Multilayer Electrode Films for Adhesion and Thick Electrode Stability
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Solution Overview
Problem
Existing electrode films in energy storage devices face mechanical limitations due to poor adhesion between active layers and current collectors, and cohesion between active materials and binders, leading to reduced performance in power delivery and energy storage capacity, as well as mechanical degradation from volumetric changes in active materials.
Innovation Solution
The development of multilayer electrode films comprising two or more self-supporting active layers with different compositions, which are stacked and laminated to a current collector without a separate adhesive layer, enhancing adhesion and cohesion, and allowing for improved mechanical properties and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-layer electrode film is used, then the fabrication process is simple, but the adhesion between active layers and current collector is poor
Solution Approach 1:
The electrode film is divided into multiple layers (first active layer, second active layer, third active layer) with different compositions. Each layer is optimized for specific functions: the first layer provides good adhesion to the current collector, the second layer contains the main active material, and the third layer provides protective and adhesive properties. This segmentation resolves the contradiction by maintaining fabrication simplicity while significantly improving adhesion through compositional differentiation.
Solution Approach 2:
Different regions of the electrode film have different compositions tailored to local requirements. The first active layer near the current collector has composition optimized for adhesion, the second active layer has composition optimized for electrochemical performance, and the third active layer has composition optimized for protection and interfacial adhesion. This local quality approach allows each region to perform its specific function optimally.
2Device complexity
If a single-layer electrode film is used, then the structure is simple, but the cohesion between active materials and binders is poor
Solution Approach 1:
The electrode is segmented into three distinct active layers, each with optimized binder and active material ratios. The first layer has binder composition optimized for current collector adhesion, the second layer has composition optimized for active material cohesion, and the third layer has composition optimized for surface stability. This segmentation improves cohesion without requiring a single complex homogeneous structure.
Solution Approach 2:
The electrode uses composite material composition across different layers, combining different ratios of active materials, binders, and conductive additives in each layer. This composite approach allows optimization of cohesion in the second layer while maintaining adhesion in the first and third layers, resolving the contradiction between structural simplicity and cohesive reliability.
3Reliability
If adhesive layers are added between active layers, then the adhesion is improved, but the device complexity increases
Solution Approach 1:
The first and third active layers serve dual functions: they contain electrochemically active materials for energy storage while simultaneously providing adhesive functions between layers and between the electrode and current collector. This multi-functionality eliminates the need for separate adhesive layers, maintaining device simplicity while improving adhesion reliability.
Solution Approach 2:
The first and third active layers are designed with compositions that enable them to self-adhere to adjacent layers and to the current collector without requiring external adhesive materials. The binder composition in these layers is specifically optimized to provide self-adhesive properties, allowing the structure to serve its own adhesion needs.
4Quantity of substance
If the electrode film thickness is increased, then the energy storage capacity is improved, but the mechanical degradation from volumetric changes is worsened
Solution Approach 1:
The thick electrode film is segmented into three thinner active layers, each with manageable thickness that experiences reduced volumetric stress during charge-discharge cycles. The first layer acts as a buffer near the current collector, the second layer contains the bulk active material, and the third layer provides protective coverage. This segmentation allows increased total thickness for higher capacity while maintaining mechanical stability through reduced individual layer stress.
Solution Approach 2:
Different layers have compositions optimized for different mechanical requirements. The first layer has composition optimized for mechanical stability and adhesion to handle volumetric changes near the current collector interface. The second layer has composition optimized for maximum energy density. The third layer has composition optimized for surface stability and protection. This local quality differentiation allows the overall structure to accommodate volumetric changes better.
Data Source
AI summary
Provided herein are energy storage device electrode films comprising multiple active layers, and methods of forming such multiple active layer energy storage device electrode films. Each active layer may be a self-supporting active layer comprising a binder and an active material. The binder and/or active material may be the same or different as any other active layer. The active layers may be stacked to form an electrode film, and the electrode film may be laminated with a current collector to form an electrode.