Lithium Battery Separator Coating with 3D Fillers and Nanowires
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Solution Overview
Problem
Rechargeable lithium batteries face challenges in achieving high capacity and safe operation due to the need for a separator with enhanced heat resistance and reduced thickness, which existing separators fail to provide effectively.
Innovation Solution
A separator for rechargeable lithium batteries is developed, featuring a coating layer with three-dimensional structured particles and wire-type particles, where the wire-type particles fill empty spaces between the three-dimensional structured particles, increasing packing density and heat resistance, even when the separator is thinly formed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of the separator is reduced to increase battery capacity, then the battery capacity is improved, but the heat resistance of the separator deteriorates
Solution Approach 1:
The patent applies composite materials by combining three-dimensional structured particles (such as alumina, silica, or titania) with wire-type particles (such as boehmite or alumina nanowires) to form a coating layer on the separator. This composite structure provides both the thin profile needed for high battery capacity and the enhanced heat resistance through the synergistic effects of the different particle types, particularly the wire-type particles that form a heat-resistant network structure.
Solution Approach 2:
The patent applies local quality by creating a coating layer with specific local structures on the separator surface. The three-dimensional structured particles provide base coverage while wire-type particles are locally distributed to fill empty spaces and form heat-resistant pathways. This localized enhancement of heat resistance through the coating layer allows the bulk separator to remain thin for high capacity while specific regions provide enhanced thermal protection.
2Quantity of substance
If the thickness of the separator is reduced to increase battery capacity, then the battery capacity is improved, but the structural stability of the separator deteriorates
Solution Approach 1:
The patent uses composite materials consisting of three-dimensional structured particles combined with wire-type particles to form a coating layer that enhances structural stability. The wire-type particles, with their high aspect ratio, create a interconnected network structure that reinforces the coating layer, preventing structural degradation even when the overall separator thickness is reduced to increase battery capacity.
Solution Approach 2:
The patent utilizes the three-dimensional structured particles with curved or spherical surfaces to create a stable base structure in the coating layer. These rounded particles provide structural integrity and resistance to deformation, while the wire-type particles fill the interstices to further reinforce the structure, maintaining stability in the thinned separator.
3Temperature
If a coating layer is added to enhance heat resistance, then the heat resistance is improved, but the thickness of the separator increases
Solution Approach 1:
The patent employs porous materials by using three-dimensional structured particles with controlled porosity as the base coating material. These particles create a highly porous structure that provides excellent heat resistance through their inherent thermal stability while occupying minimal space. The wire-type particles fill the larger pores, further enhancing heat resistance without significantly increasing thickness, as the porous structure allows for high surface area and heat dissipation in a compact form.
Solution Approach 2:
The patent utilizes nanoscale wire-type particles that, despite their small individual size and potential short lifespan, provide disproportionate heat resistance enhancement. These fine particles can be applied in very thin layers, forming a dense network that blocks heat propagation effectively. Their small size allows them to be incorporated into ultra-thin coating layers without significantly increasing overall separator thickness.
Data Source
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AI summary
A separator for a rechargeable lithium battery and a rechargeable lithium battery including the same are disclosed. For example, provided is a separator for a rechargeable lithium battery including a substrate and a coating layer on at least one surface of the substrate; the coating layer includes three-dimensional structured particles including an organic filler; and wire-type particles. An average length (D50) of the wire-type particles is at least 5 times as large as their average diameter (D50) measured by scanning electronic microscope (SEM) analysis.