Electrolytic Copper Foil Surface Morphology for Battery Adhesion
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Solution Overview
Problem
Lithium-ion batteries face shortened charge-discharge cycle life due to inadequate adhesion strength between the electrolytic copper foil and active materials, leading to premature peeling and detachment during charging and discharging.
Innovation Solution
The electrolytic copper foil is engineered with specific surface characteristics, including Kurtosis (Sku) ranging from 1.8 to 6.4, developed interfacial area ratio (Sdr) between 0.06% to 13%, and texture aspect ratio (Str) between 0.1 to 1, enhancing adhesion strength with active materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional electrolytic copper foil with standard surface characteristics is used, then manufacturing cost and production simplicity are maintained, but adhesion strength between copper foil and active material is insufficient leading to premature peeling during charge-discharge cycles
Solution Approach 1:
The patent applies parameter changes by precisely controlling three surface characteristic parameters (Sku, Sdr, Str) within specific ranges to optimize adhesion strength. This resolves the contradiction by transforming the surface properties through controlled parameter variation rather than complex structural modifications, achieving enhanced adhesion while maintaining manufacturing feasibility.
Solution Approach 2:
The patent creates a composite surface structure on the copper foil by combining specific roughness characteristics (Sku 2.5-6.4), developed interfacial area (Sdr 0.06-13%), and texture orientation (Str 0.1-1.0). This composite surface morphology acts as a mechanical interlocking structure that enhances adhesion strength without requiring additional coating materials or complex processing steps.
2Strength
If copper foil with enhanced surface roughness is used to improve adhesion, then adhesion strength increases, but charge-discharge cycle life is shortened due to excessive expansion and contraction stress
Solution Approach 1:
The patent optimizes the balance between adhesion and cycle life by precisely controlling the Sku parameter within 2.5-6.4 range. This specific parameter range provides sufficient surface roughness for mechanical interlocking while avoiding excessive roughness that would create stress concentration points during expansion-contraction cycles, thus extending battery lifespan.
Solution Approach 2:
The patent utilizes controlled surface curvature through the Str parameter (texture aspect ratio 0.1-1.0) to create rounded surface features rather than sharp peaks. This curvature distribution reduces stress concentration during lithium-ion insertion and extraction, preventing crack initiation while maintaining adequate adhesion strength for cycle life extension.
3Reliability
If copper foil with optimized surface characteristics is used, then adhesion strength and cycle life are improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent establishes specific parameter ranges (Sku 2.5-6.4, Sdr 0.06-13%, Str 0.1-1.0) that provide manufacturing tolerance windows. These ranges are designed to be achievable with conventional electrolytic copper foil production processes, balancing reliability improvement with manufacturing precision requirements without necessitating ultra-precise control systems.
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
These surface characteristics significantly improve the adhesion strength between the copper foil and active materials, thereby extending the charge-discharge cycle life of lithium-ion batteries beyond 800 cycles and enhancing their reliability and durability.
Implementation Method 1
an electrolytic copper foil, which comprises a drum side and a deposited side opposite the drum side
Data Source
AI summary
Provided are an electrolytic copper foil, an electrode comprising the same, and a lithium-ion battery comprising the same. The electrolytic copper foil comprises a drum side and a deposited side opposite each other. The drum side and the deposited side each have a Kurtosis (Sku) in a range of 1.8 to 6.4, a developed interfacial area ratio (Sdr) in a range of 0.06% to 13%, and a texture aspect ratio (Str) in a range of 0.1 to 1. With the surface morphology, the electrolytic copper foil has an improved adhesion strength with the active material, and thus improving the charge-discharge cycle life performance of the lithium-ion secondary battery.