Sulfide Solid Electrolyte Composition for Oxidation and Reduction Resistance
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Solution Overview
Problem
Conventional sulfide-based solid electrolytes face issues with reduction resistance when using lithium metal as the negative electrode and oxidation resistance with high-potential active materials, leading to increased resistance due to the formation of resistive layers or oxidized films.
Innovation Solution
A sulfide-based solid electrolyte is developed with a chemical bond between Li2S and P2S5, incorporating LiBH4 at a mole ratio of 1:0.5, which enhances both oxidation and reduction resistance, and is manufactured using a liquid phase method with specific mole ratios and heat treatment to improve conductivity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sulfide-based solid electrolyte is used, then high lithium-ion conductivity is achieved, but reduction resistance to lithium metal deteriorates
Solution Approach 1:
The patent employs a composite solid electrolyte system combining Li2S-P2S5 glass ceramic matrix with LiBH4 additive. This composite structure leverages the high ionic conductivity of the sulfide glass ceramic while LiBH4 forms protective interfacial layers that prevent reduction reactions with lithium metal, thus resolving the contradiction between maintaining conductivity and improving reduction resistance
Solution Approach 2:
LiBH4 acts as an intermediary substance between the sulfide-based solid electrolyte and lithium metal negative electrode. It forms a stable protective interface layer that mediates the interaction, preventing direct contact and reduction reactions between the electrolyte and lithium metal, thereby improving reduction resistance without significantly impacting ionic conductivity
2Reliability
If conventional sulfide-based solid electrolyte is used, then high lithium-ion conductivity is achieved, but oxidation resistance to high-potential active material deteriorates
Solution Approach 1:
The composite structure of Li2S-P2S5 glass ceramic with LiBH4 additive creates a dual-function electrolyte system. The sulfide glass ceramic provides high ionic conductivity while the LiBH4 component forms oxidation-resistant protective films at the interface with high-potential positive electrode materials, thus maintaining conductivity while improving oxidation resistance
Solution Approach 2:
LiBH4 serves as an intermediary protective layer between the sulfide electrolyte and high-potential positive electrode materials. This intermediate layer prevents direct oxidation reactions while allowing lithium-ion transport, thereby resolving the contradiction between maintaining high conductivity and improving oxidation resistance
3Object-affected harmful factors
If LiBH4 is added to improve reduction resistance, then reduction resistance improves, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes the concentration parameter of LiBH4 additive in the solid electrolyte composition. By carefully controlling the amount of LiBH4 added to the Li2S-P2S5 system, the patent achieves effective protection against reduction while maintaining compatibility with existing manufacturing processes, thus improving reduction resistance without excessive increase in manufacturing complexity
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 improved sulfide-based solid electrolyte demonstrates superior oxidation and reduction resistance, enhancing the durability of solid-state secondary batteries, particularly when used with lithium metal as the negative electrode, and allows for increased energy density and reduced production costs.
Implementation Method 1
a chemical bond between Li2S—P2S5 and LiBH4
Implementation Method 2
solid electrolyte used as the conductor of charge transfer medium such as lithium ion
Data Source
AI summary
A sulfide-based solid electrolyte is provided which is superior in oxidation resistance and reduction resistance. A sulfide-based solid electrolyte includes a chemical bond formed between Li2S—P2S5 and LiBH4, in which a mole ratio of the Li2S—P2S5 and the LiBH4 is 1:0.5.