Physically Cross-Linked Gel Electrolyte for Thermal Stability
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Solution Overview
Problem
Conventional homopolymer-based gel electrolytes in lithium-ion batteries suffer from thermodynamic and mechanical property declines at elevated temperatures, due to viscosity reduction and solvent-induced dissolution of the homopolymer host, leading to performance issues.
Innovation Solution
A physically cross-linked gel electrolyte using a block co-polymer host with poly(alkylene oxide) and physically cross-linkable units, such as polyamide or poly(terephthalate)ester, which provides enhanced electrochemical, thermodynamic, and mechanical stability through hydrogen bonding and crystallite formation, allowing for robust lithium ion conductivity and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a homopolymer-based gel electrolyte is used, then the gel electrolyte can conduct lithium ions, but the thermodynamic and mechanical properties decline at elevated temperatures
Solution Approach 1:
The patent uses a block copolymer host composed of poly(alkylene oxide) blocks and physically cross-linkable blocks, creating a composite material structure where the poly(alkylene oxide) blocks provide lithium ion conductivity while the physically cross-linkable blocks form hard domains that maintain structural integrity at elevated temperatures, resolving the contradiction between ion conductivity and thermal stability
Solution Approach 2:
The block copolymer structure creates local soft domains (poly(alkylene oxide) blocks) for electrolyte absorption and ion transport, and local hard domains (physically cross-linked regions) for structural stability, allowing different regions to perform different functions that collectively resolve the temperature-stability contradiction
2Device complexity
If a homopolymer host is used, then the gel electrolyte structure is simple, but the solvent dissolves the homopolymer host at cell operating temperatures
Solution Approach 1:
The block copolymer combines poly(alkylene oxide) blocks with physically cross-linkable blocks to create a composite structure where the cross-linked hard domains resist solvent dissolution while the soft domains maintain electrolyte compatibility, solving the contradiction between structural simplicity and compositional stability
Solution Approach 2:
The invention extracts the cross-linking function from the main polymer chain by using physically cross-linkable blocks that form separate hard domains, allowing the poly(alkylene oxide) blocks to maintain their ion-conducting properties while the cross-linked regions provide dissolution resistance
3Reliability
If physical cross-links are introduced to improve stability, then electrochemical and mechanical properties are enhanced, but manufacture into desired forms becomes difficult
Solution Approach 1:
The patent uses physically cross-linkable blocks that can be manipulated through temperature and solvent parameters during manufacturing, allowing the material to be processed in a uncross-linked or partially cross-linked state and then finalized through controlled physical cross-linking, thereby maintaining ease of manufacture while achieving enhanced 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 block co-polymer host's soft and hard domains enhance liquid electrolyte absorption and heat resistance, maintaining operational stability across a wide temperature range and reducing solvent-induced dissolvability, thus improving the overall performance and durability of the gel electrolyte in lithium-ion batteries.
Implementation Method 1
a compatible liquid electrolyte—which can transport lithium ions—absorbed into the block co-polymer host
Implementation Method 2
Non-chemically bonded molecular interactions of this kind include hydrogen bonding and crystallite formation
Implementation Method 3
Non-chemically bonded molecular interactions of this kind include hydrogen bonding and crystallite formation
Implementation Method 4
a compatible liquid electrolyte—which can transport lithium ions
Data Source
AI summary
An electrochemical battery cell of a lithium ion battery has a physically cross-linked gel electrolyte situated between a negative electrode and a positive electrode. The gel electrolyte includes a block co-polymer host and a liquid electrolyte, which can transport lithium ions, absorbed into the block co-polymer host. The block co-polymer host includes poly(alkylene oxide) block units and physically cross-linkable block units. A few preferred physically cross-linkable block units that may be employed include polyamide block units and poly(terephthalate)ester block units.