Matsushita Electric Industrial Co., Ltd.

Hirokazu Kimiya

Isao Matsumoto

Hiroyuki Sakamoto

Hidekatsu Izumi

Yoichi Izumi

Akihiro Maeda

Yoshio Moriwaki

Youichi Izumi

A nickel positive electrode including an active material mixture mainly composed of a nickel oxide and an electrically conductive support, a metal and/or an oxide thereof including elements effective for increasing oxygen overvoltage, preferably at least one element selected from Ca, Ti, Nb, Cr, Y and Yb is contained in a conducting agent such as metallic Co and/or Co oxide added to supplement the electrical conductivity of the active material. By virtue of this construction, the decrease of charging efficiency caused by increase of battery temperature and decrease of the oxygen overvoltage with charging of the battery can be inhibited and the charging efficiency can be improved in a wide temperature atmosphere. Thus, a nickel-metal hydride storage battery of high capacity can be provided.

Alkaline storage battery

A process for producing positive electrode active material includes feeding an aqueous nickel salt solution, aqueous solutions of different kinds of metals, aqueous solution containing ammonium ions and aqueous alkali solution each independently and simultaneously into a reaction vessel such that the amount of alkali metal is 1.9-2.3 moles relative to 1 mole of the total amount of nickel and different kinds of metals and the amount of ammonium ions is 2 moles or more relative to 1 mole of the total amount of nickel and different kinds of metals, the pH in the vessel is 11-13, the temperature in the vessel is 30-60&deg; C. and the average residence time is 20-50 hours. Further, in the process step of continuously growing the complex metal oxide particles from the salts of a plurality of metal elements through a plurality of successive reaction-deposition stages, the compositions and/or the kinds of the salts of metal element groups used for forming the oxide in the reaction-deposition stages adjacent to each other are made to be different from each other.

Manufacturing method of active materials for the positive electrode in alkaline storage batteries

Disclosed is a high capacity positive active material for an alkaline storage battery comprising a nickel based multi-metals oxide, wherein the charge characteristic at high temperature is improved. This oxide has a large number of micropores in at least a surface layer. An average composition of the surface layer is different from that of the interior in that at least one element selected from the group consisting of Ca, Ti, Zn, Sr, Ba, Y, Cd, Co, Cr, Bi and lanthanoids, in addition to Ni, is contained in the surface layer, or in that the at least one element is contained at a concentration higher than that of the interior.

Positive electrode active material for alkaline storage batteries

A high energy density alkaline storage battery which uses a positive electrode including mainly nickel oxide is provided by increasing the capacities of the positive electrode and negative electrode. For increasing the capacity density of the positive electrode, the active material is incorporated as a solid solution with at least one element selected from manganese, chromium, aluminum and calcium in the range of from not less than 3 mol % to not more than 15 mol % relative to the active material, and the surface and/or the neighborhood of the surface of the active material are coated with a cobalt oxyhydroxide having a high electric conductivity of a specific resistance of 15 &OHgr;&middot;cm or less and a low crystallinity.

A process for producing positive electrode active material includes feeding an aqueous nickel salt solution, aqueous solutions of different kinds of metals, aqueous solution containing ammonium ions and aqueous alkali solution each independently and simultaneously into a reaction vessel such that the amount of alkali metal is 1.9-2.3 moles relative to 1 mole of the total amount of nickel and different kinds of metals and the amount of ammonium ions is 2 moles or more relative to 1 mole of the total amount of nickel and different kinds of metals, the pH in the vessel is 11-13, the temperature in the vessel is 30-60.degree. C. and the average residence time is 20-50 hours. Further, in the process step of continuously growing the complex metal oxide particles from the salts of a plurality of metal elements through a plurality of successive reaction-deposition stages, the compositions and/or the kinds of the salts of metal element groups used for forming the oxide in the reaction-deposition stages adjacent to each other are made to be different from each other.

Manufacturing method of active materials for the positive electrode in

Active materials for positive electrodes in alkaline storage batteries excellent in capacity density, discharge voltage, and high rate discharge characteristics can be provided by coating the surface of the active material powder with an .alpha.-like Al-substituted Ni(OH).sub.2. Moreover, active materials excellent in capacity density, discharge voltage and high rate discharge characteristics, and besides in high-temperature charging efficiency and/or charge and discharge characteristics can be provided by dissolving in solid state and/or coprecipitated state at least one different metal element selected from Ca, Cr, Y, Ti and Co in the .alpha.-like Al-substituted Ni(OH).sub.2 layer. Furthermore, active materials excellent in capacity density, discharge voltage and high rate discharge characteristics, and besides in charge and discharge characteristics can be provided by coating with a Co oxide the surface of the active material powder coated with the .alpha.-like Al-substituted Ni(OH).sub.2.

Active materials for the positive electrode in alkaline storage batteries

The present invention provides alkaline storage batteries of which high-rate discharge characteristic at low-temperature, cycle life, and storage performance at high-temperature are improved in good balance and the cost performance is superior even when the content of cobalt is made extremely low by using in the negative electrode consisting of hydrogen absorbing alloy powders based on MmNi system alloys comprising MmNi.sub.5 system alloy which remains mostly crystalline in phase when absorbing hydrogen and Mm.sub.2 Ni.sub.7 system alloy which turns mostly amorphous in phase upon absorbing hydrogen.

Negative electrode for alkaline storage batteries

Disclosed is a sealed alkaline storage battery with an increased utilization of a positive electrode active material comprising a nickel oxide and with drastically enhanced capacity density. The positive electrode active material is a nickel based multi-metals oxide containing at least one element such as Mn which promotes the formation of .gamma. phase during charging. The ratio A.sub..gamma. /A.sub..beta. of the integrated intensity A.sub..gamma. of the diffraction peak at d=about 7 angstroms attributed to the .gamma. phase to the integrated intensity A.sub..gamma. of the diffraction peak at d=about 4.5 to 5.0 angstroms attributed to the .beta. phase of the oxide in the completely charged state is not smaller than 0.4. The electrolyte comprises an aqueous solution containing at least one of K.sup.+ and Na.sup.+ as a cationic component and the total concentration of the above-mentioned cationic component in the completely charged state is within a range between 4 and 12 mol/l.

Growing community of inventors

Kyoto, Japan

Hirokazu Kimiya