Secondary Battery Curved Electrode Gap Optimization

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Solution Overview

Problem

The energy density of secondary batteries with a large gap between the positive and negative electrodes decreases due to unused portions, leading to reduced performance.

Innovation Solution

The electrodes are designed with curved surfaces where the negative electrode protrudes from the positive electrode, creating a gap, and the ratio of the curvature radius difference between the electrodes to the gap is maintained between 0.50 to 1.10, optimizing the energy density and preventing short circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the gap between the positive electrode and the negative electrode is made large, then short circuit prevention is improved, but the energy density decreases due to increased unused portions

Engineering Contradiction:

Improveshort circuit preventionVSAvoidenergy density

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies curvature to the peripheral surfaces of both the positive and negative electrodes, creating curved surfaces that face each other across the gap. This curvature design allows the electrodes to maintain a larger gap distance for safety while reducing the area of unused portions at the edges, thereby improving energy density without compromising short circuit prevention

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent specifies precise parameter ranges: the gap G is controlled at 0.5mm to 2.0mm, and the curvature ratio |R1-R2|/G is maintained between 0.50 to 1.10. By optimizing these parameters, the design achieves both adequate gap distance for short circuit prevention and minimized unused areas for high energy density

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If the negative electrode protrudes from the positive electrode, then the curvature ratio can be optimized for energy density, but the structural complexity increases

Engineering Contradiction:

Improveenergy densityVSAvoidelectrode structure

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent introduces asymmetry by allowing the negative electrode to protrude from the positive electrode. This asymmetric configuration enables the negative electrode to have a larger curvature radius R1 compared to the positive electrode's curvature radius R2, optimizing the curvature ratio |R1-R2|/G for high energy density while maintaining manufacturability through straightforward electrode formation processes

Inventive Principle:

Principle #4Asymmetry

Data Source

PatentUS11342590B2Secondary battery

Publication Date: 2022.05.24 MURATA MFG CO LTD

AI summary

A secondary battery which includes an electrode assembly having a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, and an electrolyte, the electrode assembly and the electrolyte being accommodated in an exterior body. The positive electrode and the negative electrode have curved surfaces adjacent to each other on parts of peripheral surfaces in a planar view. The negative electrode is disposed so as to protrude from the positive electrode so that a gap G is present between the positive electrode and the negative electrode in the planar view. A value (|R1-R2|/G) obtained by dividing an absolute value |R1-R2| of a difference between a curvature radius R1 of the curved surface of the negative electrode and a curvature radius R2 of the curved surface of the positive electrode by the gap G is 0.50 to 1.10.