Copper Foil Crystal Orientation for Battery Stability
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Solution Overview
Problem
The challenge is to produce copper foils that are free from curls, wrinkles, and tears during the manufacturing process, especially for thin film-type copper foils used in secondary batteries, as they are prone to defects such as curling and edge tears due to volume expansion of active materials during charge/discharge cycles.
Innovation Solution
The solution involves controlling the crystal orientation and residual stress of the copper layer in the copper foil by adjusting the texture coefficient ratio of specific crystal planes and applying a thin anticorrosive layer, along with a specific electrolyte composition and processing conditions to achieve a copper foil with a matte and shiny surface, reducing residual stress to 0.5-25 MPa and ensuring uniform surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of copper foil is decreased to increase active material content and battery capacity, then the capacity of secondary batteries increases, but curling is readily generated and defects such as tears or wrinkles occur
Solution Approach 1:
The patent controls the crystal orientation parameters of copper foil by adjusting the texture coefficient ratio TCR(220) to 5-30% and residual stress to 0.5-25 MPa. These parameter changes prevent curling while maintaining thin thickness (4-20 μm), enabling high active material content without defects during rolling and coating processes.
2Quantity of substance
If copper foil thickness is reduced to manufacture very thin film-type copper foils, then the amount of active material per area increases, but manufacturing becomes difficult due to curling
Solution Approach 1:
The patent modifies the physical parameters of copper foil by controlling crystal orientation (texture coefficient ratio TCR(220) of 5-30%) and residual stress (0.5-25 MPa). These changes eliminate curling, making it easy to manufacture very thin film-type copper foils (4-20 μm) with high active material content without defects.
3Quantity of substance
If copper foil is used to accommodate volumetric expansion of metal or composite active materials during charge/discharge, then high capacity is achieved, but the copper foil must withstand expansion stress without tearing
Solution Approach 1:
The patent changes the mechanical parameters of copper foil by controlling residual stress within 0.5-25 MPa and crystal orientation (texture coefficient ratio TCR(220) of 5-30%). These parameter changes enhance the strength and ductility of copper foil, enabling it to withstand the volumetric expansion stress of metal or composite active materials during charge/discharge cycles without tearing.
4Productivity
If copper foil is processed during rolling or coating of active materials by roll-to-roll process, then battery production efficiency increases, but edges of copper foil may be torn
Solution Approach 1:
The patent modifies the physical parameters of copper foil by controlling residual stress (0.5-25 MPa) and crystal orientation (texture coefficient ratio TCR(220) of 5-30%). These changes prevent edge tearing during high-speed rolling and coating processes, maintaining manufacturing precision while preserving high productivity in roll-to-roll battery production.
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
This approach effectively prevents curling, wrinkling, and tearing of the copper foil, enhancing its stability and workability, thereby improving the performance and lifespan of secondary batteries by maintaining uniform active material coating and accommodating high capacity requirements.
Implementation Method 1
the copper layer has a plurality of crystal planes, wherein a ratio TCR(220) of a texture coefficient (TC) of (220) crystal plane of the copper layer to a total of texture coefficients (TC) of (111), (200), (220) and (311) crystal planes of the copper layer is 5 to 30%
Implementation Method 2
a current density of 30 to 70 ASD is applied to an electrode plate and a rotary electrode drum spaced from each other in the electrolyte, to form a copper layer
Data Source
AI summary
Disclosed is a copper foil including a copper layer having a matte surface and a shiny surface, and an anticorrosive layer disposed on the copper layer, wherein the copper foil has a residual stress of 0.5 to 25 Mpa, based on absolute value, and the copper layer has a plurality of crystal planes, wherein a ratio [TCR (220)] of a texture coefficient (TC) of (220) crystal plane of the copper layer to a total of texture coefficients (TC) of (111), (200), (220) and (311) crystal planes of the copper layer is 5 to 30%.