Coated TiCr Anode Active Material for Stable BCC Capacity
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Solution Overview
Problem
Existing TiCr-based hydrogen storing alloys with a body-centered cubic (BCC) structure as a metastable phase lack capacity properties, and it is difficult to produce them without vanadium, which is high-priced, while maintaining the BCC structure as a stable phase.
Innovation Solution
An anode active material is developed with a TiCr-based alloy containing a BCC metastable phase, coated with a layer of a catalyst metal and a metal with higher oxygen affinity than titanium, where an oxide film is present at the interface, and its oxygen dispersion is optimized through specific thickness and concentration conditions using Auger electron spectroscopy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the proportion of V is reduced in the hydrogen storing alloy, then the cost is reduced, but it becomes difficult to produce a hydrogen storing alloy including the BCC structure as a stable phase
Solution Approach 1:
The patent changes the production parameters by using gas atomizing method with specific cooling rates to produce a metastable BCC structure at room temperature. By controlling the atomization process parameters (gas pressure, atomization distance, cooling rate), the patent achieves a metastable BCC structure that would not form under equilibrium conditions, thereby resolving the contradiction between reducing V content and maintaining BCC structure stability.
Solution Approach 2:
The patent creates a composite structure with a metastable BCC phase as the matrix and intermetallic compounds (such as TiCr2, TiCr3, Ti5Cr3) as dispersed phases. This composite microstructure allows the material to maintain the desired BCC structure while using reduced V content, as the intermetallic compounds provide structural support and stability to the metastable matrix.
2Quantity of substance
If a TiCr-based hydrogen storing alloy with BCC metastable phase is produced without V, then the cost is reduced, but capacity properties do not appear and it does not work as an anode active material
Solution Approach 1:
The patent applies local quality by creating a non-uniform microstructure with specific intermetallic compounds dispersed throughout the metastable BCC matrix. The local composition and phase distribution are optimized to provide both structural stability and electrochemical activity, enabling capacity properties to appear in the V-reduced alloy while maintaining the metastable BCC structure.
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 anode active material exhibits excellent capacity properties by maintaining the BCC structure and dispersing oxygen effectively, enhancing the performance of alkaline storage batteries.
Implementation Method 1
an oxide film is present in an interface between the coating layer and the base material; and when a maximum oxygen concentration CMAX (at %) of the oxide film near the interface, and a position P1 where the CMAX is obtained, are determined by Auger electron spectroscopy
Implementation Method 2
when a maximum oxygen concentration CMAX (at %) of the oxide film near the interface, and a position P1 where the CMAX is obtained, are determined by Auger electron spectroscopy
Data Source
AI summary
A main object of the present disclosure is to provide an anode active material with excellent capacity properties. The present disclosure achieves the object by providing an anode active material to be used in an alkaline storage battery, the anode active material including: a base material containing Ti and Cr, and including a BCC structure as a metastable phase; and a coating layer that coats the base material, and contains a catalyst metal and a metal with oxygen affinity that is more than oxygen affinity of Ti; wherein an oxide film is present in an interface between the coating layer and the base material; and when a first thickness TA (nm) and a second thickness TB(nm) of the oxide film are determined by Auger electron spectroscopy, a rate of the TA with respect to the TB, which is TA/TB is, for example, 1.50 or more.