CNT Undercoat Foil for Ultrasonic-Welded Low-Resistance Electrodes
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Solution Overview
Problem
Current methods for manufacturing energy storage devices, such as lithium-ion secondary batteries and electrical double-layer capacitors, face challenges in achieving low resistance and high productivity due to issues with ultrasonic welding of undercoat layers, particularly with carbon materials, leading to reduced versatility and increased complexity in current-collecting substrates.
Innovation Solution
The use of a carbon nanotube (CNT)-containing undercoat foil with a specific coating weight range (0.001 g/m² to 0.05 g/m²) on current-collecting substrates enables efficient ultrasonic welding and reduces resistance in energy storage devices, allowing for a simpler and more productive manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an undercoat layer is formed on the current-collecting substrate to strengthen adhesion and lower resistance, then adhesion strength and electrical conductivity are improved, but the complexity of the substrate increases and versatility decreases
Solution Approach 1:
The invention changes the material composition parameter of the undercoat layer by incorporating carbon nanotubes with specific physical properties (high aspect ratio, specific surface area within 10-1000 m²/g). This parameter change enables the undercoat layer to maintain adhesion strength while becoming ultrasonic-weldable, thus resolving the contradiction between reliability and versatility.
2Ease of manufacture
If the undercoat layer coating weight is increased to improve welding performance, then weldability is improved, but the resistance of the energy storage device increases
Solution Approach 1:
The invention changes the physical parameter of carbon nanotubes by selecting specific aspect ratios and surface areas, which fundamentally alters the welding characteristics. This allows achieving good ultrasonic welding performance at low coating weights (0.01-5 mg/m²), preventing the resistance increase that would occur with higher coating weights.
Solution Approach 2:
The invention creates a composite undercoat layer combining carbon nanotubes with other carbon materials or conductive polymers. This composite structure provides both ultrasonic welding capability and low electrical resistance, resolving the contradiction between ease of manufacture and reliability.
3Reliability
If conventional carbon materials are used in the undercoat layer, then adhesion is maintained, but ultrasonic welding with good reproducibility cannot be achieved
Solution Approach 1:
The invention fundamentally changes the physical parameters of carbon materials by specifying aspect ratios of 10-1000 and specific surface areas of 10-1000 m²/g. These parameter changes transform conventional carbon materials into ultrasonic-weldable materials while maintaining adhesion properties, thus resolving the contradiction between reliability and ease of manufacture.
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 results in a low-resistance energy storage device that can be efficiently manufactured using ultrasonic welding, enhancing both the performance and productivity of energy storage devices like lithium-ion secondary batteries and electrical double-layer capacitors.
Implementation Method 1
ultrasonic welding can be efficiently carried out on a region of the current-collecting substrate where a CNT-containing undercoat layer has been formed
Implementation Method 2
welding is carried out by applying ultrasonic vibrations
Implementation Method 3
lowering the resistance at the contact interface therebetween
Data Source
AI summary
This undercoat foil for an energy storage device electrode comprises a collector base plate, and an undercoat layer formed on at least one surface of the collector base plate, the undercoat layer containing carbon nanotubes, and the coating amount per collector base plate surface being 0.1 g/m2 or less. Since this undercoat foil can be effectively welded by ultrasound, the use thereof allows a low-resistance energy storage device and a simple and effective production method therefor to be provided.