Modified Sulfide Solid Electrolyte for Low H2S and Stable Ionic Conductivity
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Solution Overview
Problem
Conventional sulfide solid electrolytes used in lithium-ion batteries suffer from reduced ionic conductivity and insufficient suppression of hydrogen sulfide (H2S) gas generation when exposed to moisture, leading to safety and performance issues over medium- and long-term use.
Innovation Solution
A modified sulfide solid electrolyte is produced by mixing sulfide solid electrolyte with lithium sulfide (Li2S) in specific proportions, enhancing ionic conductivity and reducing H2S gas generation through a controlled Li2S content and composition, including (1-X-Y)(0.75Li2S/0.25P2S5)/XLiBr/YLi, where X and Y represent the proportion of LiBr and LiI, to optimize conductivity and gas suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If Li2S is completely eliminated to reduce H2S gas generation, then H2S suppression improves, but ionic conductivity reduces
Solution Approach 1:
The patent extracts and removes residual Li2S from the solid electrolyte through controlled reaction with P2S5, converting it into Li3PS4. This extraction process eliminates the harmful H2S gas generation source while preserving the necessary ionic conductivity by maintaining the Li3PS4 phase structure.
Solution Approach 2:
The patent changes the chemical composition parameters by controlling the molar ratio of Li2S to P2S5 and adjusting the sulfur content. By precisely controlling these parameters, the solid electrolyte achieves a state where H2S generation is suppressed (through complete Li2S consumption) while ionic conductivity is maintained (through optimized Li3PS4 structure).
2Reliability
If Li2S content is increased to maintain ionic conductivity, then ionic conductivity improves, but H2S gas generation increases
Solution Approach 1:
The patent converts the potentially harmful residual Li2S into beneficial Li3PS4 structure by controlling the reaction conditions. The Li2S that would normally generate H2S gas is instead transformed into the active ionic conduction phase, turning a harmful component into a beneficial one that simultaneously provides conductivity and suppresses gas generation.
Solution Approach 2:
The patent creates a composite solid electrolyte system comprising Li3PS4 with controlled residual Li2S content. This composite structure leverages the high ionic conductivity of Li3PS4 while using the controlled Li2S content to maintain structural integrity, achieving both high conductivity and H2S suppression through the synergistic combination of phases.
3Ease of manufacture
If conventional solid electrolyte is used without modification, then manufacturing is simple, but H2S gas accumulates over medium- and long-term use
Solution Approach 1:
The patent applies preliminary action by pre-treating the solid electrolyte during manufacturing to control the Li2S content and reaction state. By adjusting the sintering conditions and composition ratios during production, the electrolyte is prepared in advance to minimize H2S generation potential, eliminating the need for complex post-manufacturing treatments while ensuring long-term safety.
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 modified sulfide solid electrolyte maintains high ionic conductivity while significantly reducing cumulative H2S gas generation over extended periods, even when exposed to moisture, thereby enhancing the safety and performance of lithium-ion batteries.
Implementation Method 1
easily reacts with water (hereinafter, also including moisture) or oxygen, and generates a hydrogen sulfide (H2S) gas especially by coming in contact with water
Implementation Method 2
This sulfide solid electrolyte has a high lithium ionic conductivity (hereinafter, also simply referred to as ionic conductivity)
Data Source
AI summary
An object of the present invention is to provide a method of producing a modified sulfide solid electrolyte in which ionic conductivity reduction is suppressed, and a generation amount of a hydrogen sulfide gas is reduced even if a sulfide solid electrolyte comes in contact with moisture and hydrogen sulfide is generated, and the modified sulfide solid electrolyte, and an electrode combined material and a lithium ion battery using the same. The modified sulfide solid electrolyte producing method according to the present invention includes mixing the sulfide solid electrolyte with Li2S, in which (100-α) parts by mass of the sulfide solid electrolyte is used per a parts by mass of Li2S (a represents a number of 0.3 to 15.0).