Temperature-Responsive Separator Coating for Rechargeable Battery Safety
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium ion batteries face safety risks due to thermal runaway events caused by internal short circuits and overcharging, which can lead to excessive heat generation and potential explosions, and existing separator coatings do not adequately address these issues while maintaining optimal performance.
Innovation Solution
A temperature-responsive separator coating or film is developed, comprising a porous layer with materials that allow ion passage at normal temperatures but close pores upon elevated temperatures, thereby shutting down chemical reactions and reducing heat generation, while also enhancing air permeability through a shrinkable second material that increases porosity during the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat resistant layers are provided at the separator to prevent thermal runaway, then safety is improved, but air permeability deteriorates
Solution Approach 1:
The coating material changes its physical state and pore structure in response to temperature changes. At normal operating temperatures, the coating maintains an open porous structure with high air permeability for optimal battery performance. When abnormal temperature rise occurs, the coating undergoes phase transition or shrinkage to close pores, blocking ion transport and shutting down battery reactions to prevent thermal runaway.
Solution Approach 2:
The separator coating is designed with dynamic pore structure that can reversibly change between open and closed states. The coating material incorporates temperature-responsive components that dynamically adjust pore size and connectivity based on thermal conditions, allowing the separator to adapt its permeability characteristics in real-time to maintain safety while preserving performance.
2Reliability
If the separator coating is made dense to prevent thermal runaway, then safety is improved, but ion permeability deteriorates
Solution Approach 1:
The coating material changes its physical state and pore structure in response to temperature changes. At normal operating temperatures, the coating maintains an open porous structure with high air permeability for optimal battery performance. When abnormal temperature rise occurs, the coating undergoes phase transition or shrinkage to close pores, blocking ion transport and shutting down battery reactions to prevent thermal runaway.
Solution Approach 2:
The separator coating is designed with dynamic pore structure that can reversibly change between open and closed states. The coating material incorporates temperature-responsive components that dynamically adjust pore size and connectivity based on thermal conditions, allowing the separator to adapt its permeability characteristics in real-time to maintain safety while preserving performance.
3Reliability
If a coating layer is applied to the separator to provide thermal protection, then safety is improved, but manufacturing complexity increases
Solution Approach 1:
The separator coating utilizes a porous material structure that can be applied as a thin film layer on the separator surface. The porous structure provides thermal protection through controlled pore closure at elevated temperatures while maintaining ion permeability during normal operation. The coating can be manufactured using conventional techniques such as dip-coating, spray-coating, or lamination of pre-formed porous membranes.
Solution Approach 2:
The separator coating is formulated as a composite material system combining thermally responsive polymers, inorganic fillers, and binding agents. This composite structure provides synergistic effects where the polymer matrix offers thermal response, inorganic particles enhance thermal stability, and binders ensure adhesion to the separator. The composite nature allows tuning of transition temperature and mechanical properties to match specific battery requirements.
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 effectively prevents thermal runaway by automatically shutting down chemical reactions during abnormal conditions and maintains optimal performance by enhancing air permeability and ion transfer at normal temperatures.
Implementation Method 1
the second material of the porous layer is adapted to shrink or reduce in size upon drying, for example, due to a removal of solvent such as water during the preparation or manufacturing step
Implementation Method 2
in response to temperature change, the layer material is adapted to undergo a first phase change during which the pores of said porous layer are adapted to substantially close
Data Source
AI summary
The invention provides a coating or film adapted to be arranged between a separator and at least one electrode of a rechargeable battery. The coating or film comprises a porous layer comprising a layer material having at least a first material and a second material, the first and the second materials being arranged to comprise a plurality of pores for passage of ions therethrough; and the second material is adapted to reduce in size upon drying such that porosity of the porous layer is improved or enhanced at a normal operating temperature; wherein, in response to temperature change, the layer material is adapted to undergo a first phase change during which the pores of said porous layer are adapted to substantially close to thereby substantially reduce or prevent further passage of ions.