Cylindrical Battery Weld Geometry for Pressure-Resistant Sealing
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Solution Overview
Problem
Cylindrical batteries face issues with insufficient welding strength between the outer can and the sealing body, leading to potential rupture or ignition due to increased internal pressure from abnormal heat generation or physical impacts.
Innovation Solution
The cylindrical battery design includes a welded portion between the outer can and the sealing body, with a welding depth and area ratio optimized to ensure strong bonding, using laser welding techniques that adjust the optical axis and thermal energy application to prevent excessive deformation or evaporation, maintaining a safe and secure structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser welding is used to join the outer can and sealing body, then welding efficiency and precision are improved, but welding strength may be insufficient when internal pressure increases
Solution Approach 1:
The patent applies parameter changes by optimizing laser welding parameters including setting the welding speed between 5-20 mm/s, controlling laser power to achieve a welding depth ratio of 0.4-1.5, and adjusting the optical axis position. These parameter adjustments ensure that the welded portion has sufficient strength to withstand internal pressure while maintaining manufacturing precision through controlled laser application.
2Strength
If excessive thermal energy is applied during welding, then welding strength is improved, but deformation or electrolyte evaporation occurs
Solution Approach 1:
The patent controls thermal energy input by optimizing laser power and welding speed parameters. The welding speed is maintained between 5-20 mm/s and the laser power is adjusted to achieve a welding depth ratio (welding depth divided by the sum of outer can and sealing body thicknesses) of 0.4-1.5. This parameter optimization ensures sufficient welding strength while preventing excessive heat that would cause deformation or electrolyte evaporation.
Solution Approach 2:
The patent employs continuous laser welding along the circumferential direction to create a uniform welded portion. This continuous welding action ensures consistent heat distribution and melting throughout the joint, achieving uniform welding depth and strength while avoiding localized overheating that could cause deformation or evaporation.
3Strength
If welding depth is increased to improve welding strength, then resistance to internal pressure is improved, but thermal energy consumption and deformation risk increase
Solution Approach 1:
The patent optimizes the welding depth ratio (welding depth divided by the sum of outer can and sealing body thicknesses) to be between 0.4-1.5. This optimized depth range ensures sufficient welding strength to withstand internal pressure while avoiding excessive welding depth that would increase thermal energy consumption and deformation risk. The parameter is precisely controlled through laser power and welding speed adjustment.
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
The optimized welding process enhances the strength of the outer can and sealing body connection, preventing rupture and ensuring safety during high temperatures or over-discharge conditions, while avoiding excessive thermal energy application that could cause deformation or electrolyte evaporation.
Implementation Method 1
the outer can and the sealing body are welded using a method such as laser welding
Data Source
AI summary
A cylindrical battery includes a battery element, an outer can having a bottomed cylindrical shape with an opening on one side, a sealing body that seals the opening of the outer can, and a welded portion in which the outer can and the sealing body are welded. The outer can houses the battery element, and the welded portion extends in a first direction along a boundary between the outer can and the sealing body. A value obtained by dividing a maximum welding depth from an outermost surface of the welded portion in the first direction by a maximum thickness of a thickness of the outer can and a thickness of the sealing body is 0.4 or more and 1.5 or less.