Sulfide solid electrolyte for solid-state batteries and method for production
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Solution Overview
Problem
Existing sulfide solid electrolytes for solid-state batteries suffer from rapid short-circuiting and low power density due to phosphorous degradation and air instability, despite improvements in ionic conductivity and stability.
Innovation Solution
A sulfide solid electrolyte with a composition of Li6+x Mx Sb1−y S5−z R, where x, y, and z range from 0 to 0.7, and M includes tungsten, with iodine as the radical R, enhances ionic conductivity and stability, preventing short circuits and poisonous gas formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phosphorous is used in the solid electrolyte composition, then ionic conductivity is improved, but air stability deteriorates due to oxygen binding and degradation
Solution Approach 1:
The patent changes the chemical composition parameters by replacing phosphorous with antimony and adjusting the stoichiometric ratios of Li, Sb, S, and halogen elements. This compositional parameter change achieves both high ionic conductivity (through optimized Li content with x=0.05-0.7) and air stability (through antimony's resistance to oxygen binding), resolving the contradiction between conductivity and stability.
Solution Approach 2:
The patent creates a composite solid electrolyte material combining antimony sulfide with lithium halide (Cl, Br, or I) in a specific composite structure. This composite approach allows the material to simultaneously exhibit the air stability of antimony-based compounds and the ionic conductivity enhanced by lithium halide components, resolving the contradiction between stability and conductivity.
2Power
If iodine is used as the halogen in the solid electrolyte, then power density is improved, but chemical stability deteriorates
Solution Approach 1:
The patent optimizes the iodine content parameter within a specific range (z=0.05-0.7) rather than using stoichiometric amounts. This parameter optimization achieves high power density through sufficient iodine for lithium diffusion while preventing excessive iodine from causing decomposition or short circuits, thus resolving the contradiction between power and stability.
Solution Approach 2:
The patent creates local regions with different iodine concentrations within the solid electrolyte structure. The composition Li6+xSb1−yS5−zR allows for spatial variation in halogen content, with iodine-rich regions providing high ionic conductivity for power density while iodine-poor regions maintaining chemical stability, resolving the local contradiction between power and stability.
3Power
If the solid electrolyte composition is optimized for high power, then power density increases, but short circuit resistance deteriorates
Solution Approach 1:
The patent optimizes multiple composition parameters simultaneously (x, y, z values) to achieve a balanced composition that provides both high power density and short circuit resistance. The specific formula Li6+xSb1−yS5−zR with controlled stoichiometry ensures sufficient ionic conductivity for power while preventing composition degradation that would lead to short circuits, resolving the contradiction between power and reliability.
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 electrolyte achieves higher power and power density with improved safety by stabilizing against air, moisture, and lithium, and reduces activation energy for lithium diffusion.
Implementation Method 1
reduces activation energy for lithium diffusion
Data Source
AI summary
A solid electrolyte for solid-state batteries comprises a phosphorous-free solid electrolyte having a cubic argyrodite structure. The solid electrolyte has a composition according to the molecular formula: Li6+xMxSb1−yS5−zR, where x=0 to 0.7; y=0 to 0.7 and z=0 to 0.7, wherein the (semi-) metal comprises M=Si, Sn, W and the halogen comprises R=I1, Cl1, Brz, Br1 and further wherein, in a case where R=I1, M=W and x>0. Furthermore, a production method is described.