Zinc-Substituted Lithium-Deficient Solid Electrolytes for Low H2S Evolution
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Solution Overview
Problem
Conventional lithium secondary batteries using liquid electrolytes face safety issues such as leakage and fire risk, while existing solid electrolytes, particularly sulfide-based ones, have limitations in ionic conductivity and moisture-induced H2S gas evolution.
Innovation Solution
Development of metal-substituted lithium-deficient solid electrolytes with specific compositions, including zinc substitution, to enhance ionic conductivity and reduce H2S gas evolution upon moisture contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If sulfide-based solid electrolytes are used to achieve higher lithium ionic conductivity, then ionic conductivity is improved, but H2S gas evolution upon contact with moisture increases
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of the solid electrolyte through metal substitution (replacing Li with divalent metals like Zn, Cu, or Ni) and aliovalent doping. This changes the stoichiometric ratios and creates lithium vacancies, which simultaneously improves ionic conductivity through enhanced Li+ diffusion pathways and reduces H2S evolution by stabilizing the sulfide structure against moisture degradation.
Solution Approach 2:
The patent creates composite solid electrolyte materials by combining multiple elements (Li, divalent metal, P, S, and halogen) in specific ratios defined by the formula Li6-2xMxPS5X. This composite approach integrates the beneficial properties of different elements: the divalent metals provide structural stability and reduce H2S evolution, while the lithium vacancies enhance ionic conductivity, achieving both goals simultaneously.
2Use of energy by moving object
If metal substitution is applied to improve ionic conductivity, then lithium diffusion is enhanced, but structural stability may be compromised
Solution Approach 1:
The patent applies local quality by introducing metal substitutions at specific lattice positions (replacing Li at the 4a site) while maintaining the overall argyrodite crystal structure. The divalent metal atoms occupy specific sites and create localized lithium vacancies that enhance Li+ diffusion pathways without disrupting the global structural framework, thus improving diffusion while preserving structural stability.
Solution Approach 2:
The patent carefully controls the substitution parameter x within the range 0.01 ≤ x ≤ 0.30 to optimize the balance between ionic conductivity and structural stability. This parameter change creates an optimal concentration of lithium vacancies for enhanced diffusion while preventing excessive substitution that would compromise the crystal structure's integrity.
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 new electrolytes exhibit increased ionic conductivity and improved moisture stability, making them safer and more suitable for commercial battery applications.
Implementation Method 1
sulfide based solid electrolytes having an argyrodite-type crystal structure
Data Source
AI summary
This invention relates to a lithium-deficient solid electrolyte substituted with zinc. The present inventors have surprisingly found that these zinc-substituted lithium-deficient solid electrolyte display an increased ionic conductivity. Moreover, these solid electrolyte compositions according to the invention display a reduced H2S gas evolution upon contact with moisture.