Copper Foil Surface Tuning for Heat-Stable Battery Conductivity
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Solution Overview
Problem
Lithium secondary batteries face challenges in maintaining high charge/discharge capacity and conductivity due to limitations in copper foils used as anode current collectors, which are affected by surface resistivity and water contact angle, leading to reduced performance and stability during heat treatment.
Innovation Solution
A copper foil with a room temperature water contact angle between 60° to 70° and surface resistivity of 2.4 mΩ/cm to 2.7 mΩ/cm, combined with a protective layer, is manufactured using a specific electrolyte composition and process, ensuring stability and high conductivity even after heat treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional copper foil is used as anode current collector, then manufacturing cost is reduced, but conductivity and charge/discharge capacity are insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling the water contact angle (60°-70°) and surface resistivity (2.4-2.7 mΩ/cm) of the copper foil through electrolyte composition optimization. This involves adjusting electrolyte temperature (20°C-40°C), current density (2-10 A/dm²), and additive concentrations to achieve the target surface properties that ensure high conductivity while maintaining manufacturability through standardized electroplating processes
2Reliability
If copper foil surface is made more conductive, then charge/discharge capacity increases, but oxidation and corrosion resistance decreases
Solution Approach 1:
The patent resolves this contradiction by changing the surface parameter (water contact angle to 60°-70°) through controlled electroplating with specific additives (0.1-5 g/L wetting agents, 1-10 g/L brighteners). This creates an optimal surface state that balances conductivity with oxidation resistance, as the controlled surface morphology reduces reactive sites while maintaining electrical pathways
Solution Approach 2:
The patent effectively creates a composite surface structure on the copper foil through multi-component electrolyte formulations containing copper salts, wetting agents, brighteners, and stabilizers. This composite plating solution produces a surface that combines high conductivity with enhanced corrosion resistance, analogous to composite material principles
3Reliability
If copper foil conductivity is improved through surface treatment, then performance increases, but stability after heat treatment decreases
Solution Approach 1:
The patent applies preliminary action by pre-establishing a stable surface composition during electroplating that is resistant to heat-induced changes. The controlled water contact angle (60°-70°) and surface resistivity (2.4-2.7 mΩ/cm) are achieved through additive packages that form heat-stable surface structures, preventing degradation during subsequent battery manufacturing heat treatment processes (typically 80°C-150°C)
Solution Approach 2:
The patent uses parameter changes by optimizing the electrolyte temperature (20°C-40°C) and composition to create a surface structure that is thermally stable. The specific current density range (2-10 A/dm²) produces grain structures and surface morphologies that maintain their properties after heat treatment, ensuring composition stability
4Reliability
If water contact angle is optimized for conductivity, then surface resistivity improves, but manufacturing precision control becomes more difficult
Solution Approach 1:
The patent manages manufacturing precision by establishing a target range (60°-70° water contact angle) rather than a single value, and by using multiple controllable parameters (electrolyte temperature, current density, additive concentrations) to achieve this range. This multi-parameter approach provides process flexibility and robustness, making precise control achievable through standard industrial electroplating equipment
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 maintains high conductivity and productivity, enabling the production of secondary batteries with improved capacity and performance, as it prevents oxidation and corrosion, and ensures proper coating of active material layers.
Implementation Method 1
forming a copper film on a rotating anode drum by electrically connecting a cathode plate and the rotating anode drum, which are disposed to be spaced apart from each other in an electrolyte in an electrolytic bath
Implementation Method 2
electrically connecting a cathode plate and the rotating anode drum, which are disposed to be spaced apart from each other in an electrolyte in an electrolytic bath
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 a protective layer formed on the copper film, wherein the copper foil has a room temperature water contact angle in a range of 60° to 70°, and a room temperature surface resistivity in a range of 2.4 mΩ/cm to 2.7 mΩ/cm.