Siloxane Crosslinked Separator for Lithium Battery Thermal Stability
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Solution Overview
Problem
Rechargeable lithium batteries face challenges in achieving high heat resistance, oxidation resistance, and electrolyte solution wettability, which are crucial for maintaining cell performance and safety, especially during high voltage operations and thermal stability.
Innovation Solution
A separator for rechargeable lithium batteries is developed, featuring a substrate with a heat-resistant porous layer containing a crosslinked binder made from a siloxane resin with a T-shaped unit and a filler, which provides improved heat resistance and oxidation resistance while ensuring excellent electrolyte solution wettability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional binder is used in the separator, then the manufacturing process is simple, but the heat resistance and oxidation resistance are insufficient
Solution Approach 1:
The patent uses a composite binder system combining siloxane resin with crosslinkable functional groups and reactive diluents. The siloxane resin provides heat resistance while the crosslinkable groups form a three-dimensional network structure through reaction with reactive diluents, creating a composite material that achieves both high heat resistance and oxidation resistance without excessive structural complexity
Solution Approach 2:
The patent modifies the binder properties by changing the chemical structure parameters of the siloxane resin, specifically incorporating crosslinkable functional groups (epoxy, hydroxyl, carboxyl, amino groups) and controlling the molecular weight and functional group content to achieve optimal heat resistance and oxidation resistance while maintaining processability
2Reliability
If the separator structure is simplified, then the manufacturing is easier, but the thermal stability and short-circuit prevention are compromised
Solution Approach 1:
The patent applies a heat-resistant porous layer to the separator surface before final assembly. This preliminary action of coating the substrate with the crosslinked siloxane binder and inorganic filler creates a pre-formed protective layer that ensures thermal stability is built-in before the separator is installed in the battery, simplifying the overall manufacturing process while maintaining high thermal stability
Solution Approach 2:
The patent uses a porous structure for the heat-resistant porous layer with controlled porosity to maintain ion permeability while providing thermal stability. The porous structure allows lithium ion transport through the layer while the crosslinked siloxane binder and inorganic filler framework provide heat resistance and prevent short-circuits during thermal events
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 separator enhances the cycle-life characteristics and thermal stability of the battery, preventing short-circuits and maintaining performance even during overheating, thereby ensuring safer and more efficient lithium ion transport.
Implementation Method 1
The crosslinked binder has a cross-linked structure of a crosslinkable compound including a siloxane compound
Implementation Method 2
improved heat resistance and oxidation resistance, which ensures excellent electrolyte solution wettability
Implementation Method 3
maintaining performance even during overheating, thereby ensuring safer and more efficient lithium ion transport
Data Source
AI summary
A separator for a rechargeable lithium battery includes a substrate and a heat-resistant porous layer on at least one side of the substrate. The heat-resistant porous layer includes a crosslinked binder. The crosslinked binder has a cross-linked structure of a crosslinkable compound including a siloxane compound. The siloxane compound includes a siloxane resin including a unit represented by the chemical formula R1SiO3/2, where R1 is a curable reactive group, or an organic group having a curable reactive group.