Wound Secondary Battery Electrode Layout to Prevent Anode Peeling

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Solution Overview

Problem

Existing secondary batteries face challenges in achieving high operation reliability due to issues such as high internal resistance and stress on the negative electrode active material layer.

Innovation Solution

A secondary battery design featuring an electrode wound body with a stacked configuration of positive and negative electrodes separated by separators, where the negative electrode active material layer includes edge parts that are positioned to reduce stress and prevent peeling from the current collector.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the negative electrode active material layer is extended to the edge of the current collector to increase capacity, then the battery capacity is improved, but the negative electrode active material layer is prone to peeling from the current collector

Engineering Contradiction:

Improvebattery capacityVSAvoidoperation reliability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies different edge configuration strategies to different electrodes: the negative electrode active material layer extends to the edge of the current collector to maximize capacity, while the positive electrode active material layer is deliberately retracted from the edge. This local differentiation allows the negative electrode to achieve high capacity without the peeling issues that would occur if both electrodes extended to the edges.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent designs the positive electrode to be retracted from the edge beforehand, creating a buffer zone that prevents stress concentration at the negative electrode edges. This preemptive design prevents the peeling problem before it occurs, allowing the negative electrode to extend fully to the edge without compromising reliability.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Ease of manufacture

If the electrode structure is simplified to reduce manufacturing complexity, then the ease of manufacture is improved, but the internal resistance increases

Engineering Contradiction:

Improveease of manufactureVSAvoidinternal resistance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent employs an asymmetric electrode configuration where the negative and positive electrodes have different edge positions. The negative electrode extends to the edge while the positive electrode is retracted, creating an asymmetric structure that optimizes both electrical performance (reduced internal resistance through better electron pathway utilization) and manufacturing simplicity.

Inventive Principle:

Principle #4Asymmetry

3Reliability

If the negative electrode active material layer is positioned closer to the central axis to reduce stress, then the peeling risk is reduced, but the battery capacity decreases

Engineering Contradiction:

Improveoperation reliabilityVSAvoidbattery capacity

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

Instead of retracting the negative electrode from the edge to reduce stress (which would decrease capacity), the patent inverts the approach by extending the negative electrode to the edge while retracting the positive electrode. This inverted strategy achieves stress reduction and peeling prevention while maintaining maximum negative electrode capacity.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS20250038370A1Secondary battery and battery pack

Publication Date: 2025.01.30 MURATA MFG CO LTD

AI summary

A secondary battery having higher operation reliability is provided. The secondary battery includes an electrode wound body, a positive electrode current collector plate, and a negative electrode current collector plate. The electrode wound body includes a positive electrode and a negative electrode. In a state where the electrode wound body is unwound, a negative electrode active material layer includes a third negative electrode edge part that is positioned to be inwardly retracted relative to a first intersection point at which an extension line of a first negative electrode edge part and an extension line of a second negative electrode edge part meet, and that couples the first negative electrode edge part and the second negative electrode edge part to each other. A second intersection point at which the first negative electrode edge part and the third negative electrode edge part meet is positioned between the first intersection point and a third intersection point, the third intersection point being a point at which the first negative electrode edge part and an extension line of a second positive electrode edge part meet.