Low-Temperature Sintering of Garnet Electrodes
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Solution Overview
Problem
The challenge is to produce a porous garnet-type ion-conducting oxide sintered body with high ion conductivity for electrodes and electrolyte layers, as existing methods face issues with achieving both high ion conductivity and porosity due to high sintering temperatures causing chemical reactions and abnormal grain growth.
Innovation Solution
A method involving the preparation of crystal particles of garnet-type ion-conducting oxides, a lithium-containing flux, and electrode active materials, where the particles are sintered at 650°C or less, with the flux having a larger particle diameter, allowing for solid phase flux reaction and low-temperature bonding, thereby forming a porous structure with controlled voidage and suppressing chemical reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high sintering temperature (1100°C) is used to obtain high ion conductivity, then ion conductivity is improved, but chemical reactions occur between electrode active material and oxide electrolyte causing degradation
Solution Approach 1:
The patent changes the sintering temperature parameter from conventional high temperature (1100°C) to low temperature (650°C or less), fundamentally altering the processing conditions to avoid chemical reactions while maintaining ion conductivity through alternative mechanisms
Solution Approach 2:
A lithium-containing flux is introduced as an intermediary substance with larger particle diameter than the garnet-type oxide particles. This flux mediates the bonding process at low temperatures, enabling particle aggregation and sintering without direct high-temperature contact between electrode active material and electrolyte that would cause harmful reactions
2Object-affected harmful factors
If low sintering temperature is used to prevent chemical reactions, then chemical stability is improved, but particle bonding is insufficient resulting in low ion conductivity
Solution Approach 1:
The lithium-containing flux acts as a eutectic intermediary that lowers the effective bonding temperature. The flux particles with larger diameter create a hierarchical structure that facilitates low-temperature sintering while maintaining adequate particle bonding and ion conductivity pathways
Solution Approach 2:
The patent creates a composite sintered body structure combining garnet-type ion-conducting oxide particles with lithium-containing flux particles. This composite approach enables low-temperature processing while achieving sufficient bonding and maintaining ion conductivity through the synergistic interaction of the two material phases
3Strength
If porosity is increased to suppress electrode cracking, then mechanical flexibility is improved, but ion conductivity may be reduced due to fewer continuous pathways
Solution Approach 1:
The patent intentionally creates a porous sintered body structure with controlled voidage, recognizing that porosity provides mechanical flexibility to accommodate electrode expansion and contraction while the specific pore structure and distribution maintain ion conductivity pathways
Solution Approach 2:
The low-temperature sintering process changes the densification behavior, allowing porosity to be retained at lower levels compared to high-temperature sintering. This enables the structure to maintain both mechanical flexibility and adequate ion conductivity pathways
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
This approach results in a porous electrode with high ion conductivity and reduced alteration of the electrode active material, enhancing battery performance and reducing production costs while maintaining structural integrity.
Implementation Method 1
sintering the electrolyte material and the electrode active material by heating at a temperature of 650° C. or less
Implementation Method 2
allowing for solid phase flux reaction and low-temperature bonding
Data Source
AI summary
A method for producing an electrode comprising a porous garnet-type ion-conducting oxide sintered body with high ion conductivity, the electrode, and an electrode-electrolyte layer assembly comprising the electrode and an electrolyte layer comprising a dense garnet-type ion-conducting oxide sintered body with high ion conductivity. Disclosed is a method for producing an electrode, the method comprising: preparing crystal particles of a garnet-type ion-conducting oxide; preparing a lithium-containing flux; preparing the electrode active material; preparing an electrolyte material by mixing the crystal particles of the garnet-type ion-conducting oxide and the flux; and sintering the electrolyte material and the electrode active material by heating at a temperature of 650° C. or less, wherein a number average particle diameter of the flux is larger than a number average particle diameter of the crystal particles of the garnet-type ion-conducting oxide.