Coated Li-Ion Separator for Adhesion and Low-Temperature Rate Performance
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Solution Overview
Problem
Existing lithium-ion battery separators fail to balance adhesion and dynamic performance, leading to suboptimal charge and discharge capabilities, especially at low temperatures, which restricts the application of lithium-ion batteries.
Innovation Solution
A separator with a substrate and a first coating layer containing a polymer with controlled particle distribution, air permeability, and a heat-resistant layer, optimized for interface adhesion and ion transport, enhancing the battery's rate and cycle performance at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a coated separator is used to improve adhesion, then interface adhesion is enhanced, but dynamic performance deteriorates
Solution Approach 1:
The coating layer incorporates particles with different sizes (10-30 μm maximum length) distributed at specific densities (10-30 particles per 250 μm×200 μm area) to create local variations in structure. This local quality differentiation allows the coating to provide both adhesion strength and ion transport channels, resolving the contradiction between strong interface bonding and dynamic ion transport performance
Solution Approach 2:
The coating layer is designed with a porous structure formed by the particle distribution, creating channels for electrolyte ion transport. The controlled particle density and size generate void spaces that facilitate ion movement while maintaining structural integrity and adhesion, thus improving dynamic performance without sacrificing interface strength
2Productivity
If the air permeability of the separator is increased to improve ion transport, then rate performance is enhanced, but internal resistance increases
Solution Approach 1:
The air permeability is precisely controlled within the range of 500-10000 sec/100 mL by adjusting particle size distribution and coating density. This parameter optimization creates a balance where sufficient porosity exists for ion transport (improving rate performance) while maintaining appropriate density to prevent excessive internal resistance, resolving the contradiction between transport efficiency and energy loss
3Strength
If the coating surface density is increased to improve adhesion, then interface bonding is enhanced, but ion transport channels are blocked
Solution Approach 1:
The coating surface density is optimized to create local quality variations where particles are distributed at specific densities (10-30 particles per 250 μm×200 μm area). This controlled distribution ensures sufficient coating coverage for adhesion while maintaining local porosity for ion transport channels, resolving the contradiction between coating strength and ion transport capability
Solution Approach 2:
The coating layer is designed as a composite structure combining polymer matrix with dispersed particles of specific size ranges. This composite architecture provides both the adhesive properties from the polymer-coating interface and the ion transport pathways through the particle network, simultaneously achieving strong bonding and efficient ion transport
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 optimized separator improves the lithium-ion battery's rate and cycle performance, particularly at low temperatures, by ensuring excellent adhesion, ion transport, and structural stability, thereby enhancing its overall performance and application range.
Implementation Method 1
the first coating layer including a first polymer, the number of particles with a maximum length of 10 μm to 30 μm in the first polymer in any area of 250 μm*200 μm on a surface of the first coating layer being 10 to 30
Implementation Method 2
by controlling the number of particles with a maximum length of 10 μm to 30 μm in the first polymer to be within the above range, a point-like discrete distribution can be presented in the first coating layer, thus providing a channel for electrolyte liquid transport
Data Source
AI summary
A separator includes a substrate and a first coating layer provided on at least one surface of the substrate. The first coating layer includes a first polymer. The number of particles with a maximum length of 10 μm to 30 μm in the first polymer in any area of 250 μm*200 μm on a surface of the first coating layer is 10 to 30. The separator provided by this application has good interface adhesion performance and improves the structural stability of the lithium-ion battery, so that the lithium-ion battery has better charge and discharge performance, especially rate performance and cycle performance under low temperature.