Secondary Battery Electrode Bonding With Fibrous Dry Binder
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Solution Overview
Problem
Existing methods for manufacturing electrodes for secondary batteries face challenges such as uneven binder distribution and difficulty in achieving strong joining of the electrode mixture sheet to the core, leading to issues like peeling and increased electrode plate penetration resistance.
Innovation Solution
A method involving a dry mixing process to create an electrode mixture with a solid content concentration of 100%, using a fibrous binder, and heat-pressing the mixture onto a core that softens at 200°C or lower, ensuring the binder remains fibrous and provides an anchor effect for strong adhesion without melting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a slurry including a binder dissolved in a solvent is used to manufacture an electrode, then adhesiveness between the mixture layer and core is achieved, but drying steps and equipment are required which reduce productivity
Solution Approach 1:
The invention extracts and removes the solvent from the conventional slurry-based manufacturing process. By using a dry mixture of binder powder and active material without any solvent, the process eliminates the drying step entirely while still achieving sufficient adhesiveness through the mechanical interlocking of binder fibers with the core surface.
Solution Approach 2:
The invention changes the physical state parameter of the binder from dissolved state (in slurry) to powdered state (in dry mixture). This parameter change allows the binder to function adhesively through fiber interlocking rather than through solution-based bonding, thereby eliminating the need for drying processes.
2Productivity
If a dry method without solvent is used to manufacture an electrode, then productivity is improved by eliminating drying steps, but joining strength between the electrode mixture sheet and core deteriorates leading to peeling
Solution Approach 1:
The invention applies local quality by using fibrous binder materials that create localized anchoring points throughout the mixture layer. These fiber structures provide concentrated adhesion zones that mechanically interlock with the core surface, achieving strong joining without requiring uniform solvent-based bonding across the entire interface.
Solution Approach 2:
The invention uses a composite structure combining binder powder with active material in a dry mixture. The fibrous binder components create a composite matrix that mechanically interlocks with the core, providing strong joining strength through physical interlocking rather than chemical bonding from dissolved binders.
3Strength
If hot-melt resin is used as a binder in dry method manufacturing, then joining between electrode mixture and core is achieved, but electrode plate penetration resistance increases largely
Solution Approach 1:
The invention uses binder powder in its original particulate or fibrous form without requiring it to undergo phase changes. This approach treats the binder as a structural component that provides mechanical interlocking throughout the mixture layer, rather than as a temporary bonding agent that must melt and solidify, thereby avoiding the formation of a dense resin layer that would increase penetration resistance.
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 achieves low electrode plate penetration resistance and high peeling strength by deeply embedding the active material in the core, maintaining the fibrous structure of the binder, and utilizing the core's softening property for effective joining.
Implementation Method 1
a core constituted with a metal foil that softens at 200° C. or lower
Implementation Method 2
the electrode mixture sheet includes an active material and a fibrous binder, and the active material is embedded in the core
Data Source
AI summary
This secondary battery electrode is provided with a core material configured from a metal foil that softens at less than or equal to 200° C., and an electrode mixture sheet which is bonded on the surface of the core material. The electrode mixture sheet includes an active material and a fibrous binder, and the active material bites into the core material, with the maximum bite depth at least 30% of the thickness of the core material. The fibrous binder may for example have polytetrafluoroethylene as the main component.