A conventional bipolar battery is constituted of a combination of cells hermetically sealed for preventing a liquid junction and preventing corrosion of a peripheral device due to a liquid leakage. Therefore, electrolytic solution injecting processes are carried out as many as the number of cells, so that much times and costs have been required for manufacturing a large-scale battery. In addition, a wiring space has been required since the cells are connected to one another with wires. The use of a current collector formed of a one-end closed tubular conductor, the current collector having a bottom protruding outward to form a protrusion, eliminates the wiring space and achieves a reduction in ohmic loss due to the wires. In addition, an electrolytic solution in one cell is separated by a water-repellent sheet from an electrolytic solution in another cell, so that a liquid junction is prevented.

A nickel hydrogen secondary battery accommodates an electrode group including a positive electrode and a negative electrode which are stacked one on top of another through a separator, together with an alkaline electrolyte. The battery contains Li, with a total amount of Li in the battery 2 of 15 to 50 mg/Ah, as determined as the mass in terms of LiOH per Ah of the positive electrode capacity. The negative electrode includes particles of rare earth-MgNi-based hydrogen storage alloy which contains a rare earth element, Mg and Ni. The hydrogen storage alloy particles 44 includes, on the surface thereof, a rare earth hydroxide which is the hydroxide of a rare earth element and has a specific surface area of 0.1 to 0.5 m.sup.2/g.

A negative electrode active material includes a hydrogen storage alloy. The hydrogen storage alloy has an A.sub.2B.sub.7 crystal structure. The hydrogen storage alloy includes nickel. The saturation magnetization per unit mass is 1.9 emu.Math.g.sup.1 or more.

Described are solid-state energy storage devices and methods of making solid-state energy storage devices in which components of the batteries are truly solid-state and do not comprise a gel. Useful electrodes include metals and metal oxides, and useful electrolytes include amorphous ceramic thin film electrolytes that permit conduction or migration of ions across the electrolyte. Disclosed methods of making solid-state energy storage devices include multi-stage deposition processes, in which an electrode is deposited in a first stage and an electrolyte is deposited in a second stage.

A battery includes an electrode group including an air electrode and a negative electrode stacked with a separator therebetween, and a battery case accommodating the electrode group along with an alkali electrolyte solution, wherein the air electrode includes an air electrode mixture containing a pyrochlore-type composite oxide and a manganese oxide, and the pyrochlore-type composite oxide is a bismuth-ruthenium oxide.

In an aspect, an electrochemical cell comprises: a positive electrode; a negative electrode, said negative electrode having an alloy having a composition comprising V; and an electrolyte; wherein an additive is provided in said electrolyte to form primary vanadate ions upon dissociation of said additive in said electrolyte; and wherein the electrochemical cell is a metal hydride battery. In some embodiments of this aspect, the alloy is configured to sorb hydrogen during charging of said electrochemical cell and desorb hydrogen during discharging of said electrochemical cell. In some embodiments of this aspect, the electrolyte has a pH selected from the range of 13 to 15.

The invention relates to a rare earth based hydrogen storage alloy, represented by the general formula (I):
RE.sub.xY.sub.yNi.sub.z-a-b-cMn.sub.aAl.sub.bM.sub.cZr.sub.ATi.sub.B(I)
wherein RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd; M denotes one or more element(s) selected from Cu, Fe, Co, Sn, V, W. The alloy has favorable pressure-composition-temperature characteristic, high hydrogen storage capacity, high electrochemical capacity. The alloy doesn't contain magnesium element, and the preparation process of the alloy is easy and safe.

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.

An ambient heat engine that is thermally coupled to its environment is provided. The ambient heat engine includes two complementary electrochemical cells. One cell has a positive voltage temperature coefficient and the other cell has a negative voltage temperature coefficient. The ambient heat engine further includes a controller and an electrical energy storage device. When the ambient temperature increases or decreases, the temperature variation creates a voltage differential between the two cells, and the controller discharges the higher voltage cell and uses a portion of the discharged energy to charge the lower voltage cell. The difference in energy is extracted by the controller and supplied to the electrical energy storage device. The controller includes circuitry for coupling energy from the energy storage device to the cells in order to compensate for self-discharge of the cells which may occur due to electronic leakage and diffusion phenomenon over extended periods of time.

Hydrogen storage negative electrodes based on group IV elements, for example hydrogen storage negative electrodes based on silicon and/or carbon, are highly effective towards reversibly charging/discharging hydrogen in an hydride electrochemical cell.