Electrolytic Copper Foil Drum Side Hardness Control
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Solution Overview
Problem
Conventional electrolytic copper foils for lithium-ion batteries suffer from mechanical defects such as wrinkles and cracks during the coating and pressing process, leading to reduced production yield and cycle performance due to differences in stress endurance between the drum side and deposited side.
Innovation Solution
The electrolytic copper foil is manufactured with specific nanoindentation hardness and lightness ranges for the drum side, achieved by moistening the cathode drum surface before electroplating and optimizing polishing and spraying conditions, to enhance mechanical properties and prevent damage during the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the electrolytic copper foil is used for electrode manufacturing with coating and pressing processes, then the battery production can proceed, but wrinkles and cracks form on the copper foil due to stress differences between drum side and deposited side
Solution Approach 1:
The patent applies local quality by treating only the drum side of the copper foil with electrolyte solution, while the deposited side remains untreated. This localized treatment modifies the surface properties and stress characteristics of the drum side specifically, creating a gradient in material properties that accommodates differential stress during pressing without causing wrinkles or cracks.
Solution Approach 2:
The patent changes the physical-chemical parameters of the drum side surface by exposing it to electrolyte solution, which alters surface tension, wettability, and mechanical properties. This parameter modification allows the drum side to better withstand pressing stresses, preventing deformation and maintaining copper foil integrity throughout the battery manufacturing process.
2Ease of manufacture
If conventional electrolytic copper foil is used, then manufacturing cost is low, but mechanical properties are insufficient leading to breakage and reduced cycle performance
Solution Approach 1:
The patent applies preliminary action by treating the drum side with electrolyte solution before the copper foil undergoes coating and pressing operations. This pre-treatment modifies the surface characteristics and mechanical properties in advance, enabling the copper foil to withstand subsequent processing stresses and improve overall mechanical performance without adding significant manufacturing complexity.
3Device complexity
If the drum side and deposited side have different surface characteristics from electrolytic manufacturing, then production process is simple, but stress endurance during pressing is insufficient
Solution Approach 1:
The electrolyte solution acts as an intermediary substance that modifies the drum side surface properties. By introducing this chemical intermediary, the patent creates a transition layer that mediates between the manufacturing process requirements and the mechanical performance requirements, enabling the copper foil to endure pressing stresses while maintaining manufacturing simplicity.
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
This approach improves the mechanical properties of the electrolytic copper foil, reducing breakage and wrinkles, thereby increasing production yield and extending the cycle life and service life of lithium-ion batteries.
Implementation Method 1
spraying an electrolyte on the upper half of a cathode drum
Implementation Method 2
spraying an electrolyte on the upper half of a cathode drum which may be polished
Implementation Method 3
a device for manufacturing an electrolytic copper foil by further plating a drum side
Implementation Method 4
The nanoindentation hardness is represented by a value measured via a nanoindentation system adopting a Berkovich indenter with a curvature radius of equal to or smaller than 50 nm, and the indenter pressed the surface of the electrolytic copper foil at a speed of 0.04 mm/sec until an indentation depth of 300 nm
Data Source
Figure 1
AI summary
Provided are an electrolytic copper foil (70), an electrode comprising the same, and a lithium ion battery comprising the same. The electrolytic copper foil (70) has a drum side (701) and a deposited side (702) opposing to the drum side (701), wherein a nanoindentation hardness of the drum side (701) is equal to or larger than 0.5 GPa and equal to or smaller than 3.5 GPa; and a lightness of the drum side (701) is equal to or larger than 25 and equal to or smaller than 75.