Sanyo Electric Co., Ltd.

Yasushi Kuroda

Koji Nishio

Mamoru Kimoto

Nobuyuki Higashiyama

Shin Fujitani

Teruhiko Imoto

Yoshinori Matsuura

Kikuko Kato

Ikuo Yonezu

Toshihiko Saito

Mitsuzou Nogami

Tadashi Ise

Masao Inoue

Mitsuzo Nogami

Takeo Hamamatsu

Takahiro Yamashita

Akio Furukawa

Hiroshi Sato

Hiroshi Fukuda

Takashi Nagase

Hirofumi Sako

Satoru Kometani

Yoshikazu Izumi

Nobuyoshi Oi

The battery charging detects battery temperature and includes a temperature maintaining charging operation wherein average charging current is controlled to drive battery temperature to a holding temperature, and charging is performed while maintaining battery temperature at that holding temperature. In addition, a temperature increasing charging operation occurs prior to the temperature maintaining charging operation. The battery is charged with a current which raises battery temperature until the holding temperature is reached. When battery temperature rises to the holding temperature in the temperature increasing charging operation, charging can transition to the temperature maintaining charging operation.

Battery charging method

In the present invention, a hydrogen absorbing alloy containing at least nickel, cobalt and aluminum, in which the sum a of the respective abundance ratios of cobalt atoms and aluminum atoms in a portion to a depth of 30 &angst; from its surface and the sum b of the respective abundance ratios of cobalt atoms and aluminum atoms in a bulk region inside thereof satisfy conditions of a/b&gE;1.30, or a hydrogen absorbing alloy containing at least nickel, cobalt, aluminum and manganese, in which the sum A of the respective abundance ratios of cobalt atoms, aluminum atoms and manganese atoms in a portion to a depth of 30 &angst; from its surface and the sum B of the respective abundance ratios of cobalt atoms, aluminum atoms and manganese atoms in a bulk region inside thereof satisfy conditions A/B&gE;1.20 is used for a hydrogen absorbing alloy electrode in an alkali secondary battery.

Hydrogen absorbing alloy electrode, method of fabricating hydrogen absorbing alloy electrode, and alkali secondary battery

An object of the present invention is to provide an effective hydrogen-absorbing alloy activation process which can enhance the electrochemical activity of a hydrogen-absorbing alloy and to provide a hydrogen-absorbing alloy electrode which, when used in a battery, ensures an excellent initial inner pressure characteristic, low-temperature discharge characteristic, high-rate discharge characteristic and cycle characteristic. In accordance with the present invention, a hydrogen-absorbing alloy electrode production process is provided which comprises an alloy activation treatment step of immersing a hydrogen-absorbing alloy in a strong acid treatment solution containing metal ions and, in the course of the pH rise of the acid treatment solution, adding an alkali to the acid treatment solution to promote the pH rise of the acid treatment solution.

Hydrogen storing alloy electrode and process for producing hydrogen storage alloy electrode

A rectangular battery having an electrode group which is inserted in a battery case having an airtight structure. The electrode group is formed by alternately stacking positive electrodes and negative electrodes via separators. The battery case is rectangular had has a closed bottom and an open part that is airtightly sealed by a cover. The outermost electrodes, which are located on both faces of the electrode group, are coated with an active material on a surface of a core. Furthermore, the outermost electrodes have the same polarity and the cores thereof directly contact an inside surface of the outer battery case. In one embodiment, the capacity of the outermost electrodes is smaller than the capacity of the inwardly disposed electrodes of the same polarity.

Rectangular battery

In the present invention, a hydrogen absorbing alloy containing at least nickel, cobalt and aluminum, in which the sum a of the respective abundance ratios of cobalt atoms and aluminum atoms in a portion to a depth of 30 .ANG. from its surface and the sum b of the respective abundance ratios of cobalt atoms and aluminum atoms in a bulk region inside thereof satisfy conditions of a/b.gtoreq.1.30, or a hydrogen absorbing alloy containing at least nickel, cobalt, aluminum and manganese, in which the sum A of the respective abundance ratios of cobalt atoms, aluminum atoms and manganese atoms in a portion to a depth of 30 .ANG. from its surface and the sum B of the respective abundance ratios of cobalt atoms, aluminum atoms and manganese atoms in a bulk region inside thereof satisfy conditions A/B.gtoreq.1.20 is used for a hydrogen absorbing alloy electrode in an alkali secondary battery.

Method of fabricating hydrogen absorbing alloy electrode

A hydrogen-absorbing alloy electrode for metal hydride alkaline batteries uses as hydrogen-absorbing material a powder of a rare earth element-nickel hydrogen-absorbing alloy obtained by pulverizing thin strips of said alloy prepared by single roll process and having an average thickness of 0.08 to 0.35 mm and a minimum size of crystal grains present in the roll-surface size of at least 0.2 .mu.m and a maximum size of crystal grains in the open-surface side of not more than 20 .mu.m. A process for producing the above electrode is also provided. The electrode can provide, when used as negative electrode, metal hydride alkaline batteries which are excellent in both high-rate discharge characteristics at an initial period of charge-discharge cycles and charge-discharge cycle characteristics.

Hydrogen-absorbing alloy electrode for metal hydride alkaline batteries

A hydrogen-absorbing alloy electrode for metal hydride alkaline batteries is obtained by coating or filling a collector with a hydrogen-absorbing alloy powder consisting essentially of spherical particles and/or nearly spherical particles and then sintering the powder, the powder having an average particle diameter of 30 to 70 .mu.m and containing 5 to 30% by volume of particles having a diameter of at least 2 times the average diameter and 10 to 40% by volume of particles having a diameter of not more than 1/2 of the average diameter. This electrode can give metal hydride alkaline batteries having excellent high-rate discharge characteristics and a long life.

Hydrogen-absorbing alloy electrode for metal hydride alkaline battery

Growing community of inventors

Itano-gun, Japan

Yasushi Kuroda