Hydrogen Storing Alloy Residual Magnetization Control
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Solution Overview
Problem
Hydrogen storing alloys used in nickel-hydrogen batteries for electric vehicles face issues with impurities leading to short circuits and reduced yield during magnetic separation treatment, which affects the battery's charge-discharge cycle ability and output characteristics.
Innovation Solution
A hydrogen storing alloy with a CaCu5 type crystal structure, comprising misch metal and elements like Ni, Al, Mn, and Co, is developed, with controlled residual magnetization and composition ratios to maintain high yield and reduce impurities, allowing for improved charge-discharge cycle ability and corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If magnetic separation treatment is applied to remove impurities, then purity is improved, but yield deteriorates due to loss of alloy material
Solution Approach 1:
The invention changes the magnetic properties parameter of the alloy by precisely controlling the residual magnetization to 0.03 emu/g or less through optimized composition ratios (ABx=4.95-5.05) and heat treatment parameters. This parameter change enables the alloy to be non-magnetic, allowing impurities to be removed by magnetic separation without the alloy itself being affected, thus resolving the contradiction between purity improvement and yield loss.
2Reliability
If Co content is increased to improve charge-discharge cycle ability, then reliability is improved, but cost and complexity increase
Solution Approach 1:
The invention optimizes the Co content parameter within a specific range (0.05-0.50 mol ratio) and controls the overall composition ratio ABx to 4.95-5.05, combined with heat treatment at 900-1100°C. This parameter optimization achieves the required charge-discharge cycle ability (retaining 80% or more of initial capacity after 500 cycles) while avoiding excessive Co addition, thus balancing reliability improvement with composition simplicity and cost control.
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 alloy achieves enhanced yield and charge-discharge cycle ability while minimizing impurities, leading to improved performance and longevity of nickel-hydrogen batteries, even without magnetic separation treatment.
Implementation Method 1
A hydrogen storing alloy is an alloy that reacts with hydrogen to form a metal hydride, and since the alloy can reversibly store and release a large amount of hydrogen in the vicinity of room temperature
Implementation Method 2
an alloy that reacts with hydrogen to form a metal hydride
Implementation Method 3
the alloy can reversibly store and release a large amount of hydrogen
Data Source
AI summary
A hydrogen storing alloy containing only a few impurities leading to a short circuit where the yield can be maintained even when the alloy is subjected to magnetic separation treatment. A hydrogen storing alloy includes a matrix phase having an AB5 type crystal structure, the alloy having a misch metal (referred to as “Mm”) in an A-site in an ABx composition and having any one or at least one of Ni, Al, Mn, and Co in a B-site in the ABx composition, wherein the ratio (referred to as “ABx”) of the total number of moles of elements comprising the B site to the total number of moles of elements comprising the A site is 5.00<ABx≦5.40; the content of Co is more than 0.0 mol % and less than 0.7 mol %; and residual magnetization is more than 0 emu/g and 0.020 emu/g or less.