Battery Cell Cap Structure for Uniform Electrode Pressure
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Solution Overview
Problem
Secondary batteries face challenges in minimizing the generation of lithium by-products during charging and discharging due to uneven pressure distribution on electrode assemblies, leading to defects and reduced performance.
Innovation Solution
A unit cell equipped with a cap member that uniformly controls pressure across the electrode assembly by using a cap member with specific surfaces and a contact member, made of insulating rubber or chemically resistant plastic, to cover the round portion of the electrode assembly, thereby minimizing lithium by-product generation and providing a space for gas capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple battery cells are disposed in devices to fulfill user demand, then the energy storage capacity is improved, but the device size increases and manufacturing complexity increases
Solution Approach 1:
The electrode assembly is divided into multiple electrode sheets (positive and negative electrodes) stacked alternately with separators, creating modular units that can be assembled into battery cells. This segmentation allows scalable energy storage capacity while maintaining manageable manufacturing processes for each cell unit.
2Productivity
If battery cells are manufactured in various structures to improve cell performance, then the energy storage capacity and efficiency are improved, but the manufacturing complexity and structural complexity increase
Solution Approach 1:
The cap member is provided with a specific structure including a contact member with a first space for gas capturing, and the electrode assembly has a round portion at one end. This local structural differentiation addresses specific functional needs (gas management, pressure distribution) without requiring complete redesign of the entire battery structure, thus improving performance with controlled complexity.
3Productivity
If pressure is applied to electrode assembly during charging and discharging, then the cell performance is improved, but uneven pressure distribution causes lithium by-product generation and reduces reliability
Solution Approach 1:
The cap member with the contact member and first space structure creates uniform pressure distribution across the electrode assembly during charging and discharging. This equipotential pressure application prevents localized stress concentrations that would otherwise generate lithium by-products, thereby maintaining high cell performance while ensuring battery reliability.
4Reliability
If a cap member is provided to control pressure distribution, then the pressure uniformity is improved and lithium by-product generation is reduced, but the device complexity increases
Solution Approach 1:
The cap member is designed to perform multiple functions: it provides uniform pressure distribution to the electrode assembly, captures gases through the first space, and maintains structural integrity. This multi-functionality reduces the need for separate components, thereby improving pressure uniformity and reliability without proportionally increasing overall device complexity.
Data Source
AI summary
A secondary battery includes a unit cell including an electrode assembly provided with a tab bundle and having a round portion, and a cap member in the vicinity of the round portion of the electrode assembly. The cap member includes a pair of first surfaces which are parallel to an upper surface and a lower surface of the electrode assembly, a pair of second surfaces which are parallel to both side surfaces of the electrode assembly, one third surface which connects the pair of first surfaces and the pair of second surfaces, and a contact member provided in an internal space formed by the pair of first surfaces, the pair of second surfaces, and the one third surface and in contact with the round portion of the electrode assembly. The third surface is provided with a through hole through which the tab bundle passes.