a coating layer comprising both sulfide and halide solid electrolytes, which balances thermal stability and interfacial resistance by optimizing the volume proportion and composition of the halide solid electrolyte within the coating layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sulfide solid electrolyte is used in the positive electrode, then interfacial resistance is reduced due to high deformability, but thermal stability deteriorates
Solution Approach 1:
The patent applies composite materials by combining sulfide solid electrolyte and halide solid electrolyte in the positive electrode. The sulfide component provides low interfacial resistance through high deformability, while the halide component contributes high thermal stability. This composite structure resolves the contradiction by integrating the advantageous properties of both materials rather than selecting one over the other.
Solution Approach 2:
The patent implements local quality by creating a coating layer with specific composition on the positive electrode active material surface. The coating layer contains both sulfide and halide solid electrolytes in optimized proportions, where the sulfide phase locally reduces interfacial resistance at the electrode interface, while the halide phase locally enhances thermal stability. This spatial differentiation of material functions resolves the contradiction at the micro-scale interface structure.
2Temperature
If halide solid electrolyte is used in the positive electrode, then thermal stability is improved, but interfacial resistance increases due to poor deformability
Solution Approach 1:
The patent uses composite materials to combine halide solid electrolyte (providing thermal stability) with sulfide solid electrolyte (providing low interfacial resistance). The composite structure allows the halide component to dominate the thermal stability characteristics while the sulfide component mitigates the interfacial resistance issue through its deformability, thus resolving the contradiction.
Solution Approach 2:
The patent applies local quality by forming a coating layer where halide and sulfide solid electrolytes are distributed in specific proportions. The halide phase provides local thermal stability, while the sulfide phase locally reduces interfacial resistance at critical interfaces. This localized functional differentiation resolves the contradiction between thermal stability and interfacial resistance.
3Temperature
If a coating layer with both sulfide and halide solid electrolytes is formed, then thermal stability is enhanced, but device complexity increases
Solution Approach 1:
The patent applies composite materials by integrating sulfide and halide solid electrolytes into a single coating layer structure. While this enhances thermal stability through the halide component, it also increases device complexity due to the need to control the composition, phase distribution, and interface structure of the composite coating. The principle is used to achieve performance enhancement at the cost of increased structural complexity.
Data Source
AI summary
A coated positive electrode active material according to one aspect of the present disclosure includes a positive electrode active material and a coating layer coating at least a portion of a surface of the positive electrode active material. A positive electrode material according to one aspect of the present disclosure includes the coated positive electrode active material and a first solid electrolyte. A battery according to one aspect of the present disclosure includes: a positive electrode including the positive electrode material; a negative electrode; and an electrolyte layer provided between the positive electrode and the negative electrode.