Polymer-Cluster Battery Separator for High-Temperature Shutdown Stability
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Solution Overview
Problem
Rechargeable lithium batteries face challenges with heat resistance and safety issues due to rapid temperature increases during external short circuits, leading to potential heat explosions, which existing separators with heat-meltable resins fail to adequately address, especially in large batteries.
Innovation Solution
A separator for rechargeable lithium batteries featuring a substrate with an adhesive coating layer containing polymer clusters and a ceramic layer, providing enhanced heat resistance and adherence to electrodes, thereby improving cycle-life characteristics and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator using heat-meltable resin is used to achieve shutdown function, then heat generation is suppressed when temperature reaches melting point, but the separator completely melts down during rapid temperature increase causing short circuit and heat explosion
Solution Approach 1:
The patent uses a composite structure consisting of a polyolefin base layer (providing shutdown function) coated with an organic-inorganic composite coating layer containing inorganic particles and binder polymer. This composite structure allows the separator to maintain mechanical strength at high temperatures while preserving the shutdown function of the polyolefin base layer.
Solution Approach 2:
The patent modifies the separator structure by adding a coating layer with specific thermal properties. The coating layer contains inorganic particles that maintain structural integrity at high temperatures, changing the overall thermal behavior parameters of the separator to prevent complete melting while retaining shutdown capability.
2Temperature
If organic-inorganic composite coating is applied to prevent shrinkage, then heat resistance is improved, but the effects for preventing shrinkage during overheating are insufficient
Solution Approach 1:
The patent optimizes the coating layer composition by selecting specific binder polymers with appropriate glass transition temperatures and molecular weights, and controlling the content of inorganic particles. This parameter optimization ensures the coating layer maintains flexibility and adhesion at high temperatures, effectively preventing separator shrinkage during overheating events.
Solution Approach 2:
The coating layer is applied specifically on the surface of the polyolefin base layer, creating a localized protective structure. This local quality enhancement provides targeted shrinkage prevention at the separator surface while maintaining the overall shutdown function of the base layer.
3Object-generated harmful factors
If heat-meltable resin separator is used to block pores and terminate reaction, then thermal runaway is suppressed, but rapid temperature increase causes complete melting and contact between electrodes
Solution Approach 1:
The composite structure of polyolefin base layer with organic-inorganic coating layer creates a hierarchical protection system. The coating layer prevents complete melting and maintains physical separation between electrodes during rapid temperature increases, while the base layer provides pore blocking shutdown function to suppress heat generation.
Solution Approach 2:
The coating layer acts as a protective cushion applied beforehand on the separator surface. This pre-applied protective layer prevents direct contact between electrodes even when the underlying polyolefin layer softens or melts during thermal events, cushioning against the harmful effect of short circuits.
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 proposed separator design achieves excellent heat resistance and adherence, leading to improved thermal stability, safety, and extended cycle-life characteristics in lithium batteries by reducing interfacial resistance and maintaining mechanical strength.
Implementation Method 1
an adhesive coating layer formed on the substrate, and including a polymer cluster
Implementation Method 2
the separator is melted and blocked the pores to terminate the battery reaction
Data Source
AI summary
Provided are a separator for a rechargeable lithium battery and a rechargeable lithium battery comprising the same, the separator for a rechargeable lithium battery comprising a substrate and an adhesive coating layer, on one surface of the substrate, and comprising polymer clusters.