Aluminum Alloy Foil Strength Retention After Battery Drying
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Solution Overview
Problem
Aluminum alloy foils used for lithium-ion secondary battery electrode current collectors experience a decrease in strength due to heat treatment during the drying process, leading to potential ruptures and reduced adhesion of the active material, which affects battery capacity.
Innovation Solution
The development of an aluminum alloy foil with specific compositions (0.1-0.5% Fe, 0.01-0.5% Si, 0.01-0.2% Cu, 0.01-0.5% Mn) and optimized temperature conditions during homogenization and hot rolling, which maintains high tensile strength after heat treatment, preventing center buckling and peeling of the active material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat treatment is carried out at 100 to 200°C during drying after active material coating, then the active material layer is properly dried, but the strength of aluminum alloy foil decreases making it likely to generate center buckle during press working
Solution Approach 1:
The patent applies parameter changes by carefully controlling the composition parameters (Fe: 0.03-0.5 mass%, Si: 0.03-0.5 mass%, Cu: 0.03-0.3 mass%, Mn: 0.03-0.5 mass%) and heat treatment parameters (temperature and time) to achieve the desired balance between drying effectiveness and strength retention. The specific compositional ranges and heat treatment conditions are optimized to minimize strength loss while ensuring proper drying.
Solution Approach 2:
The patent uses composite materials by creating an aluminum alloy foil with multiple alloying elements (Fe, Si, Cu, Mn) in specific proportions. This composite alloy structure provides both the necessary thermal stability during heat treatment and sufficient mechanical strength to prevent center buckling, resolving the contradiction between drying requirements and strength maintenance.
2Reliability
If heat treatment is carried out during drying after active material coating, then moisture is removed from the active material layer, but the aluminum alloy foil becomes more likely to rupture during slitting in post-process
Solution Approach 1:
The patent controls the compositional parameters and heat treatment parameters to maintain adequate strength after drying. The specific ranges for alloying elements and the optimized heat treatment conditions ensure that the foil retains sufficient strength to withstand slitting operations while still achieving effective moisture removal.
Solution Approach 2:
The multi-element aluminum alloy composite structure provides enhanced strength retention after heat treatment compared to pure aluminum or simpler alloys. The combination of Fe, Si, Cu, and Mn in controlled amounts creates a composite material that resists rupture during slitting while still allowing proper drying to occur.
3Reliability
If heat treatment is carried out during drying after active material coating, then the active material layer is dried, but the adhesion between active material and aluminum alloy foil surface decreases facilitating peeling during battery use
Solution Approach 1:
The patent optimizes the compositional parameters and heat treatment parameters to maintain adhesion quality. The specific compositional ranges and controlled heat treatment conditions prevent excessive oxidation or surface changes that would reduce adhesion, while still achieving effective drying of the active material layer.
Solution Approach 2:
The aluminum alloy composite with specific Fe, Si, Cu, and Mn content provides surface properties that maintain good adhesion between the active material and foil surface even after heat treatment. The composite structure ensures that the surface remains suitable for bonding while the interior undergoes proper drying.
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 provides an aluminum alloy foil with a tensile strength of 210 MPa or higher, preventing defects during press working and slitting, and maintaining high electrical conductivity, thus enhancing the durability and performance of lithium-ion secondary batteries.
Implementation Method 1
heat treatment is carried out at about 100 to 200° C. Accordingly, strength of aluminum is decreased by such heating
Implementation Method 2
by controlling the solid-solution and precipitation state conditions for their elements
Implementation Method 3
by controlling the solid-solution and precipitation state conditions for their elements
Data Source
AI summary
The present invention provides an aluminum alloy foil for electrode current collector, high in strength and superior in heat resistance after the active material coating/drying process of the manufacture of the battery, a manufacturing method thereof, and a lithium ion secondary battery. According to the present invention, an aluminum alloy foil for electrode current collector, including 0.1 to 0.5 mass % (hereinafter mass % is referred to as %) of Fe, 0.01 to 0.5% of Si, 0.01 to 0.2% of Cu, 0.01 to 0.5% of Mn, with the rest being Al and unavoidable impurities, wherein tensile strength of an aluminum alloy foil and a heat treatment selected from 24 hours at 100° C., 3 hours at 150° C., and 15 minutes at 200° C., is 210 MPa or higher, a manufacturing method thereof, and a lithium ion secondary battery are provided.