Pouch Battery Case Geometry to Eliminate Bat-Ear Dead Space
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Solution Overview
Problem
Pouch-type secondary batteries have unnecessarily protruding 'bat-ear' regions that increase dead space, degrade energy density, lead to inaccurate measurements, raise cracking risks, and increase cooling costs due to the height difference between peripheral and sealing portions during manufacturing.
Innovation Solution
A secondary battery case design with recessed cups and peripheral portions, where the width of the cups is greater than the dimensions of their corresponding peripheral portions, forming a specific angle and curvature to reduce the bat-ear by ensuring the peripheral portions tightly fit, thereby eliminating dead space and enhancing energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the peripheral portion and sealing portion are formed with standard dimensions during manufacturing, then the battery can be assembled, but bat-ear protrusions occur that increase dead space and reduce energy density
Solution Approach 1:
The patent applies local quality by creating different dimensional relationships at different locations of the battery case. Specifically, the cup width is designed to be greater than the corresponding peripheral portion dimension, while the sealing portion width equals its corresponding peripheral portion dimension. This localized dimensional differentiation prevents bat-ear protrusions at the cup region while maintaining proper sealing at the sealing portion, thereby eliminating dead space and improving energy density.
2Volume of stationary object
If the peripheral portion dimensions are reduced to eliminate bat-ear, then dead space is reduced, but the assemblability and structural integrity may be compromised
Solution Approach 1:
The invention maintains assemblability by applying different dimensional relationships to different portions of the case. The cup-corresponding peripheral portion is designed with a smaller dimension than the cup width to prevent protrusion, while the sealing-portion-corresponding peripheral portion maintains equal dimensions to ensure proper sealing and assembly. This localized differentiation preserves structural integrity and ease of assembly while eliminating dead space.
3Shape
If the cup width is made greater than the peripheral portion dimension, then bat-ear is eliminated, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by establishing specific dimensional relationships between case components. The cup width is set to be greater than the cup-corresponding peripheral portion dimension, creating a controlled dimensional difference that prevents bat-ear protrusion. This parameter adjustment maintains the desired case shape while providing clear manufacturing specifications that balance precision requirements with manufacturability.
Data Source
AI summary
A secondary battery case accommodates an electrode assembly having a structure in which electrodes and separators are alternately arranged, and includes a first cup having a recessed shape, a second cup having a recessed shape and provided on one side of the first cup, a first peripheral portion surrounding a perimeter of the first cup when the secondary battery case is unfolded, and a second peripheral portion surrounding a perimeter of the second cup when the secondary battery case is unfolded. The first peripheral portion includes a first cup-corresponding peripheral portion that corresponds to a width of the first cup, and the second peripheral portion includes a second cup-corresponding peripheral portion that corresponds to the second cup. The width of the first cup is greater than a length of the first cup-corresponding peripheral portion thereby reducing if not eliminated a bat-ear otherwise formed during manufacture.