Lithium-Ion Battery Separator Coating for Dendrite and Heat Shutdown
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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 causing internal short circuits and uncontrolled reactions, posing safety risks.
Innovation Solution
A safe LIB separator is fabricated using a method that involves mixing ceramic materials, conductive carbon black, and a water-based adhesive to form a slurry, incorporating a memory material with phase transition properties to block electrolyte reactions at high temperatures, and coating this slurry on composite films to create a protective layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional separator is used in lithium-ion batteries, then the battery can operate normally with good ion conductivity, but the separator cannot prevent internal short circuits caused by lithium dendrites or block uncontrolled reactions at high temperatures
Solution Approach 1:
The separator is constructed as a composite structure combining a base separator layer with a safety coating layer containing phase-change materials and ceramic particles. This composite structure maintains the ion conductivity of the base separator while adding safety functions to block dendrites and prevent thermal runaway reactions.
Solution Approach 2:
The separator incorporates materials that change their physical properties at specific temperatures. The phase-change materials undergo solid-liquid transitions at predetermined temperature thresholds, causing the separator to automatically close pores and block ion transport when thermal runaway is detected, without requiring external control systems.
2Reliability
If the separator structure is enhanced to prevent dendrites and block reactions, then the safety is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The safety coating layer is pre-formed with embedded phase-change materials and ceramic particles before being applied to the base separator. This preliminary preparation of functional materials simplifies the overall manufacturing process by allowing modular assembly rather than requiring complex in-situ formation during separator production.
Solution Approach 2:
A water-based slurry serves as an intermediary medium to uniformly distribute and embed ceramic particles and phase-change materials into the coating layer. This slurry approach simplifies material integration by using a liquid carrier that can be easily applied and then dried, avoiding complex mixing or bonding processes.
3Object-affected harmful factors
If the separator uses advanced materials to block reactions at high temperature, then the safety is enhanced, but the cost of materials and processing increases
Solution Approach 1:
The advanced safety materials are concentrated in a thin coating layer applied only to the surface of the base separator, rather than throughout the entire separator structure. This localized application reduces the total quantity of expensive materials needed while maintaining effective protection where it is most needed—at the interface with electrolyte and electrodes.
Solution Approach 2:
The separator incorporates inexpensive ceramic particles and phase-change materials that provide effective safety functions at low concentrations. These materials are used in small quantities within the coating layer, making the overall cost increase minimal while achieving reliable thermal protection.
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 automatically seals at high temperatures to prevent further reactions, enhancing safety by blocking lithium-ion exchange and preventing short circuits, while reopening at normal temperatures to allow normal battery function.
Implementation Method 1
adding 5 to 10 parts of water-soluble salt to a compounding granulator for compounding to obtain a memory material... after the film is watered, the film is dried... holes are formed on the memory material
Implementation Method 2
incorporating a memory material with phase transition properties to block electrolyte reactions at high temperatures... When a temperature rises, the holes on the memory material can automatically close to block the further reaction of an electrolyte
Implementation Method 3
mixing a ceramic material, magnesium oxide, conductive carbon black (CB), and a water-based adhesive, and thoroughly stirring, to obtain the water-based slurry... coating the water-based slurry on the first film to form a water-based slurry layer on a surface of the first film
Data Source
AI summary
A safe lithium-ion battery (LIB) separator, a fabrication method thereof, and an LIB are provided. The fabrication method includes: 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; adding the memory material to a mixed solution of aluminum nitride and ethanol, and conducting stirring, suction filtration, drying and calcination to obtain a solid material; and mixing a high-polymer particle with the solid material, adding a resulting mixed material to a film-blowing machine, blowing into a film, and watering and drying the film to obtain the first film; S3: fabrication of a second film; and S4: fabrication of the LIB separator.