Sulfur-Substituted Halide Solid Electrolyte for Stable Li-Ion Conduction
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Solution Overview
Problem
Conventional lithium secondary batteries face issues with low thermal stability, ignition, leakage, and insufficient lithium ion conductivity due to the use of liquid electrolytes, while existing halide solid electrolytes do not exhibit sufficient ionic conductivity and stability, especially when exposed to moisture and oxygen.
Innovation Solution
A halide solid electrolyte represented by Li (6-4a+b) M a X 6-b S b, where M is a tetravalent transition metal, X is a halogen, and a part of the halogen element is substituted and doped with sulfur, enhancing lithium ion conductivity and structural stability through controlled sulfur substitution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid electrolyte is used in lithium secondary batteries, then ionic conductivity is achieved, but thermal stability and safety deteriorate due to low thermal stability, ignition, and leakage
Solution Approach 1:
The patent changes the physical state parameter of the electrolyte from liquid to solid, and modifies the chemical composition by substituting halogen elements with sulfur in the halide solid electrolyte formula Li(6-4a+b)MaX6-bSb. This parameter transformation achieves both high ionic conductivity (comparable to liquid electrolytes) and improved thermal stability, resolving the contradiction between safety and ionic conductivity
Solution Approach 2:
The patent develops composite solid electrolyte materials combining halide base structures with sulfur substitution. The composite nature of Li(6-4a+b)MaX6-bSb integrates the stability of halide frameworks with the high ionic conductivity contributions from sulfur doping, achieving both safety and performance requirements
2Ease of operation
If sulfide-based solid electrolyte is used, then flexibility and contact properties improve, but stability deteriorates due to low stability when exposed to moisture and oxygen
Solution Approach 1:
The patent uses halide compounds as intermediary materials that bridge the gap between sulfide-based flexibility and oxide-based stability. The halide solid electrolyte Li(6-4a+b)MaX6-bSb acts as a mediator, incorporating sulfur to achieve flexibility and contact properties similar to sulfides, while the halide framework provides enhanced stability against moisture and oxygen
Solution Approach 2:
The patent applies local quality by selectively substituting only part of the halogen elements with sulfur in the crystal structure (indicated by the parameter b in Li(6-4a+b)MaX6-bSb). This partial substitution locally introduces flexibility and contact properties where needed, while maintaining the stable halide framework in other regions, thus achieving both flexibility and stability
3Stability of the object's composition
If oxide-based solid electrolyte is used, then stability improves, but ionic conductivity and contact properties deteriorate due to insufficient ionic conductivity
Solution Approach 1:
The patent changes the chemical composition parameters by introducing sulfur substitution in halide structures, which fundamentally alters the ionic conduction mechanism. The Li(6-4a+b)MaX6-bSb composition achieves high lithium ion conductivity through sulfur-induced structural modifications while maintaining the stability characteristic of oxide-based materials
4Quantity of substance
If halide solid electrolyte with sulfur substitution is used, then ionic conductivity improves, but manufacturing complexity increases due to controlled sulfur substitution requirements
Solution Approach 1:
The patent defines specific parameter ranges for sulfur substitution (controlled by parameter b in the formula Li(6-4a+b)MaX6-bSb) that optimize ionic conductivity while maintaining manufacturing feasibility. By establishing clear compositional windows, the patent balances performance improvement with manufacturing complexity, making the material both high-performing and producible
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 exhibits improved ionic conductivity, flexibility, and stability, enabling safer and high-energy density secondary batteries by ensuring excellent contact properties between the electrolyte and active material particles.
Implementation Method 1
a part of the halogen element is substituted and doped with sulfur, enhancing lithium ion conductivity and structural stability through controlled sulfur substitution
Implementation Method 2
reacting a mixture of lithium halide, a group 4 transition metal M halide, and lithium sulfide under the application of mechanical force
Data Source
Figure 1~2
Figure 3a
Figure 3b
AI summary
The present disclosure relates to a halide solid electrolyte that exhibits a more improved ionic conductivity, excellent stability and flexibility, and the like, a method for producing the same, and a secondary battery comprising the same. The halide solid electrolyte may be represented by the Formula: Li(6-4a+b)MaX6-bSb.