Spiral NiMH Electrode Layout for Battery Pressure Suppression
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Solution Overview
Problem
Nickel metal hydride secondary batteries experience high internal pressure due to gas generation during charging, which is not effectively managed by existing thinning methods at the winding start portion of the negative electrode.
Innovation Solution
The electrode design includes a band-shaped core with a spiral winding configuration, where the first circumference portion has a higher amount of reactant to consume generated gas, reducing internal pressure by enhancing gas consumption reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the mixture layer at the winding start portion of the negative electrode is thinned, then cost is reduced, but battery internal pressure increases
Solution Approach 1:
The patent applies local quality by creating different mixture layer thicknesses at different radial positions of the negative electrode. Specifically, the first circumference portion (winding start portion) has a thinner mixture layer than the intermediate and outermost circumference portions. This localized thinning reduces the amount of hydrogen absorbing alloy used (lowering cost) while the thicker portions at other locations maintain sufficient gas consumption capacity to control internal pressure.
Solution Approach 2:
The patent segments the negative electrode into three distinct radial zones: a first circumference portion (winding start), an intermediate portion (second and following circumferences), and an outermost circumference portion. Each zone has different mixture layer thickness characteristics, allowing optimized performance for cost reduction and pressure control in different regions of the electrode.
2Quantity of substance
If the mixture layer at the winding start portion is thinned, then material usage is reduced, but gas generation management deteriorates
Solution Approach 1:
The patent implements local quality by varying the mixture layer thickness across different radial positions. The first circumference portion has reduced mixture layer thickness to decrease material usage, while the intermediate and outermost circumference portions maintain greater thickness to ensure adequate hydrogen absorbing alloy content for consuming oxygen gas generated during charging, thus managing gas generation effectively.
Solution Approach 2:
The negative electrode is segmented into three radial zones with different mixture layer thicknesses. This segmentation allows the first circumference portion to use less material while the intermediate and outermost portions retain sufficient material to handle gas generation, thereby resolving the contradiction between material reduction and gas management.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively suppresses the rise in battery internal pressure, improving safety and maintaining performance by optimizing the distribution and amount of hydrogen absorbing alloy in the electrode mixture layers.
Implementation Method 1
The electrode mixture layer includes a reactant that develops a reaction consuming the gas generated at the ending period
Implementation Method 2
an electrode for an alkaline secondary battery... an electrode mixture layer including a hydrogen absorbing alloy
Data Source
AI summary
An electrode has a band-shaped core and an electrode mixture layer carried by the core to form a spiral electrode assembly with a gas generating electrode and a separator for an alkaline secondary battery. The electrode in the spiral shape has a first circumference portion, an intermediate portion, and an outermost circumference portion. The first circumference portion is a starting portion for winding into the spiral shape. The intermediate portion is a second and following circumferences of the spiral shape. The outermost circumference portion has an inner surface only which faces the gas generating electrode. The electrode mixture layer includes a reactant that develops a reaction consuming gas generated from the gas generating electrode. An amount of the reactant in the first circumference portion is more than those in the intermediate portion and/or the outermost circumference portion.