Lithium-Ion Battery Separator With Shape-Memory Thermal Sealing
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Solution Overview
Problem
Lithium-ion batteries (LIBs) are prone to heat generation and explosion due to lithium dendrites piercing the separator and uncontrolled reactions, leading to safety concerns.
Innovation Solution
A safe LIB separator is fabricated using a method involving a water-based slurry with ceramic material, magnesium oxide, and conductive carbon black, combined with a memory material that forms holes which automatically close at elevated temperatures to block electrolyte reaction, preventing short circuits and enhancing safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional separator is used, then lithium-ion batteries can operate, but the separator cannot prevent short circuits when lithium dendrites pierce it or block uncontrolled reactions at high temperatures
Solution Approach 1:
The separator is constructed as a composite structure combining an inert base membrane (polyolefin or ceramic) with a functional coating layer containing shape memory polymer and flame retardant. This composite design provides both mechanical integrity and active safety functions, resolving the contradiction between basic separator functionality and enhanced safety protection.
Solution Approach 2:
The separator utilizes phase transition of shape memory polymer at specific temperatures to change its physical state from open-pore to closed-pore configuration. This parameter change enables automatic response to thermal conditions, blocking ion transport when temperature exceeds safe thresholds while maintaining normal operation at lower temperatures.
2Reliability
If the separator structure is made more complex to improve safety, then short circuit prevention improves, but manufacturing difficulty increases
Solution Approach 1:
The shape memory polymer and flame retardant are pre-integrated into the separator structure during manufacturing, creating a pre-configured safety system. The separator is prepared in advance with embedded response mechanisms that automatically activate under specific conditions, eliminating the need for complex real-time control systems during battery operation.
Solution Approach 2:
The separator performs self-protection functions through the intrinsic properties of shape memory polymer that automatically changes pore configuration in response to temperature changes. This self-regulating mechanism eliminates the need for external control systems, sensors, or power sources, simplifying the overall manufacturing process while maintaining high reliability.
3Reliability
If a coating layer is added to the separator to block reactions, then safety improves, but the separator performance and ion transport may deteriorate
Solution Approach 1:
The separator coating transitions from a static structure to a dynamic, responsive system. The shape memory polymer coating maintains an open-pore configuration during normal operation to ensure efficient ion transport, then dynamically closes the pores when temperature exceeds the phase transition point, automatically blocking reactions while preserving productivity under normal conditions.
Solution Approach 2:
The separator utilizes a porous coating structure with controlled pore size and distribution. The porous architecture allows efficient ion transport during normal operation while providing a large surface area for the shape memory polymer and flame retardant to function. When activated, the pore closure mechanism blocks ion transport, preventing reactions without compromising normal productivity.
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 effectively blocks further electrolyte reaction at high temperatures, preventing lithium dendrites from causing short circuits and improving battery safety by automatically sealing when temperatures rise and opening when they fall.
Implementation Method 1
a reaction inside the battery cannot be blocked in time, resulting in a continuous reaction and generating dangerous consequences... the memory material that forms holes which automatically close at elevated temperatures
Implementation Method 2
coating the water-based slurry on the first film to form a first water-based slurry layer... drying the first composite film and the second composite film
Data Source
Figure 1~4
Figure 5
AI summary
The present disclosure discloses a safe lithium-ion battery (LIB) separator, a fabrication method thereof, and an LIB, and relates to the technical field of LIBs. The fabrication method includes the following steps: S1: preparation of a water-based slurry: mixing a ceramic material, magnesium oxide, conductive carbon black (CB), and a water-based adhesive, and thoroughly stirring to obtain the water-based slurry; S2: fabrication of a first film: adding trans-1,4-polyisoprene, cis-polybutadiene rubber (cis-BR), conductive CB, and a water-soluble salt to a compounding granulator for compounding to prepare a memory material; and mixing a high-polymer particle with the solid material, adding a resulting mixed material to a film-blowing machine, blowing the mixed material of the high-polymer particle and the solid material into a film by a film-blowing method, and watering and drying the film to obtain the first film; S3: fabrication of a second film; and S4: fabrication of the LIB separator. The present disclosure can block a reaction of an electrolyte when a temperature rises, such as to play the role of protecting batteries.