Core-Shell Cathode Material for Stable Sulfide Solid-State Batteries
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Solution Overview
Problem
Lithium all-solid-state batteries face issues such as irreversible properties and decreased capacity due to interfacial side reactions and non-uniform electrode charge distribution, along with low ionic conductivity, hindering their commercialization.
Innovation Solution
A positive electrode active material with a lithium metal oxide core and a shell of metal sulfide particles (M2S) is developed, where the metal sulfide particles are adsorbed on the surface to reduce interfacial resistance and side reactions, improving lithium ion mobility and charging-discharging capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a lithium metal sulfide positive electrode active material is used to increase capacity, then charge-discharge performance is greatly increased, but capacity retention rate at charge and discharge is significantly lower than oxide-based materials
Solution Approach 1:
The patent applies composite materials by combining lithium metal oxide core with a shell containing metal sulfide particles and metal oxide. This composite structure allows the core to provide high capacity while the shell maintains structural stability and prevents degradation, thereby achieving both high capacity and good capacity retention rate simultaneously
Solution Approach 2:
The patent applies local quality by creating a core-shell structure where different regions have different functions. The core contains lithium metal oxide for high capacity, while the shell contains metal sulfide particles and metal oxide for structural stability and protection. This local differentiation allows each region to optimize its specific function, resolving the contradiction between capacity and retention rate
2Reliability
If surface treatment with metal oxide is applied to improve charging and discharging performance, then performance improvement is achieved, but high raw material cost limits commercialization
Solution Approach 1:
The patent applies parameter changes by optimizing the particle size of metal sulfide particles to 0.1 nm to 40 nm and controlling their content at 0.1 to 2 wt%. These parameter optimizations allow the use of metal sulfide particles instead of expensive metal oxide surface treatment, achieving good charging and discharging performance while reducing raw material costs for commercialization
3Quantity of substance
If sulfide-based solid electrolyte is used to achieve high energy density, then energy density capacity storage is improved, but interfacial side reactions and low ionic conductivity hinder commercialization
Solution Approach 1:
The patent applies intermediary by introducing metal sulfide particles as a mediator at the interface between the lithium metal oxide core and sulfide-based solid electrolyte. This intermediary layer improves ionic conductivity and prevents harmful interfacial side reactions, allowing the system to maintain high energy density while achieving good interface stability and ionic conductivity
Solution Approach 2:
The patent applies composite materials by creating a core-shell structure with metal sulfide particles in the shell, which acts as a composite interface material between the lithium metal oxide core and sulfide-based solid electrolyte. This composite structure simultaneously improves ionic conductivity and prevents interfacial side reactions, resolving the contradiction between energy density and interface stability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The core-shell structure enhances lithium ion mobility and charging-discharging capacity while preventing cracks and side reactions, leading to improved electrical performance and potential commercial viability.
Implementation Method 1
a shell adsorbed on a surface of the core and including metal sulfide (M2S) particles
Data Source
AI summary
A positive electrode active material and an all-solid-state battery comprising the same are provided. The positive electrode active material comprises a shell containing metal sulfide particles having a specific range of particle size adsorbed on a surface of a core containing a lithium metal oxide, and reduces cracks generated between the positive electrode active material and a solid electrolyte and reactivity therebetween and thereby providing improved mobility of lithium ions and high charge-discharge capacity.