Protective Copper Foil Coating for Battery Corrosion Resistance
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Solution Overview
Problem
Secondary batteries face issues with copper foil corrosion due to penetration of active materials and moisture, leading to reduced capacity retention and performance.
Innovation Solution
A copper foil with a protective layer composed of chromium, silane, or nitrogen compounds, achieving a moisture absorption rate of 0.1% or less, enhances corrosion resistance and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a copper foil is used as a negative electrode current collector in secondary batteries, then high energy density and charge/discharge capacity are achieved, but corrosion occurs due to penetration of active materials and moisture, leading to reduced capacity retention
Solution Approach 1:
A protective layer comprising a porous layer and a non-porous layer is introduced as an intermediary between the copper foil and the external environment. The porous layer allows lithium ion transport while the non-porous layer blocks moisture and active materials, preventing corrosion of the copper foil while maintaining high energy density and charge/discharge capacity
Solution Approach 2:
Thin film protective layers with controlled porosity are applied to the copper foil surface. These thin films provide corrosion protection against moisture and active materials while allowing ion transport, thereby maintaining the electrical conductivity and energy density characteristics of the copper foil
2Reliability
If a protective layer is added to prevent copper foil corrosion, then capacity retention and corrosion resistance are improved, but the structural complexity and manufacturing process are increased
Solution Approach 1:
The protective layer is segmented into two distinct functional layers: a porous layer for ion transport and a non-porous layer for environmental barrier. This segmentation allows each layer to perform its specific function optimally while together providing comprehensive corrosion protection
Solution Approach 2:
The protective layer is constructed as a composite structure combining porous and non-porous materials with different functions. The porous portion enables ion conductivity while the non-porous portion provides moisture and active material barrier, creating a composite protective system that addresses multiple requirements simultaneously
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 with a protective layer maintains excellent capacity retention and performance by preventing corrosion, ensuring high capacity and stability in secondary batteries.
Implementation Method 1
a protective layer which prevents penetration of active materials and moisture into the copper film
Implementation Method 2
the copper foil has a first moisture absorption rate of 0.1% or less
Data Source
AI summary
One embodiment of the present disclosure provides a copper foil including a copper film including 99.9 wt % or more of copper, and a protective layer disposed on the copper film, wherein the copper foil has a first moisture absorption rate of 0.1% or less. The first moisture absorption rate is expressed by Equation 1 below,first moisture absorption rate=(weight after 24-hour immersion-weight before immersion)/(weight after 24-hour immersion)×100 [Equation 1]wherein the immersion in Equation 1 refers to immersing a specimen in water at room temperature for 24 hours.