Sulfide Solid Electrolyte Heat Treatment for Moisture-Stable Ion Conduction
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Solution Overview
Problem
Existing solid electrolytes in all-solid-state batteries face challenges such as low ion conductivity, interface resistance with solid particles, and deterioration of ion conduction performance due to depletion layers formed during solid-to-solid bonding.
Innovation Solution
A solid electrolyte with a uniform particle size distribution, high crystallinity, and high ion conductivity is developed by mixing sulfide-based solid electrolyte particles with lithium-metal-oxide and performing heat treatment at 250 °C to 350 °C, which improves moisture stability and suppresses particle aggregation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If solid-to-solid bonding is used to improve battery structure, then mechanical stability is improved, but ion conduction performance deteriorates due to depletion layer formation
Solution Approach 1:
The patent introduces a buffer layer as an intermediary substance between the solid electrolyte and the positive electrode active material particles. This buffer layer prevents direct solid-to-solid contact that would create depletion layers, thereby maintaining ion conduction performance while preserving mechanical stability. The buffer layer acts as a mediator that facilitates ion transport without forming harmful depletion zones at the interface.
Solution Approach 2:
The patent modifies the interface properties by introducing a buffer layer with specific compositional parameters (containing B, Nb, Zr, or their combinations). This changes the physical and chemical parameters at the solid electrolyte-electrode interface, preventing depletion layer formation and maintaining high ion conductivity while preserving mechanical integrity.
2Reliability
If buffer layer is formed on positive electrode active material particles to improve ion conduction, then ion conduction performance is improved, but manufacturing complexity increases and mass production becomes difficult
Solution Approach 1:
The patent combines the buffer layer formation process with the existing electrode manufacturing process. The buffer layer is formed by mixing the positive electrode active material with buffer layer forming agents and then sintering, which integrates multiple functions (electrode formation and buffer layer creation) into a single manufacturing step, enabling mass production while maintaining ion conduction performance.
Solution Approach 2:
The patent specifies particular compositional parameters for the buffer layer (containing B, Nb, Zr, or combinations) and controlled sintering conditions to achieve the desired properties. By optimizing these parameters, the buffer layer can be formed with appropriate thickness and composition that ensures ion conduction while being compatible with standard manufacturing processes.
3Reliability
If conventional coating methods are used to improve interface properties, then ion conduction is improved, but environmental problems and coat issues arise
Solution Approach 1:
The patent replaces conventional wet coating methods with a dry sintering process. Instead of applying coatings through liquid vehicles that may cause environmental issues and coating defects, the buffer layer is formed by mixing powders and sintering, which is a dry, environmentally friendly process that eliminates solvent-related problems and coat issues while achieving the desired interface properties.
Solution Approach 2:
The sintering process is conducted in an inert atmosphere (nitrogen or argon), which prevents oxidation and other unwanted chemical reactions during buffer layer formation. This inert environment eliminates environmental contamination and ensures high purity of the buffer layer, avoiding the environmental problems associated with conventional coating methods.
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 resulting solid electrolyte exhibits improved ion conductivity, moisture stability, and appropriate particle size distribution, enhancing the capacity characteristics, initial charge/discharge efficiency, and cycle-life characteristics of batteries.
Implementation Method 1
performing heat treatment at 250 °C to 350 °C
Implementation Method 2
high crystallinity
Data Source
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AI summary
Disclosed are a solid electrolyte and a method for preparing the same, the solid electrolyte includes sulfide-based solid electrolyte particles and the lithium-metal-oxide on the surface of the particles, wherein in an X-ray diffraction (XRD) analysis of the solid electrolyte, a full width at half maximum (FWHM) of a main peak is less than or equal to 0.160.