Battery Separator Coating for Thin-Layer Adhesion and Ion Conductivity
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Solution Overview
Problem
Existing separators in electrochemical apparatuses, such as lithium-ion batteries, face challenges in improving cycle performance and energy density due to inadequate bonding forces between the separator and electrode plates, which affect ion conductivity and overall performance.
Innovation Solution
A separator design featuring an inorganic coating with embedded polymer particles, optimized ratios and dimensions, and a bonding layer to enhance bonding forces and ion conductivity, thereby improving energy density, kinetic performance, and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the separator thickness is reduced to improve energy density, then the energy density increases, but the bonding force between separator and electrode plates deteriorates
Solution Approach 1:
The separator employs a composite structure comprising a substrate layer, an inorganic coating layer containing inorganic particles, and a bonding layer with polymer particles. This multi-layer composite design enables the separator to maintain adequate bonding force while reducing overall thickness, as each layer contributes specific functions: the substrate provides mechanical support, the inorganic coating enhances thermal stability and ion conductivity, and the bonding layer ensures strong adhesion to electrode plates.
Solution Approach 2:
The separator applies local quality enhancement by concentrating functional materials at specific locations and interfaces. The inorganic coating is applied specifically at the interface between the substrate and bonding layer, creating a localized region with enhanced properties. The polymer particles are distributed non-uniformly within the bonding layer, with higher concentration near the inorganic coating interface, optimizing bonding force where it is most needed while minimizing overall material usage.
2Quantity of substance
If the bonding layer thickness is reduced to improve energy density, then the energy density increases, but the ion conductivity deteriorates
Solution Approach 1:
The bonding layer is designed as a porous structure containing distributed polymer particles, creating interconnected channels for ion transport. This porous architecture allows the thin bonding layer to maintain high ion conductivity by providing multiple pathways for ion flow, while the polymer particles within the pores enhance bonding force through mechanical interlocking with the inorganic coating and electrode plates.
3Quantity of substance
If the inorganic coating thickness is reduced to improve energy density, then the energy density increases, but the puncture resistance deteriorates
Solution Approach 1:
The inorganic coating is applied locally at the interface between the substrate and bonding layer, creating a concentrated region of enhanced mechanical strength and thermal stability. This localized application provides sufficient puncture resistance at the critical interface where stress concentration occurs, while minimizing the overall thickness and material usage of the separator.
Solution Approach 2:
The inorganic coating consists of inorganic particles embedded in a binder matrix, forming a composite structure that combines the high strength and thermal stability of inorganic particles with the flexibility and adhesion of the organic binder. This composite structure provides adequate puncture resistance in a thin layer, enabling energy density improvement without sacrificing mechanical integrity.
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 design enhances ion conductivity, maintains good kinetic and low-temperature performance, and improves cycle performance by increasing bonding forces and mechanical strength, leading to better energy density and prolonged service life of electrochemical apparatuses.
Implementation Method 1
At least part of the polymer particles are embedded in pores of the inorganic coating
Implementation Method 2
maintain good ion conductivity
Implementation Method 3
At least part of the polymer particles are embedded in pores of the inorganic coating
Implementation Method 4
bonding forces between the separators and positive and negative electrode plates
Data Source
AI summary
A separator includes a substrate layer, an inorganic coating and a bonding layer. The inorganic coating is disposed between the substrate layer and the bonding layer and includes inorganic particles, the bonding layer includes polymer particles, and at least part of the polymer particles are embedded in pores of the inorganic coating; and in a scanning electron microscope image of a cross section of the separator at a magnification of 2000, within an area of 11.6 μm×7.6 μm, the number of polymer particles embedded in the inorganic coating at a depth greater than or equal to 100 nm is C, and the total number of polymer particles in the cross section is D, where 0.5≤C/D<0.94.