Copper Foil A-Value Control for Thin Battery Electrode Strength
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Solution Overview
Problem
The existing copper foils used as anode current collectors in secondary batteries face challenges with strength, curling, wrinkling, and tearing during manufacturing, particularly when thin, which affects their performance and capacity retention.
Innovation Solution
A copper foil with an A-value ranging from 1.1 to 1.6 is developed, formed using a process involving a copper film with a protective layer, and an electrolyte containing specific concentrations of copper ions, sulfuric acid, chlorine, nickel, lead ions, hydrogen peroxide, tungsten, and organic additives, ensuring high strength and preventing curling, wrinkling, and tearing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of the copper foil is decreased to increase the amount of active material, then the charge/discharge capacity is improved, but the strength of the copper foil is reduced and the possibility of breaking is increased
Solution Approach 1:
The patent applies parameter changes by controlling the A-value (a specific parameter related to copper foil properties) within a predetermined range of 1.05 to 1.30. This parameter control enables the copper foil to achieve both reduced thickness (6 μm to 15 μm) for increased active material capacity and maintained high strength (40 kg/mm² or more) to prevent breaking during manufacturing and battery operation.
2Quantity of substance
If the thickness of the copper foil is decreased to increase the amount of active material, then the charge/discharge capacity is improved, but the handling difficulty and curling/wrinkling/tearing during manufacturing are increased
Solution Approach 1:
The patent controls the A-value parameter within 1.05 to 1.30 to achieve optimal balance between thickness reduction and manufacturing handleability. This parameter optimization prevents curling, wrinkling, and tearing during the winding and manufacturing processes while maintaining the reduced thickness needed for high active material content.
Solution Approach 2:
The patent applies preliminary action by controlling the A-value and composition of the copper foil before the battery assembly process. This preliminary optimization of copper foil properties ensures that the foil maintains its shape and strength throughout subsequent manufacturing steps, preventing defects before they occur during assembly and winding operations.
3Strength
If the A-value is increased to improve tensile strength, then the strength and handling properties are improved, but the surface roughness may increase affecting manufacturing quality
Solution Approach 1:
The patent optimizes the A-value parameter within a specific range (1.05 to 1.30) to achieve the optimal balance between tensile strength and surface quality. This precise parameter control ensures that the copper foil attains sufficient strength (40 kg/mm² or more) while maintaining smooth surface characteristics suitable for high-quality manufacturing and electrode coating.
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 copper foil exhibits high tensile strength, improved elongation, and reduced surface roughness, enhancing the charge/discharge efficiency and lifespan of secondary batteries by preventing defects during manufacturing and usage.
Implementation Method 1
forming a copper film, wherein the forming of the copper film includes forming the copper film on a rotating anode drum by electrically connecting a cathode plate and the rotating anode drum
Implementation Method 2
hydrogen peroxide at a concentration of 1 ml/L to 10 ml/L
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, wherein the copper film has an A-value in a range of 1.1 to 1.6. “A” is calculated by Equation 1 below,A=P/Q[Equation 1]wherein “P” in Equation 1 is a peak intensity at 1650 cm−1 of the copper film, “Q” in Equation 1 is a peak intensity at 1460 cm−1 of the copper film, and the peak intensity is measured by Fourier-transform infrared spectroscopy (FT-IR).