Battery Electrode Primer with Segmented Crosslinking
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Solution Overview
Problem
Existing electrochemical cell primers fail to provide simultaneous good adhesion and electrical contact between electroactive materials and conductive supports, leading to low discharge capacities and compatibility issues with electrolytes, as well as inadequate protection against corrosive effects.
Innovation Solution
The use of primer layers with varying degrees of crosslinking, including less than 30% crosslinked polymeric material, and the inclusion of hydroxyl functional groups in polymeric materials to enhance adhesion and electrical communication between the electroactive material, conductive support, and electrolyte, while minimizing corrosive effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If existing primers are used to provide adhesion between electroactive material and conductive support, then adhesion is improved, but electrical contact and discharge capacity deteriorate
Solution Approach 1:
The primer is divided into multiple layers with different crosslinking densities. The first primer layer has lower crosslinking density to provide good electrical contact with the electroactive material, while the second primer layer has higher crosslinking density to provide strong adhesion to the conductive support. This segmentation allows each layer to optimize its function without compromising the other.
Solution Approach 2:
Different regions of the primer structure are assigned different properties: the layer adjacent to the electroactive material has low crosslinking density for electrical conductivity, while the layer adjacent to the conductive support has high crosslinking density for mechanical adhesion. This local differentiation resolves the contradiction between electrical contact and adhesion strength.
2Strength
If crosslinked polymeric material is increased to improve adhesion, then adhesion is improved, but electrical conductivity and discharge capacity deteriorate
Solution Approach 1:
The primer structure is segmented into layers with varying crosslinking densities. The first layer maintains low crosslinking density to preserve electrical conductivity pathways, while the second layer uses high crosslinking density to maximize adhesion strength. This resolves the contradiction by spatially separating the conflicting requirements.
Solution Approach 2:
The primer is constructed as a composite structure combining materials with different crosslinking densities in specific layers. This composite approach allows the system to simultaneously achieve both high adhesion (through the highly crosslinked layer) and good electrical conductivity (through the lightly crosslinked layer).
3Reliability
If primer layers are added to improve adhesion and electrical contact, then discharge capacity is improved, but device complexity increases
Solution Approach 1:
The primer is segmented into two functional layers that can be applied in sequence using standard coating processes. While the structure is more complex than a single-layer primer, the segmentation enables simultaneous achievement of adhesion and electrical conductivity functions that a single layer cannot provide.
Solution Approach 2:
The multi-layer primer structure provides multiple functions within a single integrated component: the first layer provides electrical contact and adhesion to the electroactive material, while the second layer provides adhesion to the conductive support and structural stability. This multi-functionality justifies the increased structural complexity by delivering comprehensive performance improvement.
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 described primer arrangements achieve improved adhesion and electrical conductivity, leading to higher discharge capacities and reduced area specific resistance in electrochemical cells, with enhanced compatibility and protection against corrosive species.
Implementation Method 1
adhesion layers, also known as 'primers' or 'primer layers', deposited between the electroactive material and the conductive support can adhere to and provide electrical communication
Implementation Method 2
the first primer layer comprises less than 30% by weight of a crosslinked polymeric material
Data Source
Figure 1
AI summary
Primer arrangements that facilitate electrical conduction and adhesive connection between an electroactive material and a current collector are presented. In some embodiments, primer arrangements described herein include first and second primer layers. The first primer layer may be designed to provide good adhesion to a conductive support. In one particular embodiment, the first primer layer comprises a substantially uncrosslinked polymer having hydroxyl functional groups, e.g., polyvinyl alcohol. The materials used to form the second primer layer may be chosen such that the second primer layer adheres well to both the first primer layer and an electroactive layer. In certain embodiments including combinations of first and second primer layers, one or both of the first and second primer layers comprises less than 30% by weight of a crosslinked polymeric material. A primer including only a single layer of polymeric material is also provided.