A high-capacity and long-life negative electrode hydrogen storage material of LaMgNi type for secondary rechargeable nickel-metal hydride battery and a method for preparing the same are provided in the present invention. A chemical formula of the negative electrode hydrogen storage material of LaMgNi type is La.sub.1-x-yRe.sub.xMg.sub.y(Ni.sub.1-a-bAl.sub.aM.sub.b).sub.z, wherein Re is at least one of Ce, Pr, Nd, Sm, Y, and M is at least one of Ti, Cr, Mo, Nb, Ga, V, Si, Zn, Sn; 0x0.10, 0.3y0.5, 0<a0.05, 0b0.02, 2.3z<3.0. The negative electrode hydrogen storage material of LaMgNi type in the present invention has excellent charge-discharge capacity and cycle life. The negative electrode hydrogen storage material of LaMgNi type can be applied in both common secondary rechargeable nickel-metal hydride battery and secondary rechargeable nickel-metal hydride battery with ultra-low self-discharge and long-term storage performance.

An electrochemical direct heat to electricity converter includes a primary thermal energy source; a working fluid; an electrochemical cell comprising at least one membrane electrode assembly including a first porous electrode, a second porous electrode and at least one membrane, wherein the at least one membrane is sandwiched between the first and second porous electrodes and is a conductor of ions of the working fluid; an energy storage reservoir; and an external load. The electrochemical cell operates on heat to produce electricity. When thermal energy available from the primary thermal energy source is greater than necessary to meet demands of the external load, excess energy is stored in the energy storage reservoir, and when the thermal energy available from the primary thermal energy source is insufficient to meet the demands of the external load, at least a portion of the excess energy stored in the energy storage reservoir is used to supply power to the external load.

Disclosed herein is a regeneration method of a nickel-hydrogen battery provided with a positive electrode at least including nickel hydroxide. In the regeneration method, a regeneration process of charging a nickel-hydrogen battery is performed by supplying a square-wave pulse current set to a repetition frequency ranging from 5 kHz to 10 kHz and to an average value of current I.sub.AVE ranging from 1 A to 10 A.

A method of producing electrodes includes selecting a palladium alloy, annealing the palladium alloy at a first temperature above 350 C., cold working the palladium alloy into a desired electrode shape, and annealing the palladium alloy at a second temperatures and for a time sufficient to produce a grain size between about 5 microns and about 100 microns. The method further includes etching the palladium alloy, rinsing the palladium alloy with at least one of water and heavy water, and storing the palladium alloy in an inert environment.

The present disclosure relates to improved processes for the preparation of metal hydrides. The present disclosure also relates to metal hydrides, e.g., metal hydrides prepared by the processes described herein, that exhibit enhanced hydrogen storage capacity when used as hydrogen storage systems.

A negative electrode used in a nickel metal hydride secondary battery includes a negative electrode core body and a negative electrode mixture carried on the negative electrode core body. The negative electrode mixture includes hydrogen storage alloy powder which is an aggregate of hydrogen storage alloy particles, a binder, and a thickener. The hydrogen storage alloy particles have a volume mean particle size of 40 m or less and a concentration of chlorine of not less than 180 ppm to not more than 780 ppm.

An electrochemical direct heat to electricity converter includes a primary thermal energy source; a working fluid; an electrochemical cell comprising at least one membrane electrode assembly including a first porous electrode, a second porous electrode and at least one membrane, wherein the at least one membrane is sandwiched between the first and second porous electrodes and is a conductor of ions of the working fluid; an energy storage reservoir; and an external load. The electrochemical cell operates on heat to produce electricity. When thermal energy available from the primary thermal energy source is greater than necessary to meet demands of the external load, excess energy is stored in the energy storage reservoir, and when the thermal energy available from the primary thermal energy source is insufficient to meet the demands of the external load, at least a portion of the excess energy stored in the energy storage reservoir is used to supply power to the external load.

A nickel hydrogen secondary battery 2 has an electrode group 22 composed of a separator 28, a positive electrode 24 and a negative electrode 26, wherein the negative electrode 26 has a negative electrode core body and a negative electrode mixture held on the negative electrode core body; the negative electrode mixture comprises a hydrogen absorbing alloy powder composed of particles of a hydrogen absorbing alloy, a powder of an electroconductive agent, and a powder of a negative electrode additive; and the electroconductive agent is a hollow carbon black whose primary particle has a hollow-shell structure, and the negative electrode additive is a fluorine-containing anionic surfactant.

An electrochemical direct heat to electricity converter includes a primary thermal energy source; a working fluid; an electrochemical cell comprising at least one membrane electrode assembly including a first porous electrode, a second porous electrode and at least one membrane, wherein the at least one membrane is sandwiched between the first and second porous electrodes and is a conductor of ions of the working fluid; an energy storage reservoir; and an external load. The electrochemical cell operates on heat to produce electricity. When thermal energy available from the primary thermal energy source is greater than necessary to meet demands of the external load, excess energy is stored in the energy storage reservoir, and when the thermal energy available from the primary thermal energy source is insufficient to meet the demands of the external load, at least a portion of the excess energy stored in the energy storage reservoir is used to supply power to the external load.

An air electrode catalyst for an air secondary battery includes a pyrochlore-type composite oxide having two or more crystal structures having a different amount of oxygen. A battery, according to some embodiments, includes an electrode group including an air electrode and a negative electrode stacked with a separator therebetween, and a container accommodating the electrode group along with an alkali electrolyte solution, wherein the air electrode includes the air electrode catalyst. The air electrode catalyst may have a pyrochlore-type composite oxide having a crystal structure represented by Bi.sub.2Ru.sub.2O.sub.6.92 and a crystal structure represented by Bi.sub.2Ru.sub.2O.sub.7.33.