Stacked Battery Electrode Positioning via Separator Creases
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Solution Overview
Problem
In stacked lithium ion batteries, the positional relationship between positive and negative electrodes becomes distorted due to differences in electrode size, leading to decreased battery performance, especially under shocks and vibrations, and existing solutions either increase the number of components or compromise volume efficiency.
Innovation Solution
The use of a stacked battery design where tabular positive and negative electrodes are laminated with separators, featuring bumping sections created by creases or joining sections to limit electrode movement, ensuring accurate positioning and preventing displacement during shocks or vibrations without increasing component count or reducing volume efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two separators are disposed between the positive and negative electrodes to maintain positional relationship, then the electrodes are prevented from moving away from original positions, but the distance between the electrodes increases and electric resistance increases
Solution Approach 1:
The single separator is segmented by forming creases at specific positions, creating multiple functional zones within one separator. The first crease forms a bumping section that limits electrode movement, while the second crease provides a welding portion for bonding separators. This segmentation allows the separator to perform multiple functions without increasing the number of separate components.
Solution Approach 2:
The creases are formed extending in the width direction of the separator, creating a three-dimensional structure with bumps and valleys. This dimensional change allows the separator to provide mechanical limiting function through the bumping section while maintaining electrical contact through the welding portion, resolving the contradiction between positional stability and electrical resistance.
2Reliability
If a plurality of separators are bonded together to fix the group of electrodes, then the electrodes are kept from moving away from original positions, but the welding portion of separator needs to stick out significantly, resulting in space between battery element and casing material
Solution Approach 1:
The separator has different local properties created by the creases: the first crease creates a bumping section with limited protrusion for mechanical support, while the second crease creates a welding portion for bonding. This local differentiation allows the separator to provide fixation function without requiring significant protrusion, thereby improving volume efficiency.
Solution Approach 2:
The creases are formed with specific parameters (depth, position, orientation) to optimize the balance between mechanical support and volume efficiency. The first crease is positioned to provide adequate bumping section for electrode fixation, while the second crease is positioned to enable welding without excessive protrusion, thus resolving the contradiction between reliability and volume efficiency.
3Reliability
If the positive and negative electrodes are both covered with separators to make external shapes equal in size, then the positional relationship is maintained, but the distance between electrodes increases
Solution Approach 1:
Multiple separators are bonded together at the welding portion to form an integrated structure. This merging allows the separators to work together as a single unit, providing mechanical support to maintain positional relationship while the integrated structure reduces the overall distance between electrodes compared to having separate separators, thus reducing electric resistance.
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 design effectively maintains the positional accuracy of electrodes, preventing performance decline under external stress and optimizing volume efficiency by limiting electrode movement with integrated bumping sections on the separators.
Implementation Method 1
the film casing material is pushed by the battery element with a strong force of 0.1 MPa because of atmospheric pressure
Implementation Method 2
a bumping section is provided to limit movements of the positive and negative electrodes as a positive-electrode end surface and a negative-electrode end surface hit the bumping section
Implementation Method 3
all separators laminated on electrode surfaces are bonded together with the creases or joining sections
Data Source
Figure 1A~1C
Figure 2A~2B
Figure 3A~3C
AI summary
A stacked battery includes a square battery element in which a tabular positive electrode, a separator and a tabular negative electrode are laminated, wherein: one side of the battery element is a terminal connection section pulled-out surface, which is provided on both the positive and negative electrodes and where a plate-like positive-electrode terminal connection section and a plate-like negative-electrode terminal connection are both pulled out; projection surfaces, which are generated by vertically projecting the positive-electrode terminal connection section and the negative-electrode terminal connection section onto surfaces extending from the positive and negative electrodes, do not cross each other; a surface of the positive electrode and a surface of the negative electrode, which are facing each other, are different in area; each electrode is disposed so that an entire projection portion, which is generated by projecting the small-area electrode onto a surface of a large-area electrode that faces the small-area electrode, is positioned on the large-area electrode; on a separator, a bumping section is provided to limit movements of positive and negative electrodes as a positive-electrode end surface and a negative-electrode end surface hit the bumping section; and as for the bumping section, separators are joined by a crease or joining section of adjacent separators among separators disposed on electrode surfaces.