Surface-Treated Copper Foil for Battery Current Collectors
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Solution Overview
Problem
Existing copper foils used as current collectors in battery cells face issues with insufficient adhesiveness to active substances and detachment of roughening particles, particularly due to heterogeneous accumulation of bloated roughening particles formed by copper sulfate plating.
Innovation Solution
A surface-treated copper foil with a primary particle layer and a secondary particle layer, where the surface treatment layer has a ten-point average roughness Rz of 1.8 μm or more, enhancing adhesiveness and preventing particle detachment, and containing elements like Cu, W, Ti, As, V, Mo, Ni, Co, Cr, Zn, P, and Sn in specific amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a roughening treatment layer is provided on a copper foil by roughening plating, then the adhesiveness between the current collector and active substance is improved, but the roughening particles are frequently detached
Solution Approach 1:
The surface treatment layer is divided into multiple layers: a primary particle layer containing roughening particles for adhesiveness, and an intermediate layer and outer layer that prevent particle detachment. This segmentation allows each layer to perform its specific function independently.
Solution Approach 2:
The patent uses a composite structure with different material compositions in each layer. The primary particle layer contains roughening particles (e.g., Cu, Ni, Co), while the intermediate layer contains different materials (e.g., Cu-Sn alloy, Cu-Ni alloy) that provide both adhesion and particle retention properties.
2Strength
If unevenness is formed by abrading the copper foil with emery paper, then the adhesiveness is improved, but sufficient adhesiveness cannot be obtained
Solution Approach 1:
The patent controls the ten-point average roughness Rz within a specific range (1.5 μm to 3.0 μm) to achieve optimal adhesiveness. This parameter control ensures sufficient surface unevenness for adhesion while maintaining manufacturing precision and consistency.
3Strength
If the ten-point average roughness Rz is increased to improve adhesiveness, then the adhesiveness to active substance is improved, but the surface treatment complexity increases
Solution Approach 1:
The patent applies different properties to different parts of the surface treatment layer. The primary particle layer has high roughness for adhesion, while the intermediate and outer layers have smoother surfaces and different compositions to prevent particle detachment and provide additional functionality.
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 surface-treated copper foil achieves improved adhesiveness to active substances, reduced particle detachment, and enhanced heat resistance, making it suitable for battery cell applications.
Implementation Method 1
the surface of the copper foil is abraded with emery paper to form unevenness, which targets the improvement in adhesiveness
Implementation Method 2
the surface of the surface treatment layer of the surface-treated copper foil for a battery cell has a ten-point average roughness Rz of 1.8 μm or more measured with a laser microscope with a wavelength of 405 nm
Data Source
AI summary
The invention provides a surface-treated copper foil for a battery cell that is capable of providing good adhesiveness to an active substance and undergoes less detachment of roughening particles.The surface-treated copper foil for a battery cell according to one or more embodiments of the present application contains a copper foil and a surface treatment layer on at least one surface of the copper foil, wherein the surface treatment layer contains a primary particle layer and a secondary particle layer, and the surface of the surface treatment layer has a ten-point average roughness Rz of 1.8 μm or more measured with a laser microscope with a wavelength of 405 nm according to JIS B0601 1994.