Li-Bi Solid Electrolyte Composition for Low-Temperature Sintering
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Solution Overview
Problem
Conventional all solid state batteries require high-temperature firing, which can lead to the loss of elements like Li, resulting in reduced ionic conductivity, necessitating a solid electrolyte material that can achieve high ionic conductivity at lower temperatures.
Innovation Solution
A solid electrolyte material comprising a composite oxide with Li and Bi, having a garnet, perovskite, or LISICON structure, which acts as a sintering aid to promote liquid-phase sintering and enhance ionic conductivity even at temperatures below 800°C, with a preferred composition and structure that includes specific elements and molar ratios to optimize sintering and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-temperature firing (900-1150°C) is used to produce cubic garnet-type solid electrolyte, then the material achieves the required density and structure, but Li elements disappear during firing resulting in reduced ionic conductivity
Solution Approach 1:
The invention changes the firing temperature parameter from conventional high temperature (900-1150°C) to low temperature (800°C or lower). This parameter change is enabled by substituting La with Bi in the cubic garnet structure, which allows the material to achieve adequate density and crystallization at lower temperatures, thereby preventing Li loss and maintaining high ionic conductivity.
Solution Approach 2:
The invention uses a composite oxide containing Li and Bi as a sintering aid combined with the cubic garnet-type solid electrolyte material. This composite approach enables liquid-phase sintering at low temperatures, achieving high density without requiring high-temperature firing that would cause Li evaporation and reduce ionic conductivity.
2Reliability
If low-temperature firing (800°C or lower) is used to prevent Li loss, then ionic conductivity is maintained, but achieving high density and proper crystallization becomes difficult
Solution Approach 1:
The invention modifies the chemical composition parameter by substituting La with Bi and adding Li-Bi composite oxide. This composition change lowers the melting point and enables liquid-phase sintering at temperatures of 800°C or lower, allowing the material to achieve both high density and proper crystallization at temperatures that prevent Li loss.
Solution Approach 2:
The invention utilizes liquid-phase sintering, where the Li-Bi composite oxide forms a liquid phase at low temperatures that facilitates densification. This phase transition approach allows achieving high density at low firing temperatures (800°C or lower) without requiring conventional high-temperature solid-state sintering.
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 solid electrolyte material achieves high ionic conductivity and relative density at low temperatures, improving the performance and reliability of all solid state batteries by maintaining ionic conductivity and preventing side reactions during low-temperature firing.
Implementation Method 1
acts as a sintering aid to promote liquid-phase sintering and enhance ionic conductivity even at temperatures below 800°C
Data Source
AI summary
A solid electrolyte material that includes a composite oxide containing Li and Bi, and at least one solid electrolyte having a garnet structure, a perovskite structure, and a LISICON structure.