LiBH4 Sulfide Solid Electrolyte for High Ionic Conductivity
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Solution Overview
Problem
Current sulfide solid electrolytes for all-solid-state batteries have limited ionic conductivity, with existing methods producing materials with conductivities of at most 2.0 mS/cm, which hinders battery performance.
Innovation Solution
A sulfide solid electrolyte with a composition of (100−x)[yLi2S·(1−y)P2S5]·xLiBH4, where 50<x<75 and 0.72≤y≤0.78, is produced using a mechanical milling process that applies a gravity of at least 6 G, followed by a heat treatment at 190° C or less, enhancing ionic conductivity to 5.0 mS/cm or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional heat treatment methods are used to produce sulfide solid electrolyte, then the production process is simple, but the ionic conductivity is limited to at most 2.0 mS/cm
Solution Approach 1:
The patent changes the production parameters from conventional heat treatment to mechanical milling with controlled gravity (6G or higher), followed by low-temperature heat treatment (190°C or lower). This parameter change transforms the production method to achieve ionic conductivity of 5.0 mS/cm or higher, resolving the contradiction between simplicity and performance.
Solution Approach 2:
The patent uses a composite material system with specific composition ratios: Li2S (40-70 mol%), P2S5 (10-30 mol%), and LiBH4 (20-50 mol%). This composite approach enables achieving high ionic conductivity (5.0 mS/cm or higher) that cannot be obtained with conventional single-phase materials, resolving the performance limitation.
2Reliability
If mechanical milling with high gravity is applied to improve ionic conductivity, then the ionic conductivity increases to 5.0 mS/cm or more, but the production process becomes more complex
Solution Approach 1:
The patent specifies precise parameter ranges for mechanical milling (gravity ≥6G, rotation-to-revolution ratio, specific duration) and heat treatment (temperature ≤190°C, time ≥1 hour). These controlled parameter changes achieve high ionic conductivity while providing clear manufacturing guidelines, balancing performance improvement with manufacturing feasibility.
3Reliability
If the composition ratio of Li2S, P2S5, and LiBH4 is optimized to enhance ionic conductivity, then the ionic conductivity improves, but the manufacturing precision requirements increase
Solution Approach 1:
The patent defines specific composition ranges: Li2S (40-70 mol%), P2S5 (10-30 mol%), and LiBH4 (20-50 mol%). These parameter specifications achieve ionic conductivity of 5.0 mS/cm or higher while providing clear manufacturing targets, balancing performance optimization with controllable manufacturing precision.
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 resulting sulfide solid electrolyte exhibits significantly improved ionic conductivity, up to 8.0 mS/cm, and maintains good crystallinity, enhancing battery performance and discharge capacity retention.
Implementation Method 1
a first mechanical milling step of mechanically milling a mixture containing Li2S and P2S5 to obtain a first sulfide glass; and a second mechanical milling step of adding LiBH4 to the first sulfide glass and mechanically milling a mixture of the first sulfide glass and LiBH4 to obtain a second sulfide glass
Implementation Method 2
a heat treatment step of heat treating the sulfide glass. The temperature of the heat treatment may be 190° C. or less
Data Source
AI summary
A sulfide solid electrolyte for use in an all-solid-state battery has a composition represented by (100−x) [yLi2S·(1−y)P2S5]·xLiBH4. In the formula, x is a value satisfying 50<x<75, and y is a value satisfying 0.72≤y≤0.78. The sulfide solid electrolyte has an ionic conductivity of 5.0 mS/cm or more at 25° C.