Battery Electrode Notch Geometry for Tab-Root Crack Suppression
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Solution Overview
Problem
The strong compression of active material layers in battery electrodes to enhance volumetric energy density can cause cracking in the root of the tab portion of the electrode current collector and its vicinity, due to differential stretching and the expansion/contraction of the active material layer during charging and discharging.
Innovation Solution
A battery electrode design featuring a cutout defined by a first curve formed of a first arc and a straight line, from the root of the tab portion to the based portion or adjacent part of the based portion, effectively curbs cracking by reducing stress differences and accommodating expansion/contraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the active material layer is compressed with a strong force to increase packing density, then the volumetric energy density of the battery is enhanced, but cracking occurs in the root of the tab portion of the electrode current collector and its vicinity
Solution Approach 1:
The electrode current collector is segmented into a based portion and a tab portion by providing cutouts at the root of the tab portion. This segmentation allows the based portion to be compressed for high packing density while the tab portion remains relatively uncompressed, preventing cracking by distributing the compression stress across different segments rather than concentrating it at the root where the tab connects to the based portion.
2Quantity of substance
If the active material layer is strongly compressed to enhance volumetric energy density, then the packing density increases, but the electrode current collector experiences differential stretching and cracking
Solution Approach 1:
Different regions of the electrode current collector are given different mechanical properties through selective compression. The based portion is strongly compressed to achieve high packing density of the active material layer, while the tab portion is kept relatively uncompressed to maintain flexibility and resist cracking. The cutouts create a transition zone that gradually reduces compression stress, preventing sudden stress concentration and cracking at the root of the tab portion.
Data Source
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AI summary
A battery electrode which is one example of an embodiment is provided with a core and an active material layer disposed on the surface of the core. The core has a based part where the core surface is covered by the active material layer and a tab part projecting from the based part. Notches are formed on the core from the base of the tab part to the base part, or at portions where the base part adjoins the tab part. The edge of each notch is formed from a first curve comprising a first arc and either a second curve comprising a second arc having a smaller curvature than the first arc or a straight line. This allows a battery electrode to be provided such that the occurrence of cracks at the base of the tab part of the core and in the vicinity thereof can be sufficiently suppressed.