Crosslinked Solid Electrolyte With Balanced Conductivity and Strength
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Solution Overview
Problem
Existing crosslinked solid electrolytes for lithium-ion batteries exhibit low conductivity and mechanical instability due to lack of effective crosslinking agents and optimal molar ratios in thiol-ene reactions.
Innovation Solution
A crosslinkable electrolyte formulation comprising a lithium salt, a hydrocarbon molecule with two thiol functions, an unsaturated hydrocarbon molecule with two C═C double bonds, and a crosslinking agent with at least three C═C double bonds, with a [C═C double bond]/[thiols] molar ratio between 1 and 1.1, is used to enhance conductivity and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If crosslinking is performed without optimal crosslinking agents and molar ratios, then mechanical properties are improved, but ionic conductivity decreases
Solution Approach 1:
The patent optimizes the [C═C double bond]/[thiols] molar ratio parameter to between 1 and 1.1, which resolves the contradiction by finding the precise parameter range where both mechanical crosslinking strength and ionic conductivity are maximized. This parameter optimization ensures sufficient crosslinking for mechanical stability while maintaining adequate ionic pathways for lithium ion transport.
Solution Approach 2:
The patent employs a composite formulation combining multiple components: hydrocarbon molecules with two thiol functions, unsaturated hydrocarbon molecules with two C═C double bonds, and crosslinking agents with at least three C═C double bonds. This composite approach allows simultaneous achievement of mechanical crosslinking and ionic conductivity by distributing functions across different molecular components.
2Stability of the object's composition
If crosslinking density is increased to improve mechanical stability, then network resistance to chemical degradation increases, but ionic conductivity decreases
Solution Approach 1:
The patent precisely controls the crosslinking density through the optimized molar ratio of [C═C double bond]/[thiols] between 1 and 1.1. This parameter control achieves sufficient crosslinking density for chemical stability and mechanical strength while preventing excessive crosslinking that would block ionic pathways and reduce conductivity.
3Productivity
If thiol-ene reaction is performed without optimal molar ratio control, then crosslinking efficiency improves, but mechanical stability and conductivity are compromised
Solution Approach 1:
The patent optimizes the molar ratio parameter to achieve near-stoichiometric balance with a slight excess of C═C double bonds (ratio of 1 to 1.1). This optimization maximizes crosslinking efficiency by ensuring complete reaction of thiol groups while preventing unreacted C═C bonds that would create defects, thereby achieving both high crosslinking efficiency and mechanical stability.
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 formulation achieves significantly higher ionic conductivity (10−5 to 10−7 S/cm) and improved mechanical stability, making it suitable for all-solid-state Li-ion batteries.
Implementation Method 1
The thiol-ene (also alkene hydrothiolation) reaction is a reaction between a thiol and an alkene to form a thioether
Implementation Method 2
In the case of a radical mechanism, it is important to avoid electron-withdrawing substituents (monomers containing an active double bond) in order to be free from the polymerization of unsaturated entities and from uncontrolled side reactions
Implementation Method 3
The hydrothiolation can then be initiated thermally or photochemically
Data Source
AI summary
The present invention relates to a crosslinkable electrolyte formulation comprising at least: —a lithium salt or a mixture of lithium salts—a hydrocarbon molecule comprising two thiol functions—an unsaturated hydrocarbon molecule comprising two C═C double bonds—a crosslinking agent, said crosslinking agent being a molecule carrying at least three C═C double bonds; in which the [C═C double bond]/[thiols] molar ratio is of between 1 and 1.1. The invention also relates to a process for the preparation of a crosslinked solid electrolyte by means of said formulation, and also to the use of said crosslinked solid electrolyte as solid electrolyte of an all-solid-state Li-ion battery or as component of the positive (posolyte or catholyte) or negative (negolyte or anolyte) electrode of an electrochemical system.