Cylindrical battery cell, and battery pack and vehicle including the same
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Solution Overview
Problem
Conventional cylindrical battery cells experience issues with high resistance and heat generation due to concentrated current flow in strip-shaped electrode tabs, leading to inefficiencies in electrical connections and increased risk of ignition during rapid charging, particularly when applied in larger form factors for electric vehicles.
Innovation Solution
The design includes a structure where both positive and negative electrode terminals are positioned adjacently, utilizing a terminal fastening member to secure a current collecting plate to the cell terminal, and optimizing the electrode assembly structure to enhance contact areas and minimize resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a strip-shaped electrode tab is used for current collection, then the structure is simple and easy to manufacture, but the current collection efficiency is poor due to large resistance and heat generation
Solution Approach 1:
The patent divides the current collection function into multiple components: the electrode tab is segmented into a connection portion and an extension portion, and further divided into multiple tabs (positive and negative) that are distributed around the cylindrical electrode assembly. This segmentation distributes the current flow path, reducing resistance and heat generation while maintaining manufacturing simplicity.
Solution Approach 2:
The patent transitions from a single-plane strip-shaped tab to a three-dimensional arrangement where multiple tabs extend radially outward from the cylindrical electrode assembly. The extension portions are positioned at different angular positions around the cylinder, utilizing spatial distribution to reduce current density concentration and improve current collection efficiency.
2Quantity of substance
If the form factor of cylindrical battery cell is increased to increase energy density, then the energy density increases, but heat generation around the electrode tab increases leading to ignition risk during rapid charging
Solution Approach 1:
The current collection system is segmented into multiple tabs instead of a single large tab. This divides the total current into multiple parallel paths, reducing the current density in each individual tab. The reduced current density decreases resistive heating (I²R losses) while maintaining the same total current collection capability, thus preventing ignition risk during rapid charging of large form factor cells.
Solution Approach 2:
The patent applies different structural characteristics to different parts of the electrode tab system. The connection portions are designed for strong electrical connection to the electrode, while the extension portions are designed for optimal spatial distribution and heat dissipation. This local optimization ensures efficient current collection while managing heat generation in critical areas.
3Power
If multiple battery cells are connected in series to achieve higher output voltage, then the output voltage increases, but the electrical wiring becomes complex causing inconvenience in assembling and maintenance
Solution Approach 1:
The patent combines the electrical connection functions into integrated terminal structures. The positive and negative electrode tabs are positioned and configured to facilitate direct series connections between cells, reducing the need for separate wiring harnesses and connection components. This merging of functions simplifies the overall electrical wiring architecture while maintaining high output voltage capability.
Data Source
AI summary
A cylindrical battery cell includes an electrode assembly having a first electrode tab with a first polarity and a second electrode tab with a second polarity; a battery can having an open portion formed at a lower end and a closed portion formed at an upper end, configured to accommodate the electrode assembly through the open portion, and electrically connected to the second electrode tab; a cell terminal electrically connected to the first electrode tab, exposed to an outside of the battery can through the closed portion of the battery can, and electrically insulated from the battery can; a first current collecting plate having a first surface and a second surface opposite to the first surface, wherein the first surface is coupled to the first electrode tab and the second surface is coupled to the cell terminal; and a terminal fastening member configured to mechanically fasten the cell terminal and the first current collecting plate.