Electrolytic Copper Foil Composition for Low-Temperature Battery Cycling
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Solution Overview
Problem
Electrolytic copper foils used in secondary batteries experience significant changes in physical properties, such as tensile strength and elongation, at low temperatures, leading to increased internal resistance and reduced battery life when exposed to cold conditions for extended periods.
Innovation Solution
Incorporating Total Organic Carbon (TOC) and metallic additives like cobalt, iron, and zinc into the copper electrolytic solution, with specific concentration ratios, to maintain consistent physical properties and minimize grain size variations, ensuring the copper foil's tensile strength and elongation remain above 80% of room temperature values even at -30°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrolytic copper foil is used in secondary batteries, then it provides good electrical conductivity and structural support, but its physical properties (tensile strength and elongation) change significantly at low temperatures, leading to increased internal resistance and reduced battery life
Solution Approach 1:
The patent applies parameter changes by controlling the grain size of the copper foil to be 10 μm or less through specific electrolysis conditions and post-treatment processes. This parameter control prevents abnormal grain growth at low temperatures, maintaining tensile strength and elongation properties, thereby resolving the contradiction between reliability and compositional stability.
Solution Approach 2:
The patent creates a composite structure by introducing specific crystal orientations and grain boundary characteristics into the copper foil. The controlled grain structure acts as a composite at the microstructural level, providing both electrical conductivity and mechanical stability at low temperatures, thus improving battery life while maintaining physical property stability.
2Duration of action of stationary object
If the copper foil is left at low temperature for a long time, then grain size and crystal structure change, but this causes deterioration of battery life
Solution Approach 1:
The patent applies preliminary action by pre-controlling the grain size to 10 μm or less and establishing specific crystal orientations before the battery is put into service. This preliminary structural preparation prevents subsequent grain growth and crystal structure changes during long-term low-temperature storage, thereby extending battery life while maintaining compositional stability.
Solution Approach 2:
The patent provides beforehand cushioning by creating a stable, fine-grained microstructure that acts as a buffer against thermal stress and prevents abnormal grain growth during low-temperature exposure. This pre-established structural resilience cushions the material against degradation, maintaining both duration of action and compositional stability.
3Adaptability or versatility
If internal resistance of the battery is kept constant at low temperatures, then battery performance varies less, but this requires maintaining physical property consistency of the copper foil which is difficult to achieve
Solution Approach 1:
The patent achieves adaptability by controlling critical parameters (grain size ≤10 μm, specific crystal orientations) during manufacturing. These parameter controls ensure the copper foil maintains consistent physical properties across temperature variations, resulting in stable battery performance without requiring complex operational adjustments.
Solution Approach 2:
The patent applies local quality by creating specific microstructural characteristics (fine grain size, preferred crystal orientations) in the copper foil that are optimized for low-temperature performance. This localized structural optimization enables the material to adapt to cold conditions while maintaining manufacturing feasibility through controlled electrolysis parameters.
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 solution effectively stabilizes the internal resistance of the anode and maintains excellent low-temperature properties, enhancing the battery's cycle characteristics and lifespan by preventing abnormal grain growth and maintaining physical property consistency.
Implementation Method 1
When a direct current flows between the cathode and the anode while rotating the cylindrical cathode, copper is electrodeposited on the cathode to enable continuous electrolytic copper foil production. The process of reducing copper ions into metal by the electrolysis method is referred to the foil manufacturing process.
Implementation Method 2
The electrolytic solution is composed of sulfuric acid and/or copper sulfate. When a direct current flows between the cathode and the anode
Data Source
AI summary
The present invention relates to an electrolytic copper foil for a secondary battery, having excellent physical properties at a low temperature, and a method for producing the electrolytic copper foil. The electrolytic copper foil for a secondary battery shows little change in the physical properties, such as tensile strength and elongation, of a copper foil even at a low temperature and thereby exhibits excellent cycle properties at the low temperature. The electrolytic copper foil for a secondary battery is produced from a plating solution, containing total organic carbon (TOC), cobalt, iron and zinc, by using a drum and coated with a cathode active material, wherein the ratio between the TOC, cobalt, iron and zinc contained in the electrolytic copper foil follows the following formula 1:TOC/(cobalt+iron+zinc)=1.0-1.2. [Formula 1]