Current Collector Joining Strength vs Energy Density
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Solution Overview
Problem
Conventional energy storage devices experience performance degradation due to the need for large forces and tools to embed current collectors into electrode assemblies, leading to increased active material non-applied portions that reduce energy density.
Innovation Solution
The energy storage device incorporates an electrode assembly and current collector with a thinner electrode connecting portion and convex portions that allow for a secure join with reduced force, minimizing the active material non-applied area and maintaining strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the current collector is embedded into the electrode assembly to firmly join them, then the joining strength is improved, but the active material non-applied portion increases and energy density decreases
Solution Approach 1:
The current collector is designed with varying wall thickness: a thicker first portion for structural support and electrical connection, and a thinner second portion at the joining area. This local variation in thickness allows the joining portion to be embedded into the electrode assembly with reduced force requirements, minimizing the active material non-applied portion while maintaining sufficient joining strength.
Solution Approach 2:
The current collector is segmented into functionally distinct portions: the first portion serves as the main body for electrical conduction and structural integrity, while the second portion is specifically designed for embedding into the electrode assembly. This segmentation allows each portion to be optimized for its specific function, reducing the overall embedding force needed while maintaining joining strength.
2Strength
If large force is applied to embed the current collector into the electrode assembly, then the joining strength is improved, but the active material non-applied area increases
Solution Approach 1:
The current collector features a localized thin wall thickness portion at the joining area, which requires smaller embedding force. This reduces the impact area on the electrode assembly, thereby minimizing the active material non-applied area while still achieving sufficient joining strength through the convex portion engagement.
Solution Approach 2:
The wall thickness parameter of the current collector is changed at the joining portion, creating a thin wall thickness portion that reduces the embedding force requirement. This parameter change allows for smaller force application during embedding, which in turn reduces the active material non-applied area while maintaining adequate joining strength.
3Force
If the wall thickness of the electrode connecting portion is reduced, then the embedding force is reduced and active material non-applied area is minimized, but the strength of the current collector may be compromised
Solution Approach 1:
The current collector employs different wall thicknesses in different locations: the first portion maintains sufficient thickness for structural strength and electrical conductivity, while the second portion at the joining area has reduced thickness to minimize embedding force. This local quality differentiation resolves the contradiction between reducing embedding force and maintaining overall strength.
Solution Approach 2:
The current collector is divided into segments with different thickness characteristics. The first portion serves as the strong main body, while the second portion is optimized for low-force embedding. The convex portion is strategically positioned to provide mechanical interlocking that compensates for the reduced thickness, maintaining joining strength without compromising the overall structural integrity.
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 configuration enhances the energy storage device's performance by reducing the active material non-applied area and maintaining strength, thereby suppressing performance degradation while firmly joining the electrode assembly and current collector.
Implementation Method 1
Either one of the second portion or the electrode assembly includes a first convex portion projecting toward another of the second portion and the electrode assembly in a joined portion
Data Source
AI summary
An energy storage device including: an electrode assembly and a positive electrode current collector, wherein the positive electrode current collector includes an electrode connecting portion connected to the electrode assembly, the electrode connecting portion includes a first portion and a second portion which has a smaller wall thickness than the first portion and is joined to the electrode assembly, and either one of the second portion or the electrode assembly includes a first convex portion projecting toward the other in a joined portion.