Electrolytic Copper Foil Grain Control for Battery Current Collectors
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Solution Overview
Problem
Existing electrolytic copper foils struggle to meet the desired physical properties required for use as current collectors in secondary batteries, particularly in lithium secondary batteries, due to limitations in elongation, electrical conductivity, and manufacturing complexity, which are not adequately addressed by conventional preparation processes.
Innovation Solution
The electrolytic copper foil is treated to enhance grain deformation selectively in a specific direction and increase average grain size, achieving a grain rate (G rate) of 50% or more, with improved electrical conductivity and elongation, and optionally includes an anti-corrosion layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolytic copper foil preparation process is used, then manufacturing process is simple, but physical properties (elongation and electrical conductivity) are insufficient for secondary battery applications
Solution Approach 1:
The patent applies preliminary action by controlling the grain structure and orientation during the electrolytic copper deposition process itself. Specific parameters such as current density, electrolyte composition, and deposition conditions are optimized in advance to produce copper foil with predetermined grain characteristics (average grain size of 3-10 μm and specific orientation distribution), eliminating the need for subsequent surface treatments or grain modification processes.
Solution Approach 2:
The patent employs parameter changes by systematically adjusting electrolytic deposition parameters including current density (10-50 A/dm²), electrolyte temperature (20-60°C), copper ion concentration (50-150 g/L), and deposition time to achieve the desired grain structure. These parameter optimizations directly produce copper foil with improved elongation (≥10%) and electrical conductivity (≥40 MS/m) without adding process complexity.
2Reliability
If grain size is increased to improve electrical conductivity, then electrical conductivity improves, but tensile strength decreases
Solution Approach 1:
The patent applies local quality by creating a non-uniform grain structure where larger grains (3-10 μm) are strategically distributed to enhance electrical conductivity in specific regions, while maintaining adequate tensile strength through controlled grain boundaries and orientation. The grain structure is optimized to have specific orientations that simultaneously improve conductivity pathways and maintain mechanical integrity.
Solution Approach 2:
The patent effectively creates a composite microstructure within the copper foil by combining grains of different sizes and orientations. The grain structure consists of a matrix of smaller grains with embedded larger grains, creating a hierarchical composite structure that leverages the high conductivity of larger grains while the finer grain matrix provides mechanical strength and ductility support.
3Reliability
If separate surface treatment is performed to improve physical properties, then elongation and conductivity improve, but manufacturing complexity and cost increase
Solution Approach 1:
The patent merges the grain structure control and surface property enhancement into a single integrated electrolytic deposition process. By optimizing deposition parameters such as current density distribution, electrolyte flow patterns, and temperature gradients during electrodeposition, the process simultaneously achieves desired grain morphology and superior surface properties, eliminating the need for separate surface treatment operations.
Solution Approach 2:
The electrolytic copper deposition process performs self-service by automatically generating the desired grain structure and surface properties through controlled electrochemical reactions. The electric field distribution, ion transport, and deposition kinetics work together to spontaneously form copper foil with optimized grain characteristics (3-10 μm average size, specific orientation) and improved surface quality, without requiring external intervention or additional processing steps.
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 treated copper foil maintains quality reliability and exhibits excellent performance as a current collector, enhancing electrical conductivity and elongation while reducing tensile strength, thus supporting stable battery operation.
Implementation Method 1
after heat treatment at 200° C. for 1 hour
Implementation Method 2
increase in shape deformation of grains selective to a specific direction and an increase in an average grain size after heat treatment
Implementation Method 3
an electrodeposited copper is precipitated on a drum surface by applying a direct current between an anode (e.g., a positive electrode) and a rotating cathode drum (e.g., a negative electrode) immersed in the electrolyte
Data Source
AI summary
An electrolytic copper foil having improved elongation and electrical conductivity is disclosed. The improved elongation and electrical conductivity are due to an increase in shape deformation of grains selective to a specific direction and an increase in an average grain size after heat treatment. An electrode for a secondary battery including the electrolytic copper foil, and a secondary battery including the electrode are disclosed.