Secondary Battery Electrode Co-Coating for Wrinkle-Free Calendering
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Solution Overview
Problem
Calendering processes in energy storage device manufacturing often result in wrinkles due to non-uniform thickness and compressibility of coated materials on foils, leading to reduced performance and increased costs when attempting to coat entire foils with active material.
Innovation Solution
Applying a sacrificial alternate material to uncoated areas of the foil, selected to match the compressibility of the active material, ensures uniform pressure during calendering, minimizing wrinkles. This alternate material can be later removed using methods like laser ablation or brushing with vacuum collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If only partial areas of the foil are coated with active material, then material cost is reduced, but wrinkles occur during calendering due to non-uniform pressure
Solution Approach 1:
A sacrificial material is introduced as an intermediary substance applied to uncoated areas of the foil. This sacrificial material acts as a mediator that absorbs excess pressure during calendering, preventing the foil from stretching unevenly and forming wrinkles. The sacrificial material is subsequently removed after serving its protective function during the calendering process.
Solution Approach 2:
The sacrificial material functions as a temporary, disposable component that is applied to the foil, serves its pressure-absorbing purpose during calendering, and is then removed. This disposable approach allows the use of inexpensive materials that can be discarded after a single use, enabling partial coating with expensive active material without compromising calendering quality.
2Adaptability or versatility
If different materials with different compressibilities are coated on the foil, then functional diversity is improved, but wrinkles occur due to differential stretching during calendering
Solution Approach 1:
The sacrificial material serves as a mediator between the differently compressible coated materials and the calendering pressure. It compensates for the compressibility differences by absorbing excess pressure in areas where materials are more easily compressed, thereby preventing differential stretching and wrinkle formation while allowing diverse functional materials to be used.
3Manufacturing precision
If the entire foil is coated with active material to ensure uniform pressure, then wrinkle formation is reduced, but material cost increases
Solution Approach 1:
The sacrificial material acts as a substitute intermediary applied to uncoated areas, providing the pressure-absorbing function that would otherwise require active material coverage. This allows uniform pressure distribution during calendering to be achieved while using active material only where functionally necessary, significantly reducing material costs.
Solution Approach 2:
By using inexpensive sacrificial material as a temporary placeholder in uncoated areas, the need to cover the entire foil with expensive active material is eliminated. The sacrificial material performs the pressure-absorbing function during calendering and is then removed, enabling cost-effective partial coating strategies.
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 approach achieves more even pressure distribution during calendering, significantly reducing wrinkles and enhancing the homogeneity and performance of energy storage devices, while also reducing material costs by not requiring full coverage of active material.
Implementation Method 1
The alternate material may be removed using laser ablation
Data Source
AI summary
Systems and methods are provided herein for applying sacrificial material to otherwise uncoated areas of a foil to provide uniform pressure during calendering. For example, one or more portions of a foil may be coated with an active material while other portions of the foil may be coated with an appropriately selected alternate material. After the active material and the alternate material are applied to the foil, the foil may be dried and then calendered. During calendering, the compressive force of the rollers can cause the portion of the foil coated in the active material to stretch a similar amount to the portions of the foil coated in the alternate material. The resulting calendered web has minimal wrinkles due to the similarity of the stretching of the foil coated in the active material and the foil coated in the alternate material.