Lithium Ion Conductive Solid Electrolyte Manufacturing
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Solution Overview
Problem
Current lithium-ion secondary batteries using inorganic solid electrolytes have limited lithium ion conductivity at room temperature, which restricts their application to small-size devices, and conventional ion-exchange methods do not adequately enhance conductivity for broader use.
Innovation Solution
A method involving a crystalline material with a mica or NASICON type crystal structure, subjected to an ion-exchange process in molten salt containing lithium ions, where the material is heat-treated and optionally thinned to improve ionic conductivity, resulting in a lithium ion conductive solid electrolyte with enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic solid electrolytes are used to replace liquid electrolytes, then safety and voltage stability are improved, but lithium ion conductivity at room temperature deteriorates
Solution Approach 1:
The patent applies parameter changes by controlling the water content of molten salt during ion-exchange process (0.1-5 mass%) and optimizing ion-exchange temperature (30-150°C) and time (1-48 hours) to achieve the desired lithium ion conductivity while maintaining safety benefits of solid electrolytes
Solution Approach 2:
The patent creates a composite structure by forming a gradient concentration profile of lithium ions within the glass electrolyte through controlled ion-exchange process, where the concentration of lithium ions varies from the surface to the interior, combining benefits of both high conductivity and structural stability
2Object-generated harmful factors
If conventional ion-exchange process is applied to glass electrolytes, then lithium ion conductivity is improved, but the improvement is not sufficient for broader battery applications
Solution Approach 1:
The patent significantly improves upon conventional ion-exchange by optimizing water content parameter (0.1-5 mass%) in molten salt, which enables achieving lithium ion conductivity of 10^-5 to 10^-3 S/cm at room temperature, sufficient for broader battery applications beyond small devices
Solution Approach 2:
The patent uses molten salt as an intermediary medium for ion-exchange process, where the controlled presence of water in the molten salt facilitates enhanced lithium ion diffusion into the glass electrolyte structure, achieving superior conductivity compared to conventional dry ion-exchange methods
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 method significantly increases lithium ion conductivity by one to several orders of magnitude, enabling the use of the solid electrolyte in larger lithium-ion secondary batteries with improved stability and safety compared to conventional liquid electrolytes.
Implementation Method 1
a method involving a crystalline material with a mica or NASICON type crystal structure, subjected to an ion-exchange process in molten salt containing lithium ions
Implementation Method 2
the material is heat-treated and optionally thinned to improve ionic conductivity
Data Source
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AI summary
The present invention relates to a method of manufacturing a lithium ion conductive solid electrolyte that is used for a lithium-ion secondary battery or the like and a lithium-ion secondary battery including such a lithium ion conductive solid electrolyte. Although a method is proposed in which glass including monovalent ions whose ionic radii are larger than those of lithium ions is performed with an ion-exchange process in lithium ions contained in molten salt is proposed conventionally, the improved effect of the lithium ion conductivity was not enough. A method of manufacturing a lithium ion conductive solid electrolyte includes (a) a step of preparing an object to be processed including a crystalline material, that includes alkali metal other than lithium and whose ionic conductivity at room temperature is greater than or equal to 1 × 10-13 S/cm; and (b) a step of performing an ion-exchange process on the object to be processed in molten salt including lithium ions.