Foamed Metal Negative Electrode Plate Joining Without Cold Solder Joints
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Solution Overview
Problem
The existing methods for preparing negative electrode plates with foamed metal current collectors face challenges such as low mechanical strength, poor electrical conductivity, high self-discharge rates, and imbalanced voltage due to the high porosity and low mechanical strength of foamed metals, leading to difficulties in manufacturing and performance issues in secondary batteries.
Innovation Solution
A method involving roll welding of a metal foil to a foamed metal current collector with specific porosity levels, using ultrasonic welding with controlled parameters to form a tab, which enhances mechanical strength and electrical conductivity by avoiding issues like cold solder joints and over-melting, thereby improving the cycle performance of the battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If foamed metal with high porosity is used as current collector, then heat dissipation and lithium deposition suppression are improved, but mechanical strength deteriorates
Solution Approach 1:
The patent uses a composite structure consisting of a metal foil layer and a foamed metal layer. The metal foil layer provides mechanical strength while the foamed metal layer provides heat dissipation and lithium deposition suppression. This composite structure resolves the contradiction by combining materials with complementary properties.
2Ease of manufacture
If traditional welding methods are used to connect metal foil to foamed metal, then connection is achieved, but manufacturing defects occur
Solution Approach 1:
The patent replaces traditional thermal welding methods with ultrasonic welding. This mechanical vibration-based welding method avoids the thermal damage, over-melting, and wrinkling issues associated with conventional welding, while still achieving strong connections between the metal foil and foamed metal layers.
3Ease of manufacture
If conventional welding parameters are used, then welding is achieved, but foamed metal damage occurs
Solution Approach 1:
Ultrasonic welding uses mechanical vibration energy instead of thermal energy, allowing welding at lower temperatures that do not damage the delicate foamed metal structure. This avoids over-melting and structural collapse while achieving adequate weld strength.
Solution Approach 2:
The patent optimizes ultrasonic welding parameters including power density (2.0 to 28 W/cm²), pressure (0.1 to 1.0 MPa), and amplitude (10 to 50 μm) to achieve effective welding without damaging the foamed metal. These controlled parameters ensure proper bonding while preserving the foamed metal's structural integrity.
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 method effectively improves the mechanical properties and electrical conductivity of the negative electrode plate, leading to enhanced cycle performance and reduced manufacturing costs, resulting in a more efficient and durable secondary battery.
Implementation Method 1
roll welding, where the roll welding is ultrasonic welding
Data Source
AI summary
This application provides a negative electrode plate and a method for preparing same. In the method, a metal foil is connected to a foamed metal current collector by roll welding, so as to form the negative electrode plate. The metal foil forms a tab of the negative electrode plate, and the foamed metal current collector includes a foamed metal layer of a porosity of 60% to 99%, and optionally 80% to 85%. The method reduces or avoids flying metal chips and cold solder joints, and improves mechanical strength and electrical conductivity of the electrode plate. This application also provides a negative electrode plate prepared by the method, a secondary battery containing the negative electrode plate, and an electrical device.