Pyrochlore Solid Electrolyte for Higher-Conductivity Secondary Batteries
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Solution Overview
Problem
Conventional oxide solid electrolytes with garnet or NASICON structures have low ionic conductivities, making it difficult to enhance the output density of secondary batteries.
Innovation Solution
A solid electrolyte with a pyrochlore structure, specifically an oxide-based electrolyte with a composition formula of Aa2-αAb(1+α)/3B2O7-βXβ, where Aa is an alkali metal, Ab contains a lanthanoid, and X is an anion substitutable with O, is developed to improve ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxide solid electrolytes with garnet or NASICON structures are used, then air stability is improved, but ionic conductivity deteriorates
Solution Approach 1:
The patent applies parameter changes by modifying the crystal structure from garnet or NASICON to pyrochlore structure, and by adjusting compositional parameters (Aa, Ab, B, X elements and their ratios) to achieve both high air stability and high ionic conductivity simultaneously. The pyrochlore structure with specific composition ranges provides stable surface properties while maintaining high ion transport pathways.
Solution Approach 2:
The patent employs composite materials by creating a multi-element doped pyrochlore solid electrolyte containing alkali metals (Aa), lanthanoids (Ab), and other cations (B) with anionic substitutions (X). This composite approach combines the stability benefits of oxide structures with the high conductivity characteristics of doped pyrochlore phases, achieving both air stability and high ionic conductivity.
2Stability of the object's composition
If conventional oxide solid electrolytes are used, then structural stability is improved, but output density deteriorates
Solution Approach 1:
The patent changes the crystal structure parameter from conventional garnet or NASICON to pyrochlore structure, which provides both structural stability and enhanced ionic conductivity. The compositional parameters are optimized within specific ranges to maintain structural stability while maximizing ion transport, thereby increasing output density.
Solution Approach 2:
The patent applies local quality by creating specific local environments within the pyrochlore structure through element substitution at different sites (Aa, Ab, B, X positions). This allows different regions of the crystal structure to provide different functions: some sites maintain structural stability while others facilitate high-speed ion transport, achieving both stability and high output density.
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 pyrochlore structured solid electrolyte exhibits significantly higher ionic conductivity compared to conventional oxide-based electrolytes, enhancing the output density of secondary batteries.
Implementation Method 1
an oxide-based solid electrolyte having a pyrochlore structure and having a composition formula of Aa2-αAb(1+α)/3B2O7-βXβ... capable of improving an ionic conductivity
Data Source
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AI summary
An oxide-based solid electrolyte having a pyrochlore structure and represented by a composition formula Aa2-αAb(1+α)/3B2O7-βXβ is used as a solid electrolyte for a secondary battery. Aa is an alkali metal. Ab contains at least a lanthanide. B is a cationic metal different from Aa and Ab. X is an anion that is substitutable with an O atom constituting the pyrochlore structure.