Lithium Battery Separator with Organic-Inorganic Coatings
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Solution Overview
Problem
Rechargeable lithium batteries face safety issues due to inadequate shut-down functions of separators, leading to heat generation and potential short circuits during thermal runaway, which existing technologies fail to adequately prevent.
Innovation Solution
A rechargeable lithium battery design featuring a separator with a substrate coated on one side with an organic material and the other side with an inorganic material, enhancing the shut-down function by blocking pores and reducing shrinkage, thereby preventing heat generation and short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional separator is used in the battery, then the battery can operate normally, but the separator cannot sufficiently perform its insulation and shut-down functions when thermal runaway occurs
Solution Approach 1:
The separator is constructed as a composite structure consisting of a base separator layer and a heat-resistant porous layer. The base separator provides the primary shut-down function through its melting characteristics, while the heat-resistant porous layer containing ceramic particles maintains structural integrity and electrical insulation even at elevated temperatures during thermal runaway events.
Solution Approach 2:
Different regions of the separator have different properties: the base separator layer has low melting point characteristics for shut-down function, while the heat-resistant porous layer has high temperature stability for maintaining insulation during thermal runaway. This local differentiation allows each layer to perform its specific function optimally.
2Reliability
If the separator thickness is increased to improve insulation, then electrical insulation is enhanced, but the battery's heat dissipation capability is reduced
Solution Approach 1:
The heat-resistant porous layer contains numerous pores that facilitate heat dissipation through convection and radiation pathways. This porous structure allows the separator to maintain adequate thickness for electrical insulation while simultaneously enabling effective heat transfer away from the electrode interface during thermal events.
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 reinforced shut-down function effectively suppresses heat generation and prevents short circuits, improving the safety and performance of lithium batteries by maintaining electrical insulation and reducing thermal runaway risks.
Implementation Method 1
a first layer on the first side of the substrate and comprising an organic material; and a second layer on the second side of the substrate and comprising an inorganic material
Implementation Method 2
the separator may not be able to sufficiently (or adequately) perform its insulation and shut-down functions... suppress heat generation of the battery early
Data Source
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AI summary
A rechargeable lithium battery includes a positive electrode, a negative electrode, and a separator between the positive electrode and the negative electrode. The separator includes a substrate having a first side facing the negative electrode and a second side facing the positive electrode. A first layer is positioned on the first side of the substrate and includes an organic material, and a second layer is positioned on the second side of the substrate and includes an inorganic material.