Battery Separator Inorganic Layer for Heat-Resistant Insulation
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Solution Overview
Problem
Existing energy storage devices, such as nonaqueous secondary batteries, face challenges in maintaining high electric resistance between electrodes when heat is generated due to abnormal handling, which can lead to short circuits.
Innovation Solution
The energy storage device incorporates an electrode with a mixture layer containing active material particles having two or more peaks in their volume-based particle size distribution, and a separator with an inorganic layer facing the mixture layer. The inorganic layer is composed of inorganic particles with an average particle diameter of 1.2 μm or less, which enhances insulation properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator with a heat-resistant porous layer containing filler is used, then short circuit prevention is improved, but electric resistance decreases at the time of heat generation
Solution Approach 1:
The invention changes the particle size parameter of the inorganic particles to 1.2 μm or less, which fundamentally alters the separator's behavior during heat generation. This parameter change enables the separator to maintain high electric resistance while still preventing short circuits, resolving the contradiction between short circuit prevention and resistance maintenance.
Solution Approach 2:
The invention uses a composite structure combining a thermoplastic resin layer with an inorganic particle layer. This composite material approach allows the separator to exhibit both short circuit prevention capabilities (through the heat-resistant inorganic layer) and high electric resistance maintenance (through the specific particle size of 1.2 μm or less), simultaneously addressing both requirements.
2Reliability
If the thermoplastic resin of the separator is melted, then short circuit prevention is improved, but electric resistance decreases between electrodes
Solution Approach 1:
The invention changes the particle size parameter of inorganic particles to 1.2 μm or less, which fundamentally alters how the separator behaves when the thermoplastic resin melts. This parameter change enables the inorganic particles to maintain their structural integrity and insulation properties even when the resin layer softens, preventing both short circuits and resistance loss.
Solution Approach 2:
The inorganic particles act as an intermediary substance between the thermoplastic resin and the electrodes. When the resin melts during heat generation, the inorganic particles maintain the separator's structural integrity and insulation properties, mediating between the softened resin and the electrodes to prevent both short circuits and resistance decrease.
Data Source
AI summary
One aspect of the present invention is an energy storage device including: an electrode having a mixture layer containing active material particles; and a separator having an inorganic layer facing the mixture layer, the inorganic layer containing inorganic particles, in which the active material particles have two or more peaks in volume-based particle size distribution, and an average particle diameter of the inorganic particles is 1.2 μm or less.