Alloy powder for electrodes includes first hydrogen-absorbing alloy particles having a spherical core portion, and non-spherical second hydrogen-absorbing alloy particles. The average particle diameter of the first hydrogen-absorbing alloy is 50 m or less. The content of the first hydrogen-absorbing alloy is less than 30 vol %.

A secondary electrochemical cell includes a negative electrode including as an output conductor, a metallic or metal-coated open-pore form or a metallic or metal-coated nonwoven, as a carbon-based storage material that enables storage of electrical charge in the electrode through formation of an electrical double layer (Helmholtz double layer), activated carbon having a BET surface area of at least 800 m.sup.2/g, a non-carbon-based H2 storage material that can chemisorb hydrogen and/or store it as a metal hydride, a positive electrode including as an output conductor, a metallic or metal-coated open-pore form or a metallic or metal-coated nonwoven, and nickel hydroxide and/or nickel oxyhydroxide, a porous separator that separates the negative electrode and the positive electrode from one another, an aqueous alkaline electrolyte with which the electrodes and the separator are soaked, and a housing that encases the electrodes, the separator and the electrolyte.

A secondary electrochemical cell includes a negative electrode including an output conductor, activated carbon having a BET surface area of at least 800 m.sup.2/g as a carbon-based storage material that enables storage of electrical charge in the electrode through formation of an electrical double layer (Helmholtz double layer), a positive electrode including an output conductor, and nickel hydroxide and/or nickel oxyhydroxide, a porous separator that separates the negative electrode and the positive electrode from one another, an aqueous alkaline electrolyte with which the electrodes and the separator are soaked, and a housing that encases the electrodes, the separator and the electrolyte.

A carbothermic reduction method is provided for reducing a La-, Ce-, MM-, and/or Y-containing oxide in the presence of carbon and a source of a reactant element comprising Si, Ge, Sn, Pb, As, Sb, Bi, and/or P to form an intermediate alloy material including a majority of La, Ce, MM, and/or Y and a minor amount of the reactant element. The intermediate material is useful as a master alloy for in making negative electrode materials for a metal hydride battery, as hydrogen storage alloys, as master alloy additive for addition to a melt of commercial Mg and Al alloys, steels, cast irons, and superalloys; or in reducing Sm.sub.2O.sub.3 to Sm metal for use in SmCo permanent magnets.

A negative electrode for a rechargeable lithium battery and a rechargeable lithium battery including the same. The negative electrode includes: a current collector; a first negative active material layer disposed on one side of the current collector and including a first negative active material and a linear conductive material; and a second negative active material layer disposed on one side of the first negative active material layer and including a second negative active material.

A nickel hydrogen secondary battery includes an outer can and an electrode group accommodated in the outer can in a sealed state together with an alkaline electrolyte. The electrode group includes a positive electrode and a negative electrode having a separator sandwiched therebetween, the alkaline electrolyte includes NaOH as the main solute, and the negative electrode includes a hydrogen storage alloy having a composition represented by a general formula: Ln.sub.1-xMg.sub.xNi.sub.y-zM.sub.z, wherein Ln is at least one element selected from rare earth elements and Zr; M is Al; subscripts x, y and z satisfy the following relations, respectively: 0x0.05, 3.3y3.6, and 0z0.50; and the content of La among rare earth elements in Ln is 25% or less.

It is an object of the present invention to improve the cycle performance in a nickel-metal hydride battery using a rare earth-MgNi type alloy. The present invention provides a nickel-metal hydride battery having a negative electrode including an LaMgNi based hydrogen absorbing alloy, wherein the hydrogen absorbing alloy has a crystal phase having Gd.sub.2Co.sub.7 type crystal structure and contains calcium.

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 hydrogen storage alloy suitable for a negative electrode of an alkaline storage battery is provided. The hydrogen storage alloy provided is a hydrogen storage alloy used for an alkaline storage battery that has, as a main phase, one or two crystal structures selected from an A.sub.2B.sub.7-type structure and an AB.sub.3-type structure, and that is represented by a general formula: (La.sub.1abCe.sub.aSm.sub.b).sub.1cMg.sub.cNi.sub.dAl.sub.eCr.sub.f (where suffixes a, b, c, d, e, and f in this formula (1) meet the following conditions: 0<a0.15; 0b0.15; 0.17c0.32; 0.02e0.10; 0f0.05; and 2.95d+e+f3.50.

A protective structure for use with metallic lithium (or other alkali or alkali earth metals) and its method of manufacture are provided. The protective structure may include a substantially continuous and substantially nonporous buffer layer disposed on the metallic lithium layer which is conductive to lithium ions. A substantially continuous and substantially nonporous protective layer may be disposed on the buffer layer.