Secondary Battery Can Bottom Groove for Gas Release
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Solution Overview
Problem
Cylindrical lithium ion batteries face challenges in smoothly releasing gas during abnormal heat generation due to the positional relationship between the groove and the negative electrode current collector plate, leading to potential gas buildup and safety issues.
Innovation Solution
A secondary battery design featuring a strip-shaped positive and negative electrode configuration with a separator in between, where the active material non-covered portions of the electrodes are joined to the current collector plates and bent to form a flat surface with a groove, allowing for efficient gas release through a C-shaped groove in the battery can when internal pressure increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a groove is formed in the bottom portion of the battery can to enable gas discharge, then gas release capability is improved, but the positional relationship with the negative electrode current collector plate may prevent smooth gas release
Solution Approach 1:
The groove is designed with non-uniform thickness, featuring a thin portion and a thick portion. The thin portion is positioned to align with the plate-shaped portion of the negative electrode current collector plate, creating a localized weak point that preferentially opens during abnormal pressure events, ensuring reliable gas discharge while maintaining structural integrity elsewhere
Solution Approach 2:
The groove structure is pre-configured during manufacturing with specific thin and thick portions positioned at predetermined locations. This preliminary arrangement ensures that when abnormal heat generation occurs, the can bottom will open at the predetermined thin portion location rather than randomly, enabling controlled and reliable gas discharge
2Power
If the end surface of the electrode winding body is covered with the current collector plate to enable high current flow, then electrical performance is improved, but gas discharge is hindered
Solution Approach 1:
The groove is designed with spatially varying thickness, creating a thin portion that aligns with the current collector plate's plate-shaped portion. This localized thinning creates a preferential opening point that works in conjunction with the current collector plate structure, allowing both high current flow through the plate and controlled gas discharge through the aligned thin portion
Solution Approach 2:
The groove acts as an intermediary structure between the current collector plate and the battery can bottom. By positioning the groove's thin portion to align with the plate-shaped portion, it creates a coordinated system where the current collector plate maintains electrical performance while the groove enables gas discharge through their spatial relationship
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
Enables safe and efficient discharge of gas from the battery during abnormal heat generation by ensuring the can bottom opens at a weak point, preventing gas buildup and enhancing safety.
Implementation Method 1
when pressure inside the battery is increased by gas generated at the time of abnormal heat generation, the can bottom is opened (cleaved) starting from the groove having relatively low strength
Implementation Method 2
the can bottom is opened (cleaved) starting from the groove having relatively low strength
Data Source
AI summary
Disclosed is a secondary battery in which a negative electrode has a covered portion covered with a negative electrode active material covering portion and a negative electrode active material non-covered portion on a strip-shaped negative electrode foil, the negative electrode active material non-covered portion is joined to a negative electrode current collector plate at the other end portion of the electrode winding body, the electrode winding body has a flat surface formed by bending any one or both of a positive electrode active material non-covered portion and the negative electrode active material non-covered portion toward a central axis of the wound structure and overlapping the positive electrode active material non-covered portion and the negative electrode active material non-covered portion, and a first groove formed in the flat surface, at least one C-shaped second groove is included in a can bottom of a battery can.