Hydrogen Storage Alloy Powder with Mg-Ni Gradient for Battery Performance
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Solution Overview
Problem
Nickel-hydrogen rechargeable batteries employing hydrogen storage alloys have not simultaneously achieved excellent initial activity, discharge capacity, and cycle characteristics, which are typically in a trade-off relationship.
Innovation Solution
A hydrogen storage alloy powder with a specific composition, represented by R1-aMgaNibAlcMd, featuring a Mg-rich/Ni-poor region at the surface and a Mg/Ni-containing region inside, where the Mg molar ratio in the surface region is higher and lower than in the bulk, respectively, and the Ni molar ratio is lower in the surface region and higher in the bulk, optimized for improved hydrogen migration and strain relief.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a hydrogen storage alloy with high initial activity is used, then the initial charge/discharge performance is improved, but the cycle characteristics deteriorate
Solution Approach 1:
The patent applies local quality by creating a non-uniform composition distribution within the alloy particles. The surface region has a different Mg/Ni ratio compared to the central region, with the surface having lower Mg content and higher Ni content. This local compositional variation allows the surface to provide high initial activity while the interior maintains structural stability for good cycle characteristics.
Solution Approach 2:
The patent creates a composite structure within the alloy particles, where the surface region and central region have different compositions. This internal composite structure combines the benefits of high initial activity from the surface region with the stability and long cycle life from the Mg/Ni-containing central region.
2Quantity of substance
If a hydrogen storage alloy with high discharge capacity is used, then the energy storage capability is improved, but the initial activity deteriorates
Solution Approach 1:
The patent uses local quality by assigning different functional roles to different regions of the alloy particles. The surface region with lower Mg content provides high initial activity and fast charge/discharge kinetics, while the central region with higher Mg content provides high discharge capacity through abundant hydrogen storage sites.
3Power
If an alloy composition is optimized for one performance parameter, then that parameter is improved, but other performance parameters deteriorate
Solution Approach 1:
The patent applies segmentation by dividing the alloy particle into functionally distinct regions: a surface region optimized for initial activity and a central region optimized for discharge capacity. This spatial segmentation allows each region to be optimized for its specific function without compromising the other performance parameters.
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 composition enhances the initial activity, discharge capacity, and cycle characteristics of nickel-hydrogen rechargeable batteries by smoothing hydrogen migration and relieving strain during absorption/desorption, leading to concurrent improvements in battery performance.
Implementation Method 1
the alloy powder has at its outermost surface a Mg-rich/Ni-poor region having a composition with a Mg molar ratio higher than that in formula (1) and a Ni molar ratio lower than that in formula (1), and has inside a Mg/Ni-containing region having a composition with a Mg molar ratio lower than that of said Mg-rich/Ni-poor region and a Ni molar ratio higher than that of said Mg-rich/Ni-poor region
Implementation Method 2
smoothing hydrogen migration and relieving strain during absorption/desorption
Data Source
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AI summary
Provided are hydrogen storage alloy powder capable of providing a nickel-hydrogen rechargeable battery with simultaneous excellence in initial activity, discharge capacity, and cycle characteristics, which are otherwise in a trade-off relationship, an anode for a nickel-hydrogen rechargeable battery as well as a nickel-hydrogen rechargeable battery employing the same. The hydrogen storage alloy has a particular composition represented by formula (1), R1-aMgaNibAlcMd, and has at its outermost surface a Mg-rich/Ni-poor region having a composition with a Mg molar ratio higher than that in formula (1) and a Ni molar ratio lower than that in formula (1), and has inside a Mg/Ni-containing region having a composition with a Mg molar ratio lower than and a Ni molar ratio higher than those in the Mg-rich/Ni-poor region.