Li-Deficient Solid Electrolyte for Stable Battery Conductivity
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Solution Overview
Problem
Existing solid electrolyte materials for all-solid-state batteries face challenges such as phase transitions within the operating temperature range, leading to instability in ionic conductivity and potential safety hazards due to hydrogen sulfide generation.
Innovation Solution
A solid electrolyte material with a Li-deficient crystal phase, specifically represented by the composition Li3−3δY1+δCl6, which maintains high lithium ion conductivity without phase transitions and avoids hydrogen sulfide generation, utilizing a mechanochemical milling method and specific firing conditions to achieve a stable structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solid electrolyte materials are used, then ionic conductivity can be achieved, but phase transitions occur within the operating temperature range causing instability
Solution Approach 1:
The invention changes the compositional parameters by creating a Li-deficient crystal phase with specific composition ratios (Li:Y:Cl in ranges of 2.7-2.9:1.0-1.1:5.8-6.2). This compositional modification shifts the phase transition temperature outside the battery operating range, ensuring phase stability and reliable ionic conductivity without the phase transitions that plague conventional solid electrolyte materials.
2Reliability
If sulfide solid electrolytes are used, then high ionic conductivity is achieved, but hydrogen sulfide generation creates safety hazards
Solution Approach 1:
The invention eliminates the harmful sulfur component entirely by using a chloride-based solid electrolyte system (Li-Y-Cl) instead of sulfide-based materials. This compositional substitution removes the source of hydrogen sulfide generation while maintaining high ionic conductivity through the Li-deficient crystal phase structure, converting a potentially harmful material class into a safe alternative.
3Reliability
If stoichiometric composition Li3YCl6 is used, then crystal structure stability is achieved, but lithium ion conductivity is insufficient
Solution Approach 1:
The invention applies local quality by creating a Li-deficient crystal phase where lithium content is intentionally reduced in specific regions of the crystal structure. This local compositional variation (Li deficiency) creates vacancies that enhance lithium ion mobility and conductivity, while the overall crystal structure remains stable through controlled deviation from stoichiometric composition.
Data Source
AI summary
A solid electrolyte material includes a first crystal phase. The first crystal phase has a composition that is deficient in Li as compared with a composition represented by the following composition formula (1).Li3Y1Cl6 formula (1)