Hydrogen-Absorbing Alloy Microstructure for Higher Discharge Capacity
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Solution Overview
Problem
Existing hydrogen absorbing alloys used as negative electrode materials face challenges with insufficient discharge capacity due to the absence of rare earth elements and high costs associated with expensive elements like Co, necessitating a solution that improves discharge capacity at low resource risk and cost.
Innovation Solution
A production method involving rapid molten metal cooling of alloys containing Ti, Zr, Cr, and Ni, followed by heat treatment, refines the texture and reforms the grain boundary phase, resulting in a hydrogen absorbing alloy with improved discharge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rare earth elements and expensive elements like Co are used in hydrogen absorbing alloys, then discharge capacity is improved, but resource risk and cost increase
Solution Approach 1:
The invention changes the compositional parameters by eliminating rare earth elements and reducing expensive Co content, while adjusting the ratios of alternative elements (Ti: 10-30 atom%, Zr: 10-30 atom%, Ni: 20-40 atom%, Mn: 5-20 atom%, Cr: 5-20 atom%) to achieve optimal discharge capacity without relying on traditional expensive components
Solution Approach 2:
The invention creates a composite alloy system combining multiple transition metals (Ti, Zr, Ni, Mn, Cr) in specific proportions to form a new material composition that achieves the required discharge capacity through synergistic effects of different elements, replacing the traditional rare earth-based single system
2Reliability
If rare earth elements and expensive elements like Co are used in hydrogen absorbing alloys, then discharge capacity is improved, but cost increases
Solution Approach 1:
The invention changes the compositional parameters by eliminating rare earth elements and reducing expensive Co content, while adjusting the ratios of alternative elements (Ti: 10-30 atom%, Zr: 10-30 atom%, Ni: 20-40 atom%, Mn: 5-20 atom%, Cr: 5-20 atom%) to achieve optimal discharge capacity without relying on traditional expensive components
Solution Approach 2:
The invention replaces expensive, scarce materials (rare earth elements and high Co content) with more abundant, cheaper transition metals, using elements that are more readily available in the periodic table to reduce material cost while maintaining functional performance
3Reliability
If molten metal is rapidly cooled to refine texture and reform grain boundary phase, then discharge capacity is improved, but manufacturing complexity increases
Solution Approach 1:
The invention utilizes phase transition during rapid cooling of molten metal, where the alloy transforms from liquid to solid state with specific crystal structures (AB2 Laves phase and AB cubic phase), forming desired microstructure and grain boundary phases through controlled solidification to enhance discharge capacity
Solution Approach 2:
The invention changes the thermal parameter by controlling cooling rate (1×10²°C/second to 1×10⁴°C/second) and heat treatment conditions (temperature and time parameters) to achieve the desired microstructure and phase distribution, optimizing discharge capacity through precise parameter 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 method enhances discharge capacity by refining the texture and reforming the grain boundary phase, leading to a negative electrode active material with improved charge-discharge activity and reduced resource risk and cost.
Implementation Method 1
cooling molten metal of a hydrogen absorbing alloy containing Ti, Zr, Cr, Mn, and Ni, at a speed of 1×10²° C./second to 1×10⁴° C./second
Implementation Method 2
performing heat treatment of the thin piece at 500° C. to 900° C. for 1 hour to 10 hours in a vacuum or an inert gas atmosphere
Data Source
AI summary
A production method for a negative electrode active material in the present disclosure includes: obtaining a thin piece by cooling molten metal of a hydrogen absorbing alloy containing Ti, Zr, Cr, Mn, and Ni, at a speed of 1×102° C./second to 1×104° C./second, at least to lower than 500° C.; and performing heat treatment of the thin piece at 500° C. to 900° C. for 1 hour to 10 hours in a vacuum or an inert gas atmosphere. The negative electrode active material obtained by the production method includes hydrogen absorbing alloy including a plurality of main phases and a grain boundary phase that exists between mutually adjacent main phases of the main phases, each of the main phases include an AB2 alloy phase, the grain boundary phase includes an AB alloy phase, and the average distance between the mutually adjacent main phases is 1.0 μm or less.