Electrolytic Copper Foil Texture Control for Battery Life
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electrolytic copper foils used in lithium ion secondary batteries have high roughness on the matte side, leading to reduced tensile strength, elongation, and increased risk of fracture during charging-discharging cycles, which limits battery life.
Innovation Solution
An electrolytic copper foil with a shiny side and matte side having a roughness of less than 2 μm, where the sum of texture coefficients of the (220) and (311) surfaces is greater than 60% of the total, and the addition of acid-denatured polyvinyl alcohol to the copper sulfate electrolyte results in improved crystalline phase characteristics, reducing roughness difference and enhancing elongation and charging-discharging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional electrolytic copper foil is used with traditional crystalline phase composition, then the manufacturing process is simple, but the roughness of the matte side is high leading to reduced tensile strength and elongation
Solution Approach 1:
The patent changes the crystalline phase parameters by controlling the texture coefficients, specifically requiring the sum of texture coefficients of (220) and (311) surfaces to be greater than 60% of the total. This parameter change in crystalline structure leads to reduced roughness on the matte side while improving tensile strength and elongation properties
Solution Approach 2:
The patent creates a composite crystalline structure by promoting specific crystal orientations ((220) and (311) planes) in the copper foil. This composite approach to crystalline phase composition, where multiple crystal orientations work together, achieves both low roughness and high mechanical strength simultaneously
2Reliability
If conventional electrolytic copper foil is used, then the production process is straightforward, but the elongation is insufficient leading to increased fracture risk during battery cycles
Solution Approach 1:
The patent modifies the crystalline phase parameters by establishing specific texture coefficient ratios, where (220) and (311) orientations dominate. This parameter optimization improves elongation and fracture resistance without requiring complex manufacturing process changes, maintaining ease of production while enhancing reliability
3Productivity
If conventional electrolytic copper foil with high matte side roughness is used, then the manufacturing is simpler, but the charging-discharging efficiency is reduced and battery life is limited
Solution Approach 1:
The patent optimizes the crystalline phase parameters by controlling texture coefficients to exceed 60% for (220) and (311) surfaces. This parameter optimization reduces surface roughness on the matte side, which directly improves charging-discharging efficiency and extends battery cycle life from conventional limits to over 2000-6000 cycles
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 electrolytic copper foil exhibits increased elongation, reduced weight resistivity, and improved charging-discharging efficiency, with no fractures observed after 2000 to 6000 cycles, significantly extending battery life.
Implementation Method 1
using a titanium drum as a cathode, applying direct current between two electrodes to electrodeposit copper ions from the electrolyte on the titanium drum
Implementation Method 2
the crystalline phase of the electrolytic copper foil is changed by adding an organic additive, such as glue with a small molecular weight (e.g. gelatin), hydroxyethyl cellulose (HEC), or polyethylene glycol (PEG), and adding a sulfur-containing compound such as sodium 3-mercapto-1-propanesulfonate (MPS) or bis-(3-sodiumsulfopropyl disulfide (SPS) with the effect of reducing (refining) the size of the crystals
Data Source
AI summary
An electrolytic copper foil, which is particularly suitable for the application of a lithium ion secondary battery, has a shiny side and a matte side with a roughness of less than 2 μm. Based on the total sum of the texture coefficients of a (111) surface, a (200) surface, a (220) surface and a (311) surface of the electrolytic copper foil, the sum of the texture coefficients of the (220) surface and the (311) surface of the electrolytic copper foil is greater than 60%.