Energy Storage Device Electrode Adhesion Control
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries experience a decrease in power due to repetitive charge-discharge in high-temperature environments, primarily attributed to increased internal resistance caused by peeling of the active material layer from the conductive layer.
Innovation Solution
The energy storage device incorporates an active material layer with a particulate active material and a conductive layer containing a conduction aid, where the average secondary particle diameter of the active material is between 2.5 μm and 6.0 μm, and the surface roughness of the conductive layer is between 0.17 μm and 0.50 μm, ensuring sufficient contact and adhesion between the layers, thereby suppressing the increase in internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the active material layer is formed with fine particles to increase surface area, then the power density improves, but the adhesion to the conductive layer deteriorates causing peeling during charge-discharge cycles
Solution Approach 1:
The invention changes the particle size parameter of the active material to a specific range (2.5-6.0 μm) that balances surface area for power density with adhesion stability. This parameter optimization prevents peeling during charge-discharge cycles while maintaining high power output.
Solution Approach 2:
The invention applies different surface treatments to different regions of the conductive layer. The surface roughness is controlled to be 0.17-0.50 μm to create optimal local adhesion zones, while maintaining smooth areas for electrical conductivity. This local differentiation resolves the contradiction between adhesion and conductivity.
2Power
If the conductive layer surface is made smoother to improve electrical conductivity, then the electron transport improves, but the contact area with active material decreases reducing adhesion
Solution Approach 1:
The invention optimizes the surface roughness parameter of the conductive layer to a specific range (0.17-0.50 μm). This parameter change creates a balance where the surface is smooth enough for good electrical conductivity but has sufficient micro-roughness to provide adequate contact area and adhesion with the active material layer.
3Speed
If the active material particles are made smaller to increase reaction sites, then the charge-discharge rate improves, but the internal resistance increases due to poor layer contact
Solution Approach 1:
The invention changes the particle size parameter to an optimal range (2.5-6.0 μm) that provides sufficient reaction sites for high charge-discharge rates while maintaining good layer contact to prevent increased internal resistance. This parameter optimization resolves the contradiction between reaction speed and electrical resistance.
Data Source
AI summary
An energy storage device is provided in which a decrease in power caused by repetitive charge-discharge in a high-temperature environment is suppressed. In the present embodiment, an energy storage device and a method for manufacturing the energy storage device are provided, the energy storage device including an electrode which includes: an active material layer including a particulate active material; and a conductive layer layered on the active material layer and including a conduction aid. An average secondary particle diameter of the active material is 2.5 μm or more and 6.0 μm or less. A surface roughness Ra of the conductive layer on a side on the active material layer is 0.17 μm or more and 0.50 μm or less.