Ni-MH Negative Electrode Alloy Composition for Faster Initial Activation
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Solution Overview
Problem
The existing hydrogen-absorbing alloy used in nickel-metal hydride batteries, as disclosed in JP 10-36930A, faces issues with initial activation and requires multiple break-in charge/discharge cycles to achieve optimal discharge capacity.
Innovation Solution
A negative electrode active material comprising a hydrogen-absorbing alloy with Ti, Zr, Cr, Mn, and Ni, further containing a small amount of La and Ce, forms a third phase that reduces Ni content in the AB2 type alloy phase, enhancing initial activation and discharge capacity with fewer charge/discharge cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the existing hydrogen-absorbing alloy (JP 10-36930A) is used, then the discharge capacity can be increased, but the initial activation is poor and multiple break-in charge/discharge cycles are required
Solution Approach 1:
The patent changes the compositional parameters of the hydrogen-absorbing alloy by adding specific rare earth elements (La, Ce) at controlled concentrations (0.1-5.0 at%). This compositional modification alters the alloy's activation characteristics, enabling excellent initial activation without requiring multiple break-in cycles, thus resolving the contradiction between reliability and time loss.
Solution Approach 2:
The patent creates a composite alloy system by combining traditional hydrogen-absorbing elements (Ti, Zr, Cr, Mn, Ni) with rare earth elements (La, Ce). This composite material approach leverages the synergistic effects of different elements to achieve both rapid initial activation and high discharge capacity, eliminating the need for extended break-in periods.
2Loss of time
If the number of break-in charge/discharge cycles is reduced, then time is saved, but the discharge capacity may not be optimized
Solution Approach 1:
The patent performs preliminary action by incorporating rare earth elements (La, Ce) into the alloy composition before battery operation. This pre-modification of the alloy structure ensures that the material is pre-conditioned for optimal performance, achieving both rapid activation and full discharge capacity without requiring subsequent break-in cycles.
Solution Approach 2:
By modifying the compositional parameters to include rare earth elements at specific concentrations, the patent fundamentally changes the activation behavior of the alloy. This parameter change enables the material to achieve optimal discharge capacity immediately or after minimal cycles, thus saving time without sacrificing reliability.
3Reliability
If more elements are added to the hydrogen-absorbing alloy, then the performance is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by selectively adding only specific rare earth elements (La, Ce) at precisely controlled low concentrations (0.1-5.0 at%). This targeted approach enhances performance through localized compositional modification rather than uniform complexity, maintaining manufacturing feasibility while achieving superior activation and discharge characteristics.
Solution Approach 2:
The patent manages complexity by changing parameters in a controlled manner - adding only two specific rare earth elements within defined concentration ranges. This parameter optimization approach improves performance without excessive complexity, as the additions are limited to specific elements at controlled levels rather than unrestricted multi-element formulations.
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 material achieves improved initial activation and increased discharge capacity with reduced break-in charge/discharge cycles, thanks to the formation of a third phase that contributes to charge/discharge activity.
Implementation Method 1
A hydrogen-absorbing alloy is used as a negative electrode active material of a nickel-metal hydride battery
Data Source
AI summary
The present disclosure provides a negative electrode active material for a nickel-metal hydride battery containing a hydrogen-absorbing alloy that contains Ti, Zr, Cr, Mn, and Ni, and further contains one or more elements selected from the group consisting of La and Ce, wherein a total content proportion of the one or more elements selected from the group consisting of La and Ce based on the entire hydrogen-absorbing alloy is 8 at % or less, and a method for producing the same.