VDF Copolymer Composite Separator for Battery Safety
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Solution Overview
Problem
Inorganic composite membranes used as separators in electrochemical devices, such as secondary batteries, lack mechanical strength and are prone to breakdown during handling and assembly, compromising battery safety and performance due to high filler content and multiple coating steps increasing processing costs.
Innovation Solution
A process involving a porous polymeric substrate impregnated with a composition containing a fluoro copolymer derived from vinylidene difluoride (VDF) and functional groups, combined with an electrolyte composition including an ionic liquid and an alkoxysilane, forming a hybrid organic-inorganic network that enhances mechanical and ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If inorganic filler materials are used to fabricate inorganic composite membranes, then thermal stability and ionic conductivity are improved, but mechanical strength deteriorates and the membrane breaks down during handling
Solution Approach 1:
The patent uses a composite structure combining an organic binder polymer matrix with inorganic filler particles dispersed throughout. The organic binder provides mechanical strength and flexibility while the inorganic fillers contribute thermal stability and ionic conductivity, resolving the contradiction between these opposing properties
Solution Approach 2:
The membrane is designed with a porous structure where inorganic filler particles are distributed within the porous organic binder matrix. This porous architecture allows electrolyte penetration for ionic conductivity while the organic binder maintains structural integrity and mechanical strength
2Reliability
If inorganic particles are distributed throughout a polymeric binder matrix, then wettability by electrolytes and thermal stability are improved, but mechanical strength deteriorates and handling becomes difficult
Solution Approach 1:
The patent optimizes the ratio of inorganic filler to organic binder, controlling the concentration and distribution parameters to achieve sufficient wettability and thermal stability while maintaining adequate mechanical strength for handling. The specific formulation balances these parameters to avoid breakdown during manufacturing
3Strength
If multiple coating steps are used to obtain multilayer composite membranes, then mechanical strength and safety are improved, but processing costs increase
Solution Approach 1:
The patent combines the organic binder and inorganic fillers into a single composite coating composition that is applied in one coating step. This single-step process forms a unified multilayer-like structure where the organic-inorganic composite provides both mechanical strength and functional properties, eliminating the need for multiple separate coating steps
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 resulting composite material exhibits improved thermo-mechanical properties and ionic conductivity, enabling efficient assembly and prolonged service life of electrochemical cells with enhanced safety and performance.
Implementation Method 1
mixing, optionally in the presence of a liquid medium (L1), an electrolyte salt (ES-1), an ionic liquid (IL-1) and a compound (M) of formula (I) wherein X is a hydrocarbon group, optionally comprising one or more functional groups, m is an integer from 1 to 4, A is an element selected from the group consisting of Si, Ti and Zr, and Y is a hydrolysable group selected from the group consisting of an alkoxy group, an acyloxy group and a hydroxyl group
Data Source
AI summary
The present invention relates to a process for the preparation of a composite material comprising a vinylidene difluoride (VDF)-containing copolymer and an electrically non-conductive polymeric material, to a composite material obtainable via said process, to its use in electrochemical cells and to an electrochemical cell comprising said composite.