Porous Polyimide Separator Coating for Dendrite and Thermal Runaway
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Solution Overview
Problem
High energy and high voltage rechargeable lithium batteries face safety issues due to dendrite growth and thermal runaway, which are not adequately addressed by existing ceramic coated separators and gel or polymer electrolytes.
Innovation Solution
A polyimide coated separator with a porous or microporous polyimide layer on a polymeric base layer, designed to prevent dendrite growth, provide oxidation resistance, and block ionic flow during thermal runaway, while maintaining ion conductivity and mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ceramic coated separators are used to prevent dendrite growth and thermal runaway, then safety is improved, but manufacturing complexity and cost increase due to coating processes and material handling
Solution Approach 1:
The patent uses a composite structure combining a polyolefin base layer (providing shutdown function) with a ceramic coating layer (providing thermal stability and dendrite blocking). This composite approach allows each layer to contribute its specific properties, achieving high safety standards while using simpler, more compatible manufacturing processes compared to alternative complex coatings
Solution Approach 2:
The ceramic coating is applied as a porous layer that maintains ion conductivity while providing physical barriers against dendrites. The porous structure allows lithium ion transport necessary for battery operation while the ceramic material itself provides thermal stability and mechanical strength to prevent short circuits during thermal runaway events
2Reliability
If gel or polymer electrolytes are used to address safety issues, then thermal runaway resistance is improved, but ion conductivity decreases compared to liquid electrolytes
Solution Approach 1:
The patent separates the functions of safety and ion conduction into different components: the polyolefin separator provides thermal safety and shutdown functionality, while the liquid electrolyte maintains high ion conductivity. This segmentation allows each component to optimize its specific function without compromising the other, avoiding the trade-off present in gel or polymer electrolyte systems
3Reliability
If separator thickness is increased to block dendrites and prevent shorting, then safety is improved, but ion conductivity and battery performance deteriorate
Solution Approach 1:
The patent applies local quality enhancement by coating the separator surface with ceramic material that provides dendrite-blocking properties specifically where needed (at the electrode interface), rather than increasing the overall thickness of the separator. This localized approach maintains high ion conductivity in the bulk separator while providing enhanced safety at critical interfaces
Solution Approach 2:
Instead of solving the dendrite blocking problem by increasing separator thickness in the vertical dimension, the patent adds functionality in the horizontal dimension through surface coating. The ceramic coating layer provides dendrite protection as a surface property rather than a bulk property, allowing thin separators to achieve high safety standards
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 polyimide coated separator effectively prevents electronic shorting and ionic flow, enhancing safety and performance of high energy and high voltage lithium batteries by blocking dendrites and maintaining structural integrity under extreme conditions.
Implementation Method 1
The microporous polymeric base layer may be adapted, at least, to hold liquid, gel, or polymer electrolyte, to conduct ions
Implementation Method 2
The polyimide coating may be adapted, for example, to provide oxidation resistance
Implementation Method 3
The polyimide coating may be adapted, for example, to block dendrite growth
Implementation Method 4
The polyimide coating may be adapted, for example, to prevent electronic shorting at temperatures above 200 deg C.
Data Source
AI summary
The instant disclosure or invention is preferably directed to a polyimide coated membrane, separator membrane, or separator for a lithium battery such as a high energy or high voltage rechargeable lithium battery and the corresponding battery. The separator preferably includes a porous or microporous polyimide coating or layer on at least one side of a polymeric microporous layer, membrane or film. The polyimide coating or layer may include other polymers, additives, fillers, or the like. The polyimide coating may be adapted, for example, to provide oxidation resistance, to block dendrite growth, to add dimensional and/or mechanical stability, to reduce shrinkage, to add high temperature performance (HTMI function), to prevent electronic shorting at temperatures above 200 deg C., and/or the like. The microporous polymeric base layer may be adapted, at least, to hold liquid, gel, or polymer electrolyte, to conduct ions, and/or to block ionic flow between the anode and the cathode in the event of thermal runaway (shutdown function). The polyimide coated separator may be adapted, for example, to keep the electrodes apart at high temperatures, to provide oxidation resistance, to block dendrite growth, to add dimensional stability, to reduce shrinkage, to add high temperature performance (HTMI function), to prevent electronic shorting at temperatures above 200 deg C., to increase puncture strength, and/or to block ionic flow between the anode and the cathode in the event of thermal runaway (shutdown function). Although secondary lithium battery usage may be preferred, the instant polyimide coated membrane may be used in a battery, cell, primary battery, capacitor, fuel cell, textile, filter, and/or composite, and/or as a layer or component in other applications, devices, and/or the like.