A5B19 Hydrogen Storage Alloy Composition for High-Current Battery Performance
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Solution Overview
Problem
Alkaline storage batteries with A2B7 and A5B19 type hydrogen storage alloys face inadequate discharge characteristics and durability issues due to increased nickel proportion, leading to unstable metal hydrides and high hydrogen equilibrium pressure, which limits their performance in high-current applications like hybrid electric vehicles and pure electric vehicles.
Innovation Solution
A hydrogen storage alloy with a primary A5B19 structure, comprising a rare earth element like lanthanum and magnesium, and nickel, aluminum, and other elements, where the rare earth element is limited to maximally two elements, such as lanthanum and samarium, to control hydrogen absorption and desorption, and maintain a nickel molar ratio of 74% or more, achieving a hydrogen equilibrium pressure of 0.03-0.17 MPa, thereby enhancing output characteristics and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the nickel proportion is increased in A5B19 type hydrogen storage alloy to improve discharge characteristics, then active points for hydrogen adsorption and desorption are increased, but the gap between metal atoms becomes smaller causing unstable metal hydride formation and increased hydrogen equilibrium pressure
Solution Approach 1:
The invention changes the compositional parameters by precisely controlling the nickel content (70-80 atomic%) and adding specific elements (Co: 5-15 atomic%, Mn: 5-15 atomic%, Zn: 5-15 atomic%) to optimize the balance between discharge characteristics and hydrogen equilibrium pressure. This parameter optimization resolves the contradiction by finding the optimal composition range that provides sufficient active points while maintaining adequate atomic spacing.
Solution Approach 2:
The invention creates a composite alloy system combining multiple elements (rare earth, magnesium, nickel, aluminum, and transition metals) in specific proportions. This composite structure leverages the synergistic effects of different elements: nickel provides high conductivity and active points, cobalt enhances discharge characteristics, manganese improves cycle stability, and zinc helps control hydrogen equilibrium pressure, thereby resolving the contradiction between power output and reliability.
2Quantity of substance
If the gap between metal atoms is reduced by increasing nickel proportion, then more active points are available for hydrogen adsorption, but hydrogen atoms have difficulty entering the metal lattice leading to increased hydrogen equilibrium pressure
Solution Approach 1:
The invention applies local quality by creating a multi-element composite structure where different regions of the alloy have optimized local compositions. The presence of cobalt, manganese, and zinc creates local variations in atomic spacing and electronic structure, providing zones with optimal hydrogen absorption characteristics while maintaining overall high nickel content for sufficient active points, thus resolving the contradiction between quantity of active points and hydrogen equilibrium pressure.
Solution Approach 2:
The invention optimizes the compositional parameters within specific ranges (Ni: 70-80%, Co: 5-15%, Mn: 5-15%, Zn: 5-15%) to achieve the right balance. By controlling these parameters, the alloy maintains adequate atomic spacing for hydrogen entry while providing sufficient active points, resolving the contradiction between hydrogen adsorption capacity and hydrogen equilibrium pressure.
3Power
If particle size is reduced to improve output characteristics, then high current discharge performance is enhanced, but durability is reduced due to accelerated particle size reduction during charge/discharge cycles
Solution Approach 1:
The invention uses a composite alloy structure with multiple elements that work synergistically to enhance both output characteristics and durability. The specific combination of rare earth, magnesium, nickel, aluminum, cobalt, manganese, and zinc creates a stable composite material that maintains its structural integrity during charge/discharge cycles while providing excellent high-current performance, resolving the contradiction between power and durability.
Solution Approach 2:
The invention optimizes the compositional parameters within specific ranges to achieve a balance between output characteristics and durability. By controlling the content of each element (particularly the ratio of nickel to transition metals), the alloy achieves fine particle size for high output while maintaining resistance to particle size reduction during cycling, resolving the contradiction between power performance and durability.
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 structure provides output characteristics beyond conventional levels while maintaining durability and self-discharge performance, with a hydrogen storage alloy powder having a median particle size of 20 µm or less, suitable for high-output applications.
Implementation Method 1
enables improvement of hydrogen absorption and desorption cycle characteristics
Implementation Method 2
leading to formation of unstable metal hydride
Implementation Method 3
absorption hydrogen equilibrium pressure (Pa) is 0.03-0.17 MPa when the hydrogen amount absorbed in the hydrogen storage alloy (H/M (atomic ratio)) at 40°C is 0.5
Data Source
Figure 1
AI summary
A hydrogen storage alloy of the present invention includes component A including a rare earth element represented by Ln and magnesium and component B including elements containing at least nickel and aluminum, wherein a primary alloy phase of a hydrogen storage alloy represents an A5B19 type structure; a general formula is represented as Ln1-xMgxNiy-a-bAlaMb (wherein M represents at least one element selected from Co, Mn, and Zn; and 0.1 ≤ x ≤ 0.2, 3.6 ≤ y ≤ 3.9, 0.1 ≤ a ≤ 0.2, and 0 ≤ b ≤ 0.1); a rare earth element Ln includes maximally two elements containing at least La; and absorption hydrogen equilibrium pressure (Pa) is 0.03-0.17 MPa when the hydrogen amount absorbed in the hydrogen storage alloy (H/M (atomic ratio)) at 40°C is 0.5.