Sulfide Solid Electrolyte for Lithium-Ion Battery Safety
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Solution Overview
Problem
Conventional lithium-ion batteries using organic electrolytes pose safety hazards due to flammability and have limitations in ionic conductivity and chemical stability, while existing solid electrolytes like Li10GeP2S12 are costly and unstable with lithium.
Innovation Solution
A solid electrolyte material with the chemical formula Li1+2x−2yMyGa2+xP1−xS6, where M is Sr, Ba, Zn, or Cd, is developed, featuring a monoclinic diamond-like crystal structure and corner-sharing tetrahedral units, optimized for high ionic conductivity and stability, and combined with a binder for improved mechanical strength and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional organic electrolytes are used in lithium-ion batteries, then the batteries can achieve good ionic conductivity, but safety hazards arise due to flammability
Solution Approach 1:
The patent changes the physical state parameter of the electrolyte from liquid (organic electrolyte) to solid (solid electrolyte), specifically using a sulfide-based solid electrolyte with chemical formula Li10-xMxP2-yAlyS12-zOz (where M is Sr, Ba, Zn, or Cd). This parameter change eliminates flammability while maintaining ionic conductivity through the solid-state material's inherent properties
Solution Approach 2:
The patent employs composite material design by combining multiple elements (Li, M, P, A, S, O) in a specific stoichiometric ratio to create a composite solid electrolyte material. This composite structure integrates the advantages of different elements to achieve both safety (non-flammable) and performance (ionic conductivity) requirements
2Reliability
If existing solid electrolytes like Li10GeP2S12 are used, then safety is improved by eliminating flammability, but manufacturing cost increases due to expensive germanium
Solution Approach 1:
The patent replaces expensive germanium (Ge) with cheaper alternative elements (Sr, Ba, Zn, or Cd) in the solid electrolyte composition. These substitute elements are more abundant and cost-effective while maintaining the necessary functional properties of the solid electrolyte, thereby reducing manufacturing cost without compromising safety
Solution Approach 2:
The patent modifies the chemical composition parameters of the solid electrolyte by adjusting the stoichiometric ratios of Li, M, P, A, S, and O elements. This parameter optimization allows the use of cost-effective elements while achieving the desired ionic conductivity and structural stability, thus reducing manufacturing cost
3Reliability
If existing solid electrolytes like Li10GeP2S12 are used, then ionic conductivity is improved, but chemical stability deteriorates due to instability with lithium
Solution Approach 1:
The patent designs a composite solid electrolyte material with multi-element composition (Li, M, P, A, S, O) where each element contributes specific properties. The synergistic combination of these elements in controlled ratios achieves both high ionic conductivity (through optimized crystal structure and ion pathways) and chemical stability (through balanced composition that prevents degradation reactions with lithium)
Solution Approach 2:
The patent optimizes the chemical composition parameters by adjusting the stoichiometric ratios of constituent elements and controlling the oxidation state (z) of oxygen. This parameter tuning enables the solid electrolyte to achieve optimal balance between ionic conductivity and chemical stability, preventing instability issues with lithium
4Reliability
If the structural composition of solid electrolyte is optimized for high ionic conductivity, then ionic conductivity is improved, but chemical stability may deteriorate
Solution Approach 1:
The patent systematically optimizes multiple compositional parameters simultaneously: the type and ratio of M elements (Sr, Ba, Zn, Cd), the stoichiometric coefficients (x, y, z), and the oxidation state. This multi-parameter optimization approach achieves the optimal balance point where both ionic conductivity and chemical stability are maximized, resolving the trade-off between these two properties
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 solid electrolyte achieves enhanced ionic conductivity, stability with lithium, and reduced manufacturing costs, leading to improved safety and performance in electrochemical devices by eliminating the need for expensive germanium and stabilizing lithium ion migration pathways.
Implementation Method 1
the solid electrolyte material has ionic conductivity of about 10−6 S/cm to about 10−4 S/cm and the lithium ion migration barrier of less than about 0.4 eV
Data Source
AI summary
Embodiments of the present application relate to a solid electrolyte and a preparation method thereof, and an electrochemical device and an electronic device comprising the same. The solid electrolyte of the present application includes a solid electrolyte material being represented by the chemical formula of Li1+2x−2yMyGa2+xP1−xS6, where M is selected from the group consisting of Sr, Ba, Zn, Cd and a combination thereof, 0≤x≤0.2 and 0≤y≤0.05. Embodiments of the present application provides a solid electrolyte having good stability with lithium and ionic conductivity by forming the solid electrolyte using lower cost solid electrolyte materials and optimizing the material composition and a crystal structure thereof. At the same time, this also reduces the manufacturing costs of the solid electrolyte, and improves the structural stability of the solid electrolyte.