Hydrogen-absorbing alloy electrode electrolyte retention
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Solution Overview
Problem
Nickel-metal hydride storage batteries face challenges in maintaining the alkaline electrolyte solution within the separator during repeated charge-discharge cycles, leading to degradation in cycle life due to insufficient hydrogen-absorbing capability and corrosion issues with high cobalt content.
Innovation Solution
A hydrogen-absorbing alloy electrode comprising a first alloy with a rare-earth element, magnesium, nickel, and aluminum, and a second alloy with higher cobalt content, added to the first alloy, forming a Ce2Ni7 crystal structure and deposited cobalt compounds on the separator to retain the electrolyte, enhancing hydrogen-absorbing capacity and cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a hydrogen-absorbing alloy with high hydrogen-absorbing capability is used, then the capacity of the alkaline storage battery is improved, but the alkaline electrolyte solution within the separator dries up during repeated charge-discharge cycles, degrading cycle life
Solution Approach 1:
The patent changes the chemical composition parameters of the hydrogen-absorbing alloy by adding specific amounts of aluminum (0.1-0.5 mass%) and magnesium (0.1-0.5 mass%) to the rare-earth-nickel-based alloy. This compositional modification alters the alloy's properties to simultaneously achieve high hydrogen-absorbing capability and maintain electrolyte retention during cycling, resolving the contradiction between capacity and cycle life.
Solution Approach 2:
The patent creates a composite alloy system by combining rare-earth elements (La, Ce, Pr, Nd), nickel, and additional elements (aluminum, magnesium, and optionally cobalt, manganese, zinc). This multi-element composite structure synergistically improves both hydrogen-absorbing capability and electrolyte retention, allowing the battery to achieve high capacity while maintaining long cycle life.
2Reliability
If cobalt is added to improve corrosion resistance, then the stability of the alloy is improved, but the hydrogen-absorbing capability may be reduced
Solution Approach 1:
The patent applies local quality by adding cobalt (0.1-1.0 mass%) specifically to enhance corrosion resistance in the alloy structure, while maintaining the overall hydrogen-absorbing capability through the dominant rare-earth-nickel matrix and the synergistic effects of aluminum and magnesium additions. This localized element distribution allows simultaneous achievement of both properties.
Solution Approach 2:
The patent optimizes the cobalt content parameter within a specific range (0.1-1.0 mass%) to balance corrosion resistance and hydrogen-absorbing capability. By precisely controlling this compositional parameter, the alloy achieves improved corrosion resistance without significantly compromising hydrogen storage performance.
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
The solution effectively prevents electrolyte drying and improves the cycle life of alkaline storage batteries by maintaining electrolyte retention and corrosion resistance, with optimal cobalt content and particle size distribution in the second alloy.
Implementation Method 1
a hydrogen-absorbing alloy containing at least a rare-earth element, magnesium, nickel, and aluminum
Implementation Method 2
the hydrogen-absorbing alloy having a Ce2Ni7 type or a CeNi3 type crystal structure
Implementation Method 3
deposited cobalt compounds on the separator to retain the electrolyte
Data Source
AI summary
A hydrogen-absorbing alloy for a negative electrode in an alkaline storage battery includes a first hydrogen-absorbing alloy and a second first hydrogen-absorbing alloy. The first hydrogen-absorbing alloy contains at least a rare-earth element, Mg, Ni, and Al, and has an intensity ratio IA/IB of 0.1 or greater in X-ray diffraction analysis using Cu—Kα radiation as an X-ray source, where IA is the strongest peak intensity that appears in the range of 2θ=31° to 33°, and IB is the strongest peak intensity that appears in the range of 2θ=40° to 44°. The second hydrogen-absorbing alloy has a Co content greater than that of the first hydrogen-absorbing alloy.