Thiol-Aromatic Polymers for Lithium Battery Protective Layers
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Solution Overview
Problem
Lithium-based electrochemical cells face challenges such as lithium reactivity, dendrite formation, electrolyte compatibility, and safety issues due to the susceptibility of polymeric materials to nucleophilic attack by polysulfides, leading to reduced cycle life and conductivity.
Innovation Solution
Development of polymers formed by reacting monomers with two thiol groups and monomers containing vinyl or alkynyl groups, which are stable to nucleophilic attack and can be rapidly formed on lithium surfaces, providing enhanced compatibility and mechanical integrity as protective layers in electrochemical cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymeric materials formed from polymerization of acrylate monomers are used on lithium surface, then protective layer formation is achieved, but the polymers are susceptible to nucleophilic attack by polysulfides leading to reduced conductivity and cycle life
Solution Approach 1:
The patent changes the chemical composition parameters of the polymer by incorporating thiol groups and aromatic rings, which fundamentally alters the polymer's resistance to nucleophilic attack by polysulfides. This compositional parameter change resolves the contradiction between maintaining protective layer function and achieving stability against chemical degradation.
Solution Approach 2:
The patent creates a composite polymer structure combining thiol groups, aromatic rings, and cross-linking bridges to form a material that simultaneously provides protection against polysulfide attack while maintaining ionic conductivity. The composite nature of this polymer resolves the contradiction by integrating multiple functional components that address both reliability and stability requirements.
2Strength
If polymers with high cross-linking density are used to improve mechanical integrity, then structural strength increases, but ionic conductivity decreases
Solution Approach 1:
The patent optimizes the cross-linking density parameter within a specific range (0.1 to 5.0 mmol/g) to balance mechanical strength and ionic conductivity. By precisely controlling this parameter, the patent resolves the contradiction between structural integrity and ion transport capability.
Solution Approach 2:
The patent introduces localized aromatic ring structures and thiol groups at specific positions within the polymer matrix, creating regions of enhanced stability without uniformly increasing cross-linking density throughout the entire structure. This local quality approach maintains overall ionic conductivity while providing targeted mechanical reinforcement.
3Object-affected harmful factors
If polymerization is performed to form protective layer on lithium surface, then protection against dendrites is achieved, but adverse reactions with electrolyte components occur
Solution Approach 1:
The patent converts the potential harm of polysulfide attack into a benefit by incorporating thiol groups that specifically bind to polysulfides, transforming the harmful nucleophilic species into stabilized complexes. This approach resolves the contradiction by turning the adverse reaction mechanism into a protective function.
Solution Approach 2:
The patent introduces thiol groups as intermediary structures that mediate between the lithium surface and polysulfides. These thiol groups act as sacrificial intermediaries that preferentially react with polysulfides, protecting the underlying lithium and maintaining protective layer integrity without generating harmful byproducts.
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 polymers exhibit improved stability and ionic conductivity, reducing dendrite formation and enhancing the cycle life and safety of lithium-based electrochemical cells by preventing adverse reactions with polysulfides and electrolytes.
Implementation Method 1
the polymers are stable to nucleophilic attack by species present within the electrochemical cell, such as polysulfides generated during sulfur discharge
Implementation Method 2
The polymers may exhibit enhanced compatibility with battery environments... exhibiting improved stability and ionic conductivity
Data Source
Figure 1A~1D
Figure 2A~2C
Figure 3~4
AI summary
Polymers for use as protective layers and other components in electrochemical cells are provided. In some embodiments, the electrochemical cell is a lithium-based electrochemical cell.