Structured Current Collector for Battery Electrode Adhesion
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Solution Overview
Problem
In electrochemical systems, such as batteries and fuel cells, there is a challenge in achieving reproducible and stable electrodes due to poor adhesion of particle electrodes to current collectors, leading to increased electrical contact resistance and energy losses, particularly with metal foils like aluminum, which results in flaking and detachment of particles, causing local heating and reduced charging capacity.
Innovation Solution
The surface of the current collector is specifically structured to match the geometry of the particles, with particles being smaller than the indentations, allowing them to penetrate and adhere mechanically, reducing the need for binders and minimizing contact resistance, and using adhesion promoters to enhance the mechanical and chemical bonding between the current collector and particle electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If particles are coated onto a smooth current collector surface using conventional methods, then the coating process is simple, but the adhesion of particles to the current collector is poor, leading to flaking and detachment
Solution Approach 1:
The current collector surface is pre-structured with indentations or recesses before particle coating. This preliminary surface modification creates mechanical interlocking features that enhance particle adhesion, allowing particles to nestle into the depressions and form a more stable attachment, thereby reducing flaking and detachment during operation.
Solution Approach 2:
The invention creates a composite structure where the current collector surface geometry is specifically designed to match particle morphology. The combination of structured surface features and particulate material forms a mechanically interlocked composite system that improves adhesion strength beyond what either component could achieve alone.
2Strength
If binders are used to improve particle adhesion to the current collector, then adhesion is enhanced, but electronic conductivity is impeded and energy losses increase
Solution Approach 1:
The invention extracts or eliminates the binder component from the electrode structure by relying on mechanical interlocking through surface indentations. This removal of the insulating binder material allows direct electrical contact between particles and the current collector, maintaining high electronic conductivity while still achieving strong adhesion through the geometric interlocking mechanism.
Solution Approach 2:
The surface indentations act as an intermediary mechanical feature that mediates the connection between particles and the current collector. Instead of using a chemical binder as an intermediary, the physical geometry of the surface provides the mediating structure that enables both adhesion and electrical contact simultaneously.
3Strength
If particles are made smaller to improve adhesion, then contact area increases, but the need for binders increases to maintain structural integrity
Solution Approach 1:
The current collector surface is pre-modified with indentations of specific sizes and distributions that are tailored to accommodate smaller particles. This preliminary structuring allows even fine particles to find mechanical anchorage points, eliminating the need for binders to hold them in place while maintaining structural integrity of the electrode.
4Strength
If the current collector surface is structured to match particle geometry, then adhesion is significantly improved, but the manufacturing process becomes more complex
Solution Approach 1:
Surface structuring methods such as etching, embossing, or deposition of patterned layers are applied to the current collector before electrode assembly. These preliminary surface treatments create the required indentation patterns that will later provide mechanical interlocking, allowing the complex adhesion improvement to be achieved through a separate, optimized manufacturing step rather than during electrode fabrication.
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 improved mechanical stability and reduced electrical contact resistance, enhancing the performance and safety of electrochemical systems by ensuring better adhesion and conductivity, and eliminating the need for binders, which can impede electronic conductivity.
Implementation Method 1
The surface of the current collector is specifically structured to match the geometry of the particles, with particles being smaller than the indentations, allowing them to penetrate and adhere mechanically
Implementation Method 2
using adhesion promoters to enhance the mechanical and chemical bonding between the current collector and particle electrode
Data Source
Figure 1(a)~3
Figure 4~7
Figure 8~9
AI summary
The present invention relates to a composite material, comprising or consisting of a coating material having particles, and a base material, wherein the surface of the base material contains depressions, which lead to a reduced base material thickness at the location thereof, wherein the depressions are deviations from a smooth, even surface of the base material, characterised in that the geometric dimensions and/or forms of the particles and the depressions are similar or the same, such that one or more particles fit geometrically in the individual depressions, either in whole or in part, or have penetrated through the application of force and/or energy so adherently that said adhesion is based at least partially on mechanical forces between particles and base material. The invention further relates to electro-chemical systems, batteries, fuel cells, electrolysis cells or double layer capacitors, which contain said composite material in the form of electrodes, and to a method for producing said composite material.