Assembled Cell Spacer Design for Battery Positioning and Stress Control
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Solution Overview
Problem
Existing secondary battery assemblies face challenges in maintaining accurate positioning and preventing stress concentration and expansion of the battery container, especially in high-vibration environments like electric vehicles, due to the lack of effective fixation at the cell case ends.
Innovation Solution
The solution involves an assembled cell design with rectangular secondary batteries laminated in a thickness direction, utilizing spacers with contact parts, facing parts, and inclined surfaces to stabilize and compress the battery container, enhancing positioning accuracy and preventing stress concentration and expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the end part of the cell case is not fixed, then the cell can avoid stress concentration, but the cell positioning accuracy deteriorates due to movement from vibration
Solution Approach 1:
The spacer is divided into three functional segments: contact part (for positioning), inclined surface (for stress distribution), and facing part (for expansion prevention). This segmentation allows each region to perform its specific function optimally without compromising other requirements
Solution Approach 2:
Different regions of the spacer are designed with different geometries and functions: the contact part has a specific shape for positioning accuracy, the inclined surface gradually transitions to distribute stress, and the facing part provides expansion restraint. This local differentiation resolves the contradiction by providing different mechanical properties at different locations
2Manufacturing precision
If the cell case is held by adding pressure on the end part, then positioning accuracy is improved, but stress concentration occurs on the cell case
Solution Approach 1:
The inclined surface is designed to gradually transition the compression force from the contact part to the facing part before it reaches the cell case. This preliminary action of force distribution prevents sudden stress concentration at any single point on the cell case
Solution Approach 2:
The inclined surface acts as a cushioning element that softens and distributes the compressive force before it is transmitted to the cell case. This beforehand cushioning prevents stress concentration while maintaining positioning accuracy
3Stability of the object's composition
If the pressed surface is compressed to prevent expansion, then battery container expansion is suppressed, but positioning accuracy and stress distribution are compromised
Solution Approach 1:
The spacer's segmented design allows the facing part to specifically target expansion suppression at the width direction intermediate region, while the contact part independently handles positioning at the end regions. This segmentation enables simultaneous achievement of both functions without compromise
Solution Approach 2:
The facing part is specifically designed to face the width direction intermediate region where expansion occurs, providing localized compression exactly where needed. This local quality approach prevents expansion without affecting positioning accuracy at other regions
Data Source
AI summary
An assembled cell is formed by laminating a plurality of rectangular secondary batteries in a thickness direction and interposing a spacer between the rectangular secondary batteries. The rectangular secondary battery includes an electrode group in which positive and negative electrodes are wound, and the electrode group is housed in the battery container formed in a flat box shape. The spacer includes a contact part which contacts with a width direction end region of a wide side surface of the battery container, a facing part which faces a width direction intermediate region of the wide side surface, and an inclined surface which is adjacent to both ends of the facing part in a width direction of the wide side surface. The inclined surface is inclined such that a thickness of the spacer becomes asymptotically smaller in a direction toward the width direction intermediate region from the width direction end region.