Collector Plate Welding for Electrical Storage Devices
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Solution Overview
Problem
Existing welding methods for electrical storage devices, such as those described in Japanese Patent Applications JP 2001-256952 A, JP 2007-250442 A, and JP 2000-294222 A, face issues with internal short-circuits and increased I-V resistance due to heat distribution and tensile stress in the collector plate, making mass production unreliable and performance suboptimal.
Innovation Solution
A manufacturing method where an energy beam is applied to the boundary between the facing and projection portions of the collector plate, utilizing surface tension to form a molten pool without scattering, preventing internal short-circuits and tensile stress by controlling the angle and direction of the energy beam application, ensuring secure connection between the collector plate and the exposed portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inner peripheral surface of an arc-shaped projection portion is irradiated with a laser beam to melt the exposed portion, then welding is achieved, but heat accumulates at the tip of the projection portion causing through hole formation and internal short-circuit
Solution Approach 1:
The collector plate is divided into a facing portion and a projection portion, where the projection portion is positioned at the boundary. The energy beam is applied specifically to this boundary region, segmenting the welding zone to achieve controlled melting and prevent heat accumulation in any single location, thereby avoiding through hole formation.
Solution Approach 2:
The projection portion is given a specific local structure that differs from the facing portion. This local structural variation allows the projection portion to effectively control heat distribution during welding, preventing heat accumulation at the tip while ensuring proper welding at the boundary between the facing and projection portions.
2Reliability
If a ridge portion is pressed against the exposed portion and a laser beam is applied along its longitudinal direction, then welding is achieved, but the bottom part shrinks during cooling causing tensile stress and collector cutting
Solution Approach 1:
The collector plate structure is segmented into facing and projection portions with the projection portion located at the boundary. This segmentation allows controlled melting and cooling that prevents uniform shrinkage, thereby reducing tensile stress and preventing collector cutting during the welding process.
Solution Approach 2:
The projection portion is pre-formed on the collector plate before welding. This preliminary structural preparation ensures that during the welding and subsequent cooling process, the shrinkage occurs in a controlled manner that prevents tensile stress concentration and collector cutting.
3Reliability
If the projection portion is used for welding, then connection is achieved, but heat distribution is poor causing through hole formation and internal short-circuit
Solution Approach 1:
The welding zone is segmented by positioning the projection portion at the boundary between the facing and projection portions. The energy beam is applied to this boundary region, creating controlled heat distribution that prevents both heat accumulation and poor heat distribution, thereby avoiding through hole formation while ensuring welding quality.
4Productivity
If mass production is pursued using existing welding methods, then productivity increases, but reliability decreases due to internal short-circuit and performance degradation
Solution Approach 1:
The collector plate is segmented into facing and projection portions with the projection portion at the boundary. This structural segmentation enables reliable welding that prevents internal short-circuit, making the process suitable for mass production while maintaining high device reliability.
Solution Approach 2:
The projection portion provides local structural quality that ensures reliable welding and prevents heat-related defects. This local structural feature enables consistent welding quality across mass production, preventing reliability degradation while maintaining productivity.
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 method effectively prevents internal short-circuits and tensile stress, enhancing the performance and reliability of electrical storage devices by ensuring proper connection and reducing I-V resistance, thus enabling more efficient mass production.
Implementation Method 1
applying an energy beam to a boundary between the facing portion and the projection portion
Implementation Method 2
a surface tension works in a first direction and in a second direction on a molten material obtained by the application of the energy beam
Data Source
AI summary
An electrical storage device includes a polar plate and a collector plate. The polar plate includes a mixture layer and a collector. The collector includes an exposed portion. The exposed portion is exposed from the mixture layer in one end of the polar plate in a width direction. The collector plate includes a facing portion, a projection portion, and a corner portion. The facing portion is opposed to a tip end surface of the exposed portion. The projection portion extends from the facing portion so as to project toward the exposed portion relative to the facing portion. The corner portion is placed in a boundary between the facing portion and the projection portion. The collector plate is welded to the exposed portion in at least part of the corner portion.