Battery Pack Beam Structure for Controlled Cell Expansion
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Solution Overview
Problem
Battery packs in vehicles experience structural stress due to periodic expansion of lithium-ion batteries during charge-discharge cycles, leading to excessive pressure on the first side wall, which can cause lithium plating and reduce the service life if not properly restrained.
Innovation Solution
A battery pack design featuring a non-detachable first beam and a detachable second beam at the ends of the battery module, with the second beam allowing for controlled expansion restraint without excessive force on the electrode assembly, enhancing safety and prolonging the battery pack's service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a hard case battery with square structure is used, then the battery pack structure is simplified, but the expansion force generates excessive pressure on the first side wall and end plates
Solution Approach 1:
The battery pack structure is segmented into multiple independent beams (first beam, second beam, third beam, fourth beam) that collectively support the battery module. Each beam is positioned at different locations and oriented in different directions to distribute the expansion forces uniformly across the battery module, preventing excessive pressure concentration on any single side wall or end plate.
Solution Approach 2:
Different beams are designed with different structural characteristics and positioning to address local stress requirements. The first and second beams extend along the first direction to support the first side wall, while the third and fourth beams extend along the second direction to support the end plates. This localized structural quality ensures optimal force distribution matching the specific expansion patterns of the battery cells.
2Stability of the object's composition
If rigid restraint structure is used to resist expansion force, then structural stability is improved, but lithium plating occurs due to excessive force on electrode assembly
Solution Approach 1:
The beam structure is designed with appropriate spacing and flexible connection characteristics to provide cushioning during battery expansion. The beams are positioned to create a restraint framework that allows controlled expansion movement while preventing excessive force transmission to the electrode assembly, thereby cushioning the battery cells from damaging stresses that would cause lithium plating.
Solution Approach 2:
The restraint structure incorporates dynamic characteristics through the strategic positioning and spacing of multiple beams. The structure allows for controlled movement and deformation during battery expansion cycles, adapting to the changing volume of the battery cells while maintaining structural integrity. This dynamic restraint prevents both excessive rigidity (causing lithium plating) and excessive flexibility (compromising structural stability).
Data Source
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AI summary
The disclosure provides a battery pack and a vehicle. The battery pack includes: a housing including a housing bottom wall and a housing side wall, wherein the housing bottom wall and the housing side wall form an accommodating space; a battery module disposed in the accommodating space and including a plurality of batteries, wherein a case side wall of the battery includes two first side walls oppositely disposed along a first direction and two second side walls oppositely disposed along a second direction, an area of the first side wall is larger than an area of the second side wall, and the first direction and the second direction are both parallel to the housing bottom wall and perpendicular to each other; and a frame structure disposed in the accommodating space for limiting a position of the battery module, wherein the frame structure includes a first beam and a second beam respectively located at two ends of the battery module along the first direction, the first beam and the second beam extend along the second direction and are disposed opposite to the first side wall along the first direction, the first beam is non-detachably connected to the housing, and the second beam is detachably connected to the housing. The battery pack according to the disclosure facilitates improving the safety performance and prolongs the service life.