Coated Battery Separators With Extended Thermal Shutdown Window
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Solution Overview
Problem
Current battery separators face challenges in thermal runaway safety, as they often fail to shut down effectively at lower temperatures while maintaining mechanical properties, and struggle with preventing shorts caused by lithium dendrites, which can lead to thermal runaway and reduced battery efficiency.
Innovation Solution
A coating composition for battery separators comprising a polymeric binder, heat-resistant particles, and additional components such as cross-linkers, low-temperature shutdown agents, adhesion agents, thickeners, friction-reducing agents, and high-temperature shutdown agents, which enhance thermal stability, shutdown performance, and adhesion to electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a coating is applied to improve high-temperature stability, then thermal safety performance is improved, but shutdown performance at lower temperatures deteriorates
Solution Approach 1:
The coating composition incorporates different functional components with distinct temperature-dependent properties: heat-resistant particles (e.g., alumina, silica) provide high-temperature stability, while low-temperature shutdown agents (e.g., polyethylene, polypropylene) enable shutdown at lower temperatures. This local differentiation of functional properties within the same coating resolves the contradiction between maintaining structural integrity at high temperatures and enabling shutdown at lower temperatures.
Solution Approach 2:
The coating is formulated as a composite material containing multiple phases: a polymeric binder matrix, dispersed heat-resistant inorganic particles, and low-temperature shutdown agents. This composite structure allows simultaneous achievement of thermal stability (from heat-resistant particles) and shutdown functionality (from low-temperature agents) that would be impossible with a single material system.
2Temperature
If ceramic particles are added to improve thermal stability, then heat resistance is improved, but adhesion to electrodes deteriorates
Solution Approach 1:
A polymeric binder serves as an intermediary material that chemically or physically bonds to both the heat-resistant ceramic particles and the electrode surfaces. The binder matrix (e.g., polyvinylidene fluoride, carboxymethyl cellulose) provides adhesion functionality while allowing heat-resistant particles to be embedded within it, thus transferring thermal stability to the coating without compromising adhesion.
3Reliability
If coating thickness is increased to improve safety performance, then thermal stability is improved, but ionic conductivity deteriorates
Solution Approach 1:
The coating is designed with a porous or semi-porous structure that allows ionic transport through the coating layer. The heat-resistant particles and binder are arranged to create interconnected voids or channels that facilitate electrolyte penetration and ion conduction, enabling the coating to provide thermal protection without blocking ionic flow essential for battery operation.
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 coating composition extends the shutdown window of battery separators, providing improved safety by initiating shutdown at lower temperatures and maintaining mechanical integrity, while also reducing the risk of shorts and improving adhesion and thermal stability.
Implementation Method 1
heat-resistant particles... enhance thermal stability
Implementation Method 2
low-temperature shutdown agent... initiating shutdown at lower temperatures
Implementation Method 3
adhesion agent... improving adhesion to electrodes
Implementation Method 4
cross-linker... maintaining mechanical integrity
Data Source
AI summary
New and/or improved coatings for porous substrates, including battery separators or separator membranes, and/or coated porous substrates, including coated battery separators, and/or batteries or cells including such coatings or coated separators, and/or related methods including methods of manufacture and/or of use thereof are disclosed. Also, new or improved coatings for porous substrates, including battery separators, which comprise at least a polymeric binder and heat-resistant particles with or without additional additives, materials or components, and/or to new or improved coated porous substrates, including battery separators, where the coating comprises at least a polymeric binder and heat-resistant particles with or without additional additives, materials or components are disclosed. Further, new or improved coatings for porous substrates, including battery separators, and new and/or improved coated porous substrates, including battery separators, new or improved coatings for porous substrates, including battery separators, which comprise at least (i) a polymeric binder, (ii) heat-resistant particles, and (iii) at least one component selected from the group consisting of a cross-linker, a low-temperature shutdown agent, an adhesion agent, and a thickener, and new and/or improved coated porous substrates, including battery separators, where the coating comprises at least (i) a polymeric binder, (ii) heat-resistant particles, and (iii) at least one component selected from the group consisting of a cross-linker, a low-temperature shutdown agent, an adhesion agent, a thickener, a friction-reducing agent, a high-temperature shutdown agent are disclosed.