Copper Foil R-Value Control for Curl-Free Battery Electrodes
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Solution Overview
Problem
The challenge is to prevent curling, wrinkling, and tearing of copper foils during manufacturing, which affects the production of high-capacity and high-efficiency secondary batteries, as thinner foils are prone to defects that reduce battery performance and capacity.
Innovation Solution
A copper foil with an R value between 2.0 and 3.5 is developed, achieved by forming a copper film with a protective layer using a specific electrolyte composition and electroplating process, ensuring the foil's thickness and width stability during manufacturing, thereby preventing curling and enhancing tensile strength and elongation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If copper foil thickness is reduced to increase battery capacity, then the amount of active materials that can be included increases and battery capacity increases, but curling occurs and defects such as tears or wrinkles occur during manufacturing
Solution Approach 1:
The patent applies parameter changes by optimizing the R-value (a measure of material formability) to a specific range of 2.0 to 3.5. This parameter optimization enables the copper foil to maintain dimensional stability and prevent curling during manufacturing processes while achieving thin thickness specifications (6 μm to 35 μm) that increase battery capacity
Solution Approach 2:
The patent implements preliminary action through pre-treatment processes including acid cleaning, phosphating, and chromating before electroplating. These preliminary actions prepare the copper foil surface in advance to ensure proper adhesion and dimensional stability, preventing curling and defects during subsequent manufacturing steps
2Quantity of substance
If copper foil thickness is reduced to increase battery capacity, then the number of current collectors that can be increased, but curling occurs making it difficult to manufacture very thin film copper foils
Solution Approach 1:
The patent changes the R-value parameter to a specific range of 2.0 to 3.5, which fundamentally improves the ease of manufacture for thin film copper foils. This parameter optimization ensures that even at thicknesses of 6 μm or less, the foil maintains sufficient dimensional stability to be manufactured without curling defects
Solution Approach 2:
The patent applies beforehand cushioning through the application of a protective layer and surface treatment processes that cushion against dimensional changes during manufacturing. This prevents curling from occurring during handling and processing of very thin copper foils
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 solution effectively prevents curling and tearing, allowing for the production of copper foils with improved workability and reduced failure rates, enabling higher capacity and efficiency in secondary batteries while maintaining durability and charge/discharge efficiency.
Implementation Method 1
forming a copper film, wherein the electrolyte includes copper ions at a concentration of 70 g/L to 100 g/L
Implementation Method 2
forming a copper film by electrically conducting a cathode plate and a rotating anode drum, which are disposed to be spaced apart from each other, in the electrolyte
Data Source
AI summary
According to one embodiment of the present disclosure, there is provided a copper foil including a copper film including 99.9 wt % or more of copper, and having an R value in a range of 2.0 to 3.5.