Composite Current Collector Coating for Low-Resistance Battery Electrodes
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Solution Overview
Problem
Conventional high-purity aluminum foils used as positive current collectors in non-aqueous secondary batteries have low surface energy, leading to poor adhesion of active materials and high interface resistance, which affects battery performance.
Innovation Solution
A composite current collector with a polymer base film and a two-layer aluminum coating, where the first sub-layer has small particles for high compactness and conductivity, and the second sub-layer has larger particles for increased surface energy, reducing interface resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a rolling process with a highly smooth roller surface is used to produce high-purity aluminum foils, then the flatness of the aluminum foils is guaranteed, but the surface energy of the current collector becomes low, leading to poor adhesion of active materials
Solution Approach 1:
The invention applies local quality by creating a multi-layer aluminum coating structure where each layer has different properties: the first sub-layer (near the polymer) has fine particles for smoothness and adhesion, while the second sub-layer (outer layer) has coarse particles for high surface energy. This resolves the contradiction by providing both flatness (through fine particles) and active material adhesion (through coarse particles with high surface energy) in different locations of the coating.
Solution Approach 2:
The invention uses composite materials by combining polymer base film with multi-layer aluminum coating, where each aluminum layer has different particle sizes. The composite structure integrates the flatness-providing polymer substrate with the surface-energy-providing aluminum coating, resolving the contradiction between flatness and adhesion.
2Ease of manufacture
If conventional high-purity aluminum foils are used as current collectors, then the structure is simple and manufacturing is easy, but the interface resistance between active material and current collector is overly large, affecting battery performance
Solution Approach 1:
The invention applies parameter changes by modifying the particle size distribution across different layers of the aluminum coating. The first sub-layer uses particles of 3-10 μm for smooth adhesion, while the second sub-layer uses particles of 10-30 μm for high surface energy and low interface resistance. This parameter variation resolves the contradiction between manufacturing simplicity and reduced interface resistance.
3Device complexity
If a single-layer aluminum coating is applied on the polymer base film, then the manufacturing process is simple, but it cannot simultaneously achieve high conductivity and high surface energy
Solution Approach 1:
The invention applies segmentation by dividing the aluminum coating into two distinct sub-layers with different particle sizes: the first sub-layer (3-10 μm) provides conductivity and smoothness, while the second sub-layer (10-30 μm) provides high surface energy. This segmentation resolves the contradiction by assigning different functions to different layers, achieving both high conductivity and high surface energy.
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 composite current collector achieves high conductivity and surface energy, improving the capacity and cycle performance of lithium batteries by reducing interfacial resistance.
Implementation Method 1
the aluminum coating layer is formed by vacuum evaporation or magnetron sputtering
Implementation Method 2
the aluminum coating layer is formed by vacuum evaporation or magnetron sputtering
Data Source
AI summary
A composite current collector and preparation method therefor, electrode plate and secondary battery. The current collector comprises a polymer base membrane, and aluminum-plated layers, which are arranged on surfaces of two sides of the polymer base membrane. The aluminum-plated layer comprises a first sub-layer and a second sub-layer; the first sub-layer is closer to the polymer base membrane than the second sub-layer; and the particle size of aluminum particles in the first sub-layer is 10 nm to 30 nm, and the particle size of aluminum particles in the second sub-layer is 80 nm to 100 nm. The current collector not only has relatively high conductivity, but also has relatively high surface energy; and during a coating process of an active substance, the interface internal resistance between a battery electrode plate and a current collector can be significantly improved, thereby improving the capacity and cycling performance of a lithium battery.