Garnet Solid Electrolyte Composition for Stable Electron Conductivity
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Solution Overview
Problem
Conventional solid-state batteries using garnet-type solid electrolyte ceramics face issues with impurity generation at grain boundaries, leading to increased electron conductivity, short-circuit phenomena, and leakage current during operation.
Innovation Solution
A solid electrolyte ceramic with a chemical composition represented by AαBβDγOω, where A includes Li, B includes La, and D includes transition elements capable of six-coordinate oxygen binding, is developed. This ceramic has a garnet-type crystal structure and includes specific ranges for α, β, γ, and ω, along with transition metal elements like Co, Ni, Mn, and Fe, to suppress electron conductivity increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a garnet-type solid electrolyte ceramic containing Bi is used to achieve higher ion conductivity, then ion conductivity is improved, but impurity such as Li-Bi-O-based compound is generated at grain boundary during operation, which increases electron conductivity and causes short-circuit or leakage current
Solution Approach 1:
The patent introduces a dual-dopant system where Ta5+ and Nb5+ act as intermediary elements that suppress the formation of Li-Bi-O impurity phases at grain boundaries. These dopants modify the chemical environment at grain boundaries, preventing the reduction reactions that would otherwise generate electron-conductive impurities during battery operation.
Solution Approach 2:
The patent modifies the chemical composition parameters by incorporating specific ratios of Ta5+ and Nb5+ dopants alongside Bi. This compositional parameter change fundamentally alters the electrochemical stability window and prevents the formation of electron-conductive impurity phases while maintaining high ion conductivity through the garnet structure.
2Use of energy by moving object
If the solid electrolyte composition is optimized for high ion conductivity, then ion conductivity is improved, but the stability of electron conductivity during operation deteriorates due to impurity formation
Solution Approach 1:
The patent creates a composite solid electrolyte material that integrates multiple functional components: Bi for high ion conductivity, Ta5+ and Nb5+ dopants for grain boundary stabilization and impurity suppression. This composite approach achieves both high ion conductivity and stable electron conductivity by combining the beneficial effects of different elements while mitigating their individual drawbacks.
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 solid electrolyte ceramic achieves excellent ion conductivity while effectively suppressing the increase in electron conductivity during battery operation, thereby preventing short-circuits and leakage currents.
Implementation Method 1
the solid electrolyte layer includes a solid electrolyte ceramic, and serves for ion conduction between the positive electrode layer and the negative electrode layer
Data Source
AI summary
A solid electrolyte ceramic having a chemical composition represented by: AαBβDγOω wherein A represents one or more of Li, Ga, Al, Mg, Zn, and Sc, and A includes at least Li; B represents one or more of La, Ca, Sr, Ba, and lanthanoid elements, and B includes at least La; and D represents one or more of transition elements capable of being six-coordinate with oxygen and elements belonging to Groups 12 to 15; and one or more of Co, Ni, Mn, and Fe, the solid electrolyte ceramic having a garnet-type crystal structure where: 139≤Y<150 in a range of 330<X≤370 wherein X (mol %) represents a content of the Li and Y (mol %) represents a content of the one or more elements represented by B when a content of the one or more elements represented by D in the general formula is 100 mol %.