Core-Shell Solid Electrolyte for Higher-Conductivity Batteries
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Solution Overview
Problem
Conventional oxide-based solid electrolytes for secondary batteries have low ion conductivities, limiting the output density and performance of secondary batteries, and existing pyrochlore solid electrolytes require further improvements in ion conductivity to enhance battery performance.
Innovation Solution
A solid electrolyte with a core phase having a pyrochlore structure and a shell phase, where the shell phase is composed of materials with a lower melting point and different chemical composition than the core, improving relative density and contact area, thereby enhancing ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional oxide-based solid electrolytes are used, then safety is improved by eliminating organic solvents, but ion conductivity remains low limiting battery performance
Solution Approach 1:
The patent creates a composite solid electrolyte consisting of a core phase (pyrochlore solid electrolyte particles) and a shell phase (glassy matrix material). This composite structure combines the high ion conductivity of pyrochlore materials with the beneficial properties of glassy matrices, achieving both improved safety and enhanced ion conductivity beyond what conventional oxide-based electrolytes can provide.
Solution Approach 2:
The patent modifies the chemical composition parameters of the glassy matrix material in the shell phase, specifically controlling the ratio of network formers (SiO2, B2O3, P2O5) and network modifiers (Li2O, Na2O, K2O, CaO, Al2O3). By optimizing these compositional parameters, the patent achieves a glassy matrix with appropriate melting point and ion conductivity to enhance overall electrolyte performance.
2Productivity
If pyrochlore solid electrolyte particles are used to improve ion conductivity, then element diffusion occurs at interfaces requiring further improvements
Solution Approach 1:
The patent introduces a glassy matrix material as an intermediary substance between pyrochlore solid electrolyte particles. This glassy matrix acts as a mediator that fills the spaces between particles and forms a continuous phase, preventing direct contact and element diffusion between pyrochlore particles while maintaining ion conductivity pathways through the glassy phase itself.
Solution Approach 2:
The glassy matrix forms a flexible, amorphous shell phase that conforms to the pyrochlore particle surfaces and fills interparticle spaces. This flexible glassy shell provides a stable interface that prevents element diffusion while allowing ionic transport, overcoming the rigidity and interface instability issues of conventional crystalline oxide electrolytes.
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 composite solid electrolyte design significantly improves ion conductivity and relative density, leading to enhanced performance in secondary batteries by restricting element diffusion and reducing interface resistance.
Implementation Method 1
A constituent material of the shell phase includes a material having a chemical composition including Li and different from a chemical composition of the pyrochlore solid electrolyte, and having a melting point lower than a melting point of the pyrochlore solid electrolyte
Data Source
AI summary
A solid electrolyte for a secondary battery includes a core phase having a particle shape and a shell phase covering at least a part of the core phase. The shell phase consists of one or more phases. A constituent material of the core phase includes a pyrochlore solid electrolyte represented by a composition formula of Aa2−αAb(1+α)/3B2O7−βXβ, where Aa is an alkali metal, Ab is a lanthanoid, B is a cationic metal, and X is an anion that is substitutable with O. A constituent material of the shell phase includes a material having a chemical composition including Li and different from a chemical composition of the pyrochlore solid electrolyte, and having a melting point lower than a melting point of the pyrochlore solid electrolyte.