Multi-Phase Hydrogen Storage Alloy Phase Composition
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Solution Overview
Problem
Existing metal hydride alloys for hydrogen storage and battery applications lack optimal electrochemical performance, particularly in high rate dischargeability and capacity retention.
Innovation Solution
Development of modified rare earth A2B7 type alloys with specific phase compositions, including hexagonal Ce2Ni7 and Pr5Co19 phases, and additional phases like MgZn2, CeNi3, and PuNi3, optimized through induction melting and annealing, enhancing electrochemical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional metal hydride alloys are used for hydrogen storage, then basic storage capacity is achieved, but electrochemical performance and high rate dischargeability are insufficient
Solution Approach 1:
The patent employs a multi-phase composite alloy system combining Ce2Ni7, Pr5Co19, and other phases. Each phase contributes different properties: Ce2Ni7 provides high hydrogen capacity, Pr5Co19 enhances electrochemical activity, and the combination achieves both high capacity and excellent high rate dischargeability that single-phase alloys cannot attain
Solution Approach 2:
The alloy design creates different phases with specialized functions distributed throughout the material. The Ce2Ni7 phase handles bulk hydrogen storage while Pr5Co19 phases provide surface reactivity and electrochemical activity, optimizing local properties for different functional requirements within the same material system
2Quantity of substance
If alloy composition is optimized for high capacity, then hydrogen storage capacity improves, but high rate dischargeability may be compromised
Solution Approach 1:
The multi-phase composite structure allows simultaneous optimization for both capacity and rate performance. Ce2Ni7 phase contributes high hydrogen capacity while Pr5Co19 phase provides fast electrochemical kinetics, achieving ≥96% HRD at 2nd cycle while maintaining high absolute capacity values
Solution Approach 2:
The patent systematically varies compositional parameters (rare earth content, transition metal ratios, phase abundances) to optimize the balance between capacity and discharge rate. Specific compositional ranges are identified that simultaneously maximize both hydrogen capacity and high rate dischargeability performance
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 alloys exhibit improved electrochemical performance with high discharge capacities and high rate dischargeability, along with better hydrogen diffusion and surface reactivity, making them suitable for advanced battery and fuel cell applications.
Implementation Method 1
Alloys capable of absorbing and desorbing hydrogen may be employed as hydrogen storage media
Implementation Method 2
The alloys contain a hexagonal Ce2Ni7 phase and a hexagonal Pr5Co19 phase, indicating phase transitions during hydrogen absorption and desorption
Implementation Method 3
Present alloys are prepared for instance via induction melting or arc melting under an inert atmosphere. The alloys may be further annealed under an inert atmosphere
Implementation Method 4
The alloys may be further annealed under an inert atmosphere, for instance at a temperature of
Data Source
AI summary
A multi-phase hydrogen storage alloy comprising a hexagonal Ce2Ni7 phase and a hexagonal Pr5Co19 phase, where the Ce2Ni7 phase abundance is > 30 wt% and the Pr5Co19 phase abundance is > 8 wt% and where the alloy comprises a mischmetal where Nd in the mischmetal is < 50 at% or a multi-phase hydrogen storage alloy comprising one or more rare earth elements, a hexagonal Ce2Ni7 phase and a hexagonal Pr5Co19 phase, where the Ce2Ni7 phase abundance is from about 30 to about 72 wt% and the Pr5Co19 phase abundance is > 8 wt% have improved electrochemical performance. The alloys are useful in an electrode in a metal hydride battery, a fuel cell or a metal hydride air battery.