Small particles of metals in solution often behave like electrodes although they are not connected to a battery which determines their potential. However, when a chemical reaction occurs in the solution of such particles intermediate free radicals may transfer electrons to them. The particles are thus charged chemically and are able to act as a metal electrode on cathodic potential. Electron transfer reactions become possible at these micro-electrodes which cannot be brought about by the radicals in the absence of the colloidal catalyst.

Mechanism of reactions on colloidal microelectrodes and size quantization effects

Hydrogen storage alloys are of particular interest as a novel group in functional materials owing to their potential and practical applications in Ni/MH rechargeable batteries. This review is devoted to the specific alloy families developed for high-energy and high-power Ni/MH batteries in the last decades, especially for EV, HEV and PHEV applications. The scope of the work encompasses principles of Ni/MH batteries, electrochemical hydrogen storage thermodynamics and kinetics, prerequisites for hydrogen storage electrode alloys and recent advances in hydrogen storage electrode alloys. Rare earth AB5-type alloys, Ti- and Zr-based AB2-type alloys, Mg-based amorphous/nanocrystalline alloys, rare earth-Mg–Ni-based alloys and Ti–V-based alloys are highlighted. Additionally, the challenges met in developing advanced hydrogen storage alloys for Ni/MH rechargeable batteries are pointed out and some research directions are suggested.

Advanced hydrogen storage alloys for Ni/MH rechargeable batteries

Progress of hydrogen storage alloys for Ni-MH rechargeable power batteries in electric vehicles: A review

In this review article, the fundamentals of electrochemical reactions involving metal hydrides are explained, followed by a report of recent progress in hydrogen storage alloys for electrochemical applications. The status of various alloy systems, including AB₅, AB₂, A₂B₇-type, Ti-Ni-based, Mg-Ni-based, BCC, and Zr-Ni-based metal hydride alloys, for their most important electrochemical application, the nickel metal hydride battery, is summarized. Other electrochemical applications, such as Ni-hydrogen, fuel cell, Li-ion battery, air-metal hydride, and hybrid battery systems, also have been mentioned.

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The Current Status of Hydrogen Storage Alloy Development for Electrochemical Applications

An electrode material for an anode of a rechargeable lithium battery, containing a particulate comprising an amorphous Sn.A.X alloy with a substantially non-stoichiometric ratio composition. For said formula Sn.A.X, A indicates at least one kind of an element selected from a group consisting of transition metal elements, X indicates at least one kind of an element selected from a group consisting of O, F, N, Mg, Ba, Sr, Ca, La, Ce, Si, Ge, C, P, B, Pb, Bi, Sb, Al, Ga, In, Tl, Zn, Be, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, As, Se, Te, Li and S, where the element X is not always necessary to be contained. The content of the constituent element Sn of the amorphous Sn.A.X alloy is Sn/(Sn+A+X)=20 to 80 atomic %. An electrode structural body for a rechargeable lithium battery, comprising said electrode material for an anode and a collector comprising a material incapable of being alloyed with lithium in electrochemical reaction, and a rechargeable lithium battery having an anode comprising said electrode structural body.

Electrode material for anode of rechargeable lithium battery, electrode structural body using said electrode material, rechargeable lithium battery using said electrode structural body, process for producing said electrode structural body, and process for producing said rechargeable lithium battery

An improved battery utilizing a hydrogen rechargeable anode of a disordered non-equilibrium multicomponent material including one or more elements forming a host matrix and at least one modifier element incorporated therein. The anode is capable of electrochemically absorbing hydrogen from an electrolyte during application of a charging current thereto. The hydrogen is stored in the anode bulk until discharge is initiated, whereupon an electrical current is produced when the hydrogen is released. The superior battery of the invention has attained high density energy storage, efficient reversibility, high electrical efficiency, bulk hydrogen storage without structural change or poisoning and hence long cycle life and deep discharge capability.

B. Reichman

Papers

Rechargeable battery and electrode used therein

Effects of Mo additive on the structure and electrochemical properties of low-temperature AB5 metal hydride alloys

Effects of aluminum substitution in C14-rich multi-component alloys for NiMH battery application

Effect of molybdenum content on structural, gaseous storage, and electrochemical properties of C14-predominant AB2 metal hydride alloys

High catalytic activity disordered VTiZrNiCrCoMnAlSn hydrogen storage alloys for nickel–metal hydride batteries