Hitachi, Ltd.

Shin-Kobe Electric Machinery Co., Ltd.

Yoshiaki Kumashiro

Hideki Miyazaki

Hiroshi Kimura

Katsunori Nishimura

Kazushige Kohno

Eiji Seki

Akihiko Emori

Masao Shimizu

Toshiyuki Kobayashi

Satoru Funaki

Hiroshi Haruna

Yoshimi Yanai

Akihiro Takanuma

Provided is a technique of achieving a longer-life lithium ion secondary battery. The lithium ion secondary battery includes a cathode including a cathode active material containing Mn, an anode including an anode active material containing graphite and non-aqueous electrolytic solution including electrolyte, and LiBFand LiPFare allowed to coexist in the non-aqueous electrolytic solution. Especially preferably LiPFis contained more than LiBFin the electrolytic solution. Preferably the electrolytic solution further includes iodide salt. As a result, an oxide of phosphor and boron is deposited on the cathode, thus preventing elution of Mn included in the cathode. The amount of these electrolytes is preferably in the decreasing order of phosphor, boron and then iodine.

Lithium-ion rechargeable battery

In a charging/discharging unit provided with: a lithium secondary battery, a voltage detecting sensor for detecting a voltage and a current detecting sensor; the charging/discharging control unit is further provided with a controller, and a discharging element for performing a constant voltage discharging operation of 3 V. A voltage, V, of the battery when a discharging operation is terminated (t=0) is measured by the voltage detecting sensor. If V&#x2266;3.6 V, within a rest time during which the battery is not charged/discharged until a next charging operation, a voltage, V, of the battery when a time, t, has elapsed is measured by the voltage detecting sensor. If this voltage charge is in a range of V-V&#x2267;0.2 V, then the constant voltage discharging operation of 3 V is carried out for a time duration longer than or equal to 1 hour.

Charging/discharging control unit for lithium secondary battery

A nonaqueous lithium secondary battery includes a positive electrode and a negative electrode capable of intercalating and releasing lithium ions and a separator. The negative electrode includes a collector and a negative electrode mixture layer formed on the collector. The negative electrode mixture layer includes at least a negative electrode active material and a binder. Nonconductive particles are buried in a top layer of the negative electrode mixture layer. The nonconductive particles and the negative electrode active material exist as a mixture in the top layer with a depth ranging from 1 to 20 &#x3bc;m. A volume ratio of nonconductive particles having a diameter equal to or less than 20 &#x3bc;m to a total volume of all the nonconductive particles and the negative electrode active material existing in the top layer of the negative electrode mixture layer ranges from 20 to 80%.

Nonaqueous lithium secondary battery

To provide a lithium secondary battery which suppresses a decrease in the charge and discharge efficiency during a battery storage test and which is excellent in maintaining the battery capacity after the storage test. There are disclosed a nonaqueous lithium battery, comprising: a positive electrode active material comprising a lithium-containing oxide capable of inserting and detaching lithium ions; a negative electrode active material comprising a carbon material capable of inserting and detaching lithium ions; and an electrolytic solution containing a lithium ion, wherein the surface of the negative electrode active material after initializing charging is coated with a compound derived from vinylene carbonate, and wherein a weight power density of the lithium battery is no less than 100 Wh/kg, and a method of producing a nonaqueous lithium battery comprising a step of sealing a positive electrode active material, a negative electrode active material, and a nonaqueous electrolytic solution using a sealed container, wherein a predetermined amount of vinylene carbonate is added into the nonaqueous electrolytic solution, and the initializing charging is carried out to form a coating on the surface of the negative electrode active material, the coating being derived from the vinylene carbonate.

Lithium secondary battery and production method of the same

A battery system includes a battery assembly having a plurality of modules, which are controlled by a system control circuit, each module including a module control circuit and a module by-pass circuit which is controlled via the module control circuit so as to suppress the charging variation among the plurality of modules. Each control circuit and the system-controlling circuit are connected to each other via a bilateral transmission medium and each module by-pass circuit is controlled based on information bilaterally transmitted between each module control circuit and the system control circuit via the bilateral transmission medium.

Battery system and electric vehicle using the battery system

During the charging of a secondary battery, the charging current is maintained, but the value of the current is changed for a short time, and the internal resistance of the battery is calculated from the voltage and the current before and after the changing of the charging current. The charging voltage is determined by adding an extra voltage equivalent to the voltage drop caused by the internal resistance to a designated voltage. Thus, it takes only a short time for stabilizing the voltage when the current is changed, because the charging current is not switched off completely. Therefore, the charging time can be shortened.

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Kasama, Japan

Yoshiaki Kumashiro