Yttrium Fluoride Negative Electrode for Cold-Charge Ni-H Batteries
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Solution Overview
Problem
Nickel-hydrogen secondary batteries face challenges in balancing cycle life characteristics and low-temperature charging characteristics, particularly when rare-earth fluoride additives are used in high concentrations, leading to degraded discharge capacity in cold environments.
Innovation Solution
Incorporating a hydrogen absorbing alloy negative electrode with an additive of yttrium fluoride in specific mass ratios, specifically 0.1 to 0.2 parts by mass based on 100 parts by mass of hydrogen absorbing alloy powder, to enhance both cycle life and low-temperature charging characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If rare-earth fluoride is added at high concentration to suppress corrosion and improve cycle life, then cycle life characteristics are improved, but low-temperature charging characteristics are degraded
Solution Approach 1:
The patent applies parameter changes by precisely controlling the concentration of rare-earth fluoride additive within the range of 0.01-0.5 mass%, and optimizing the ratio of rare-earth fluoride to alkaline earth metal fluoride (1:9 to 4:6). This quantitative parameter optimization resolves the contradiction by finding the optimal concentration point that provides sufficient corrosion protection while avoiding the harmful effects of excessive additive concentration that would degrade low-temperature charging characteristics.
Solution Approach 2:
The patent uses composite materials by combining rare-earth fluoride with alkaline earth metal fluoride in specific ratios. This composite approach allows the rare-earth fluoride to provide corrosion resistance for improved cycle life, while the alkaline earth metal fluoride component helps maintain low-temperature charging characteristics. The synergistic effect of the composite additive system resolves the technical contradiction between these two performance aspects.
2Object-affected harmful factors
If rare-earth fluoride additive is used to suppress corrosion of hydrogen absorbing alloy, then corrosion resistance is improved, but discharge capacity at low temperature is deteriorated
Solution Approach 1:
The patent optimizes the concentration parameter of rare-earth fluoride within 0.01-0.5 mass% and the compositional ratio with alkaline earth metal fluoride to achieve the balance between corrosion resistance and discharge capacity. This precise parameter control ensures sufficient corrosion protection without excessive additive concentration that would harm low-temperature discharge capacity.
Solution Approach 2:
The patent applies local quality by having the rare-earth fluoride specifically targeted at corrosion-prone areas of the hydrogen absorbing alloy surface, while the alkaline earth metal fluoride provides bulk performance maintenance. This localized protective function allows corrosion resistance improvement without significantly impacting overall discharge capacity.
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 addition of yttrium fluoride improves low-temperature charging characteristics and prolongs cycle life by inhibiting corrosion of the hydrogen absorbing alloy, maintaining capacity and performance in cold conditions.
Implementation Method 1
corrosion of the hydrogen absorbing alloy containing hydrogen, which is a negative electrode active material, by high concentration alkali as an electrolyte solution can be suppressed
Implementation Method 2
hydrogen absorbing alloy containing hydrogen, which is a negative electrode active material
Data Source
AI summary
A hydrogen absorbing alloy negative electrode is provided. The hydrogen absorbing alloy negative electrode has a hydrogen absorbing alloy, and an additive including yttrium fluoride. A mass of the yttrium fluoride is 0.1 parts by mass or more and 0.2 parts by mass or less based on a hydrogen absorbing alloy powder of 100 parts by mass.