The present invention relates to a hydrogen storage alloy, an electrode for a Ni-MH battery, a secondary battery, and a method for preparing the hydrogen storage alloy. The chemical composition of the hydrogen storage alloy is expressed by the general formula La.sub.(3.03.2)xCe.sub.xZr.sub.ySm.sub.(1-(4.114.2)x-y)Ni.sub.zCo.sub.uMn.sub.vAl.sub.w, where x, y, z, u, v, w are molar ratios, and 0.14x0.17, 0.02y0.03, 4.60z+u+v+w5.33, 0.10u0.20, 0.25v0.30, and 0.30w0.40. The atomic ratio of the metal lanthanum (La) to the metal cerium (Ce) is fixed at 3.0 to 3.2, which satisfies the requirements of the overcharge performance of the electrode material. A side elements are largely substituted by samarium (Sm) element, that is, the atomic ratio of Sm on the A side is 25.6% to 42%, so as to solve the problem of shortened cycle life caused by the small amount of cobalt (Co) atoms. The equilibrium pressure is adjusted by the change in the ratio of Sm to La and Ce to satisfy the requirements of the charge and discharge dynamic performance of the electrode material. The nucleation rate of the solidification process is improved by the addition of zirconium (Zr) to the A side at an atomic ratio of 2% to 3%. The Ni-MH battery negative-electrode material obtained from the hydrogen storage alloy has high overcharge resistance, and good high-rate discharge performance and cycle stability.

According to one embodiment, an electrode composite is provided. The electrode composite includes a negative electrode active material-containing layer and an insulating particle layer. The negative electrode active material-containing layer includes negative electrode active material secondary particles having an average secondary particle size of from 1 m to 30 m. The insulating particle layer is provided on the negative electrode active material-containing layer. The insulating particle layer includes a first surface and a second surface opposed to the first surface. The first surface is in contact with the negative electrode active material-containing layer. The second surface has a surface roughness of 0.1 m or less.

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.

Provided is an electrode alloy powder that is useful to obtain a nickel-metal hydride storage battery having a high battery capacity and a reduced self-discharge. The alloy powder is: a mixture including particles of a first hydrogen storage alloy having an AB.sub.5-type crystal structure, and particles of at least one second hydrogen storage alloy selected from the group consisting of a hydrogen storage alloy a having an AB.sub.2-type crystal structure and a hydrogen storage alloy b having an AB.sub.3-type crystal structure, wherein an amount of the first hydrogen storage alloy included in the mixture is greater than 50 mass %.

The present disclosure concerns a method of producing a nickel-containing hydrogen storage alloy for use in a nickel metal hydride battery, the method comprising the steps: i. Providing a mixed active material comprising used positive electrode active material and used negative electrode active material; ii. Reducing the mixed active material, thereby obtaining a reduced active material; iii. Adding one or more metals to the reduced active material; iv. Remelting the mixture obtained in step iii; thereby obtaining a nickel-containing hydrogen storage alloy. The present disclosure also concerns nickel-containing hydrogen storage alloys obtained by the disclosed method.

A nickel hydrogen secondary battery 2 has an electrode group 22 including a separator 28, a positive electrode 24, and a negative electrode 26. The negative electrode 26 has a negative electrode core, and a negative electrode mixture held on the negative electrode core. The negative electrode mixture contains a hydrogen absorbing alloy and a water repellent. The hydrogen absorbing alloy has a composition represented by the general formula: Ln.sub.1-xMg.sub.xNi.sub.y-a-bAl.sub.aM.sub.b, where Ln represents at least one element selected from rare earth elements, Ti and Zr; M represents at least one element selected from V, Nb, Ta, and the like, and the subscripts a, b, x and y satisfy relations represented by 0.05a0.30, 0b0.50, 0x<0.05 and 2.8y3.9, respectively. The hydrogen absorbing alloy has a structure of an A.sub.2B.sub.7 type. The water repellent comprises a perfluoroalkoxyalkane.

A composition of general formula (1): Na.sub.x[Mn.sub.aNi.sub.bCr.sub.c]O.sub.2+y (1), wherein: 0.6?x?0.8; ?0.1?y?0.1; 0.55?a?0.7; 0.25?b?0.3; c?0.05; and a+b+c?1.0, an intermediate product for preparing a composition of general formula (1) and a process of synthesis, wherein the mixed sodium-transition metal oxide of general formula (1) may generally show an essentially or solely P2 structure, and may be used as a positive electrode material for a sodium ion secondary battery.

Hydrogen storage alloys comprising a metal oxide containing 60 at % oxygen; and/or comprising a metal region adjacent to a boundary region, which boundary region comprises at least one channel; and/or comprising a metal region adjacent to a boundary region, where the boundary region has a length and an average width, where the average width is from about 12 nm to about 1100 nm; and/or comprising a metal oxide zone comprising a metal oxide, which oxide zone is aligned with at least one channel; and/or comprising a Ni/Cr metal oxide have improved electrochemical properties, for instance improved low temperature electrochemical performance.

Electrode protection in electrochemical cells, and more specifically, electrode protection in both aqueous and non-aqueous electrochemical cells, including rechargeable lithium batteries, are presented. Advantageously, electrochemical cells described herein are not only compatible with environments that are typically unsuitable for lithium, but the cells may be also capable of displaying long cycle life, high lithium cycling efficiency, and high energy density.

According to one embodiment, an electrode composite is provided. The electrode composite includes a negative electrode active material-containing layer and an insulating particle layer. The negative electrode active material-containing layer includes negative electrode active material secondary particles having an average secondary particle size of from 1 m to 30 m. The insulating particle layer is provided on the negative electrode active material-containing layer. The insulating particle layer includes a first surface and a second surface opposed to the first surface. The first surface is in contact with the negative electrode active material-containing layer. The second surface has a surface roughness of 0.1 m or less.