Battery Electrode Notch Design for Short-Circuit Prevention
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Solution Overview
Problem
Lithium ion secondary batteries with wound electrode bodies face challenges in preventing short-circuits due to bending of electrode corners, which can damage separators and lead to electrical shorts between positive and negative electrodes.
Innovation Solution
Incorporating a notch at the corner of the electrode plate, particularly in the active material layer non-existing section, helps suppress bending and reduce the risk of short-circuits by providing a more flexible area that minimizes contact with equipment during production, while also ensuring battery capacity and safety through the use of a protective layer and specific notch shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a wound electrode body is used to increase battery capacity, then the battery can accommodate more active material, but the electrode corners bend readily causing separator damage and short-circuits
Solution Approach 1:
The electrode plate is segmented by providing notches at the corners, dividing the continuous electrode structure into sections. This segmentation prevents the corner from bending as a continuous piece, thereby reducing the risk of separator damage and short-circuits while maintaining the overall battery capacity through the wound electrode body configuration.
Solution Approach 2:
The notch is specifically provided at the corner portion of the electrode plate where bending is most likely to occur. This local modification addresses the specific problem area without affecting the rest of the electrode structure, allowing the majority of the electrode to maintain its integrity and capacity while the corner is protected from bending-induced failures.
2Reliability
If the electrode plate structure is modified to prevent bending, then short-circuit risk is reduced, but the electrode active material area may be decreased
Solution Approach 1:
The notch is confined to the corner region of the electrode plate, creating a localized structural modification only where bending is most problematic. The majority of the electrode plate, including the central active material regions, remains intact and functional, thus protecting the separator without significantly reducing the overall active material area available for electrochemical reactions.
Solution Approach 2:
The notch removes only the minimal necessary material at the corner to prevent bending, rather than reducing the entire electrode structure. This partial action is sufficient to achieve the protective function while minimizing the loss of active material area, maintaining a balance between reliability and capacity.
Data Source
AI summary
Provided is technology for reducing further the risk of short-circuits between positive and negative electrodes in a battery having a wound electrode body. In a preferred embodiment of a battery disclosed herein, a first electrode plate has a first long edge and a second long edge that extend in the longitudinal direction. The first electrode plate has a first electrode core and a first electrode active material layer. The first electrode core has a first electrode active material layer existing section and a first electrode active material layer non-existing section. A plurality of first electrode tabs is provided on the first long edge. A first notch is provided at a first corner, on the first long edge side, of a winding initiation end portion of the first electrode plate. At least part of the first notch is provided in the first electrode active material layer non-existing section.