Subsurface Alloy Anode for Hydrogen Bromine Flow Battery
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Solution Overview
Problem
H2/Br2 battery systems are susceptible to electrocatalytic surface poisoning due to halide species, which complicates the measurement of bromine species adsorption on platinum-like metals, limiting cell life and efficiency.
Innovation Solution
The anode electrode in the H2/Br2 reduction-oxidation flow battery system is formed with a subsurface alloy of Cu/Pt(111) and/or Au/Pt(111), which reduces bromine adsorption through lower binding energy and maintains facile hydrogen dissociation, thereby resisting poisoning and enhancing battery lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a platinum-based catalyst is used in the anode electrode, then hydrogen dissociation is facilitated, but bromine adsorption occurs causing electrode poisoning and reduced cell life
Solution Approach 1:
The patent applies local quality by creating a subsurface alloy structure where Cu or Au atoms are positioned specifically beneath the Pt surface layer. This localized modification changes the electronic structure and binding properties only at the catalyst surface, maintaining hydrogen dissociation activity while reducing bromine adsorption. The subsurface alloying creates a gradient structure with different properties at different depths, optimizing both catalytic activity and poisoning resistance.
Solution Approach 2:
The patent employs composite materials by combining Pt with Cu or Au to form a subsurface alloy composite. This composite structure leverages the complementary properties of the constituent metals: Pt provides excellent hydrogen dissociation catalysis, while Cu or Au in the subsurface position reduces bromine binding energy. The synergistic effect of this composite material resolves the contradiction between maintaining catalytic activity and resisting poisoning.
2Power
If the battery system operates with high power capabilities, then energy delivery is improved, but susceptibility to halide poisoning increases, limiting cell life
Solution Approach 1:
The patent applies parameter changes by modifying the binding energy parameter of the catalyst surface through subsurface alloying. By changing the composition and structure of the catalyst (adding Cu or Au subsurface atoms), the binding energy for bromine is reduced while maintaining hydrogen dissociation capability. This parameter modification allows the system to operate at high power levels without the detrimental effects of strong bromine adsorption, thereby extending cell life.
3Ease of manufacture
If conventional electrodes are used, then manufacturing is simpler, but measurement of bromine adsorption is complicated due to poisoning effects
Solution Approach 1:
The patent introduces an intermediary approach by using Cu or Au subsurface atoms as mediators between the Pt catalyst surface and bromine species. These intermediary atoms modify the interaction between bromine and the catalyst, reducing adsorption strength. This mediation effect not only protects the electrode but also creates a more measurable system where bromine adsorption can be studied without complete surface blocking, facilitating research and optimization.
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 use of subsurface alloys in the anode electrode reduces bromine adsorption, increasing the battery's lifespan and maintaining high intrinsic reversibility and power capabilities, making it more resistant to poisoning and improving overall performance.
Implementation Method 1
reduces bromine adsorption through lower binding energy
Implementation Method 2
maintains facile hydrogen dissociation
Implementation Method 3
maintains facile hydrogen dissociation
Implementation Method 4
an electrolyte containing one or more dissolved electroactive species flows through an electrochemical cell that converts chemical energy to electricity
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A hydrogen/bromine reduction-oxidation flow battery system includes a bromine electrode, a hydrogen electrode, a membrane, a first catalyst, and a second catalyst. The membrane is positioned between the bromine electrode and the hydrogen electrode. The first catalyst is associated with the bromine electrode. The second catalyst is associated with the hydrogen electrode and at least partially formed from a subsurface alloy configured (i) to promote facile dissociation of H2, and (ii) to prevent bromide from adsorbing onto the hydrogen electrode.