NiMH Negative Electrode Composition for Cycle Life and Cold Discharge
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Solution Overview
Problem
Conventional nickel-metal hydride secondary batteries face challenges in achieving both improved cycle life and low-temperature discharge characteristics, as methods to enhance cycle life often deteriorate the alloy's reactivity, particularly at low temperatures.
Innovation Solution
The negative electrode incorporates hydrogen storage alloy particles with a specific particle size range (15 µm to 90 µm) and yttrium fluoride particles (1 µm to 7 µm) to enhance reactivity and suppress corrosion, ensuring optimal dispersion and distribution within the alloy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Co is added to hydrogen storage alloy or alkali treatment is applied to suppress pulverization and corrosion, then cycle life is improved, but reactivity is deteriorated and low-temperature discharge characteristic is worsened
Solution Approach 1:
The invention changes the chemical composition parameters of the hydrogen storage alloy by adding specific elements (Al: 1-15 wt%, Si: 1-15 wt%, Ti: 1-10 wt%, V: 1-10 wt%, Zr: 1-10 wt%, Nb: 1-10 wt%) to improve cycle life while maintaining reactivity. This compositional parameter adjustment allows the alloy to achieve both long cycle life and good low-temperature discharge characteristics without the need for Co addition or alkali treatment
Solution Approach 2:
The invention creates a composite hydrogen storage alloy system by combining multiple elements (rare earth elements, Al, Si, Ti, V, Zr, Nb) to achieve synergistic effects. This composite material approach suppresses pulverization and corrosion while maintaining reactivity, resolving the contradiction between cycle life improvement and low-temperature discharge performance
2Reliability
If methods are applied to suppress corrosion and extend battery life, then reliability is improved, but alloy reactivity is reduced
Solution Approach 1:
The invention adjusts the compositional parameters of the hydrogen storage alloy by incorporating specific elements in controlled amounts. These parameter changes create a protective effect against corrosion while preserving the alloy's reactivity, eliminating the need for trade-offs between battery life and power output
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 configuration enhances the reactivity of the hydrogen storage alloy during low-temperature discharge while reducing corrosion, thereby improving both cycle life and low-temperature discharge characteristics of the battery.
Implementation Method 1
yttrium fluoride particles (1 µm to 7 µm) to enhance reactivity and suppress corrosion
Implementation Method 2
negative electrode mixture layer containing particles of hydrogen storage alloy and particles of yttrium fluoride
Implementation Method 3
yttrium fluoride particles (1 µm to 7 µm) to enhance reactivity and suppress corrosion
Data Source
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AI summary
A negative electrode for an alkaline storage battery that achieves both an improvement in cycle life and an improvement in low temperature discharge characteristics, and an alkaline storage battery including the negative electrode are provided. The negative electrode (26) for an alkaline storage battery according to the present invention includes a negative electrode core body formed of metal, and a negative electrode mixture layer which contains at least a hydrogen storage alloy and yttrium fluoride, and is carried on the negative electrode core body, and particles of the yttrium fluoride are formed so that the average particle size thereof is equal to 1 µm or more and 7 µm or less.