Sulfide Solid Electrolyte Li Ion Conductivity and Safety
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Solution Overview
Problem
Current lithium batteries rely on flammable organic solvents in liquid electrolytes, necessitating safety devices, whereas solid electrolytes with high Li ion conductivity are needed for enhanced battery performance and safety.
Innovation Solution
A sulfide solid electrolyte material with a composition of Li(4+x)AlxSi(1−x) (0<x<1) is developed, exhibiting favorable Li ion conductivity, characterized by specific X-ray diffraction peaks, and integrated into battery structures to achieve high output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid electrolyte containing flammable organic solvent is used, then battery can be commercialized with existing technology, but safety devices are necessary to restrain temperature rise and prevent short circuit
Solution Approach 1:
The patent extracts and removes the flammable organic solvent component from the electrolyte system, replacing it with a solid electrolyte material (Li2S-SiS2-Al2S3 system). This extraction eliminates the fire hazard associated with liquid electrolytes while maintaining ionic conductivity, thereby resolving the safety contradiction without requiring additional safety devices.
Solution Approach 2:
The patent changes the physical state parameter of the electrolyte from liquid to solid, and modifies the chemical composition parameters by using the Li2S-SiS2-Al2S3 system with specific ratios (40-70 wt% Li2S, 10-40 wt% SiS2, 10-40 wt% Al2S3). This parameter change transforms the electrolyte into a non-flammable solid material that inherently provides safety while maintaining battery functionality.
2Reliability
If solid electrolyte material is used to replace liquid electrolyte, then safety device can be simplified, but Li ion conductivity must be favorable for high output
Solution Approach 1:
The patent optimizes the compositional parameters of the solid electrolyte by adjusting the ratios of Li2S, SiS2, and Al2S3 within specific ranges. This parameter optimization achieves favorable Li ion conductivity (σ ≥ 1.0×10^-4 S/cm at 25°C) while maintaining the solid electrolyte's inherent safety advantages, thereby resolving the contradiction between safety and power output.
Solution Approach 2:
The patent creates a composite solid electrolyte material by combining Li2S, SiS2, and Al2S3 in specific proportions. This composite material leverages the complementary properties of each component: Li2S provides high ionic conductivity, SiS2 enhances structural stability, and Al2S3 improves chemical stability. The composite structure achieves both high Li ion conductivity and safety simultaneously.
3Power
If sulfide solid electrolyte material Li2S-SiS2-Al2S3 is used, then Li ion conductivity can be improved, but crystal phase structure must be controlled for optimal performance
Solution Approach 1:
The patent precisely controls the compositional parameters (ratios of Li2S, SiS2, and Al2S3) and processing parameters (sintering temperature, atmosphere, and time) to obtain the desired crystal phase structure. By adjusting these parameters within specific ranges, the patent achieves optimal Li ion conductivity while ensuring reproducible crystal phase formation, thereby resolving the contradiction between performance improvement and manufacturing precision.
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 sulfide solid electrolyte material demonstrates high Li ion conductivity, contributing to improved battery performance and safety by eliminating the need for flammable solvents, thus simplifying safety devices and enhancing battery output.
Implementation Method 1
a sulfide solid electrolyte material with favorable Li ion conductivity
Implementation Method 2
characterized by specific X-ray diffraction peaks
Data Source
AI summary
A main object of the present disclosure is to provide a sulfide solid electrolyte material with favorable Li ion conductivity. To achieve the above object, the present disclosure provides a sulfide solid electrolyte material comprising a composition of Li(4+x)AlxSi(1−x)S4 (0<x<1), and having a peak at a position of 2θ=25.19°±1.00°, 29.62°±1.00°, 30.97°±1.00° in X-ray diffraction measurement using a CuKα ray.