Wound Secondary Battery End-Face Grooves for High-Rate Discharge
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Solution Overview
Problem
Existing secondary battery designs face challenges in high-rate discharging due to high internal resistance, leading to reduced battery capacity and the risk of internal short circuits, particularly when variations in the active material mixture layer dimensions are not considered, and the negative electrode active material can peel off during assembly, causing short circuits.
Innovation Solution
A secondary battery design with a band-shaped positive and negative electrode configuration, including uncovered parts and an insulating resin part, where the positive electrode active material uncovered part is coupled to the current collector, and the negative electrode active material uncovered parts are strategically positioned to prevent peeling, with grooves formed on the end faces to ensure flat surfaces and improve contact, reducing internal resistance and preventing short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the active material mixture layer dimensions are not adjusted for variations, then the manufacturing process is simpler, but the positive electrode active material covered part cannot be reliably opposed to the negative electrode active material covered part, resulting in reduced battery capacity
Solution Approach 1:
The patent applies preliminary action by providing an insulating resin part at the end part of the negative electrode in advance, before assembly. This insulating resin part serves as a positioning feature that ensures the positive electrode active material covered part is reliably opposed to the negative electrode active material covered part, eliminating alignment issues without requiring complex manufacturing adjustments
Solution Approach 2:
The insulating resin part acts as an intermediary element between the negative electrode active material covered part and the positive electrode. It provides a reliable reference surface that facilitates precise alignment during assembly, ensuring that the active material layers are properly opposed without requiring complex manufacturing processes
2Reliability
If the negative electrode is cut at the beginning and end of the active material mixture layer region, then the electrode structure is simplified, but the negative electrode active material can peel and fall off during assembly, causing internal short circuits
Solution Approach 1:
The insulating resin part is provided in advance at the end part of the negative electrode, serving as a preliminary protective measure. This prevents the negative electrode active material from peeling and falling off during assembly, as the insulating resin part reinforces the end region and provides structural support
Solution Approach 2:
The insulating resin part serves as a beforehand cushioning measure against the harmful effect of active material peeling. By providing this insulating reinforcement at the vulnerable end part of the negative electrode, the patent prevents peeling and falling off of active material during assembly, thereby preventing internal short circuits
Data Source
AI summary
A battery for high-rate discharging is provided that achieves a further increased battery capacity and is free from an internal short circuit. A negative electrode includes, on a negative electrode foil having a band shape, a negative electrode active material covered part covered with a negative electrode active material layer, a first negative electrode active material uncovered part extending in a longitudinal direction of the negative electrode foil, a second negative electrode active material uncovered part provided at an end part in the longitudinal direction on a beginning side of winding, and an insulating resin part provided between the negative electrode active material covered part and the first negative electrode active material uncovered part. A positive electrode active material uncovered part is coupled to a positive electrode current collector at one of end parts of an electrode wound body. The first negative electrode active material uncovered part is coupled to a negative electrode current collector at another of the end parts of the electrode wound body. The electrode wound body has one or more flat surfaces, in which the positive electrode active material uncovered part, the first negative electrode active material uncovered part, or both are bent toward a central axis of a wound structure to form the one or more flat surfaces, and a groove provided in each of the one or more flat surfaces.