Garnet Solid Electrolyte Ceramic for Suppressing Electron Conduction
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Solution Overview
Problem
Conventional solid-state batteries using garnet-type solid electrolyte ceramics with Bi exhibit increased electron conductivity during operation, leading to potential short-circuiting and leakage currents due to the generation of Li—Bi—O-based compounds at grain boundaries.
Innovation Solution
A solid electrolyte ceramic composition containing lithium (Li), lanthanum (La), bismuth (Bi), and one or more transition metal elements like cobalt (Co), nickel (Ni), or manganese (Mn) with a garnet-type crystal structure, which suppresses the increase in electron conductivity while maintaining high ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a garnet-type solid electrolyte ceramic containing Bi is used to achieve higher ionic conductivity, then ion conductivity is improved, but electron conductivity increases during operation leading to short-circuiting and leakage currents
Solution Approach 1:
The patent changes the chemical composition parameters by introducing transition metal elements (Co, Ni, Mn) to replace part of the Bi content in the garnet-type solid electrolyte ceramic. This compositional parameter change suppresses the formation of Li-Bi-O compounds at grain boundaries, thereby preventing the increase in electron conductivity during battery operation while maintaining high ionic conductivity through the garnet structure.
Solution Approach 2:
The patent creates a composite solid electrolyte ceramic by combining multiple elements (Li, La, Co/Ni/Mn, O) in specific ratios within the garnet-type crystal structure. This composite material approach allows the solid electrolyte to simultaneously achieve high ionic conductivity through the garnet framework while suppressing harmful electron conductivity by controlling the distribution and oxidation states of transition metal elements at grain boundaries.
2Productivity
If Bi is added to the solid electrolyte ceramic to improve ionic conductivity, then ion transport is enhanced, but Li-Bi-O compounds form at grain boundaries causing electron conduction
Solution Approach 1:
The patent modifies the chemical composition by limiting Bi content and introducing transition metal elements (Co, Ni, Mn) at specific concentration ranges (0.01-5.0 mol%). This parameter optimization prevents excessive Bi accumulation at grain boundaries that would form conductive Li-Bi-O compounds, while maintaining sufficient ionic conductivity through the garnet structure.
Solution Approach 2:
The transition metal elements (Co, Ni, Mn) act as intermediary substances that modify the chemical environment at grain boundaries. These intermediaries suppress the formation of Li-Bi-O compounds by altering local oxidation states and competing for oxygen vacancies, thereby preventing electron conduction pathways while allowing ionic transport through the bulk garnet structure.
3Duration of action of stationary object
If the solid electrolyte ceramic operates for extended periods, then battery function is maintained, but electron conductivity increases causing leakage currents and short-circuits
Solution Approach 1:
The patent applies preliminary action by incorporating transition metal elements (Co, Ni, Mn) into the solid electrolyte ceramic composition before battery operation begins. This pre-modification of the grain boundary chemistry prevents the formation of electron-conductive Li-Bi-O compounds during subsequent operation, thereby eliminating the source of leakage currents and short-circuits before they can develop.
Solution Approach 2:
The transition metal elements perform preliminary anti-action by suppressing the reduction reactions that would otherwise generate electron-conductive species at grain boundaries during battery operation. By controlling the oxidation states of Co, Ni, or Mn at grain boundaries, the patent preemptively counteracts the formation of electron conduction pathways, maintaining electrical stability throughout the battery's service life.
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 proposed ceramic effectively reduces electron conductivity issues, preventing short-circuiting and leakage currents, and ensures stable battery performance by incorporating transition metals that control the Bi distribution and oxidation states within the ceramic structure.
Implementation Method 1
the solid electrolyte layer contains a solid electrolyte ceramic, and is responsible for conduction of ions between the positive electrode layer and the negative electrode layer
Data Source
AI summary
A solid electrolyte ceramic containing: at least lithium (Li), lanthanum (La), bismuth (Bi), and oxygen (O) and having a garnet-type crystal structure; and one or more transition metal elements selected from the group consisting of cobalt (Co), nickel (Ni), and manganese (Mn).