Panasonic Intellectual Property Management Co., Ltd.

Sanyo Electric Co., Ltd.

Tatsuya Ishibashi

Masato Fujikawa

Yasunari Sugita

Kazuki Endo

Yukio Nishikawa

Hiroshi Tenmyo

A battery management device includes an SOC estimation unit, a storage unit, and a lithium deposition determination unit. The lithium deposition determination unit compares a differential coefficient of a battery voltage with respect to an SOC estimated by the SOC estimation unit and a differential coefficient of a battery voltage with respect to a reference SOC read from the storage unit, and determines that, if a difference is observed between the differential coefficients, lithium is deposited in a lithium ion secondary battery.

Cell management device and power supply device

A battery-state estimation device obtains, at a first timing, a first resistance value corresponding to a first open circuit voltage of a lithium-ion secondary battery and a second resistance value corresponding to a second open circuit voltage, which is higher than the first open circuit voltage, of the lithium-ion secondary battery. Further, the battery-state estimation device obtains, at a second timing which is different from the first timing, a third resistance value corresponding to the first open circuit voltage and a fourth resistance value corresponding to the second open circuit voltage. The battery-state estimation device determines presence or absence of lithium deposition in the lithium-ion secondary battery, based on a magnitude relation between a first variation amount of the third resistance value with respect to the first resistance value and a second variation amount of the fourth resistance value with respect to the second resistance value.

Battery-state estimation device

A charging system includes battery pack and charger. During the charge of secondary battery, charge control unit controls charger so that the charger performs constant-current charge at a first charge current, and, when at least one of the following conditions is satisfied, switches the first charge current to a second charge current lower than the first charge current and continues the constant-current charge. The conditions include the condition that the SOC of secondary battery arrives at a threshold SOC value and the condition that the inter-terminal voltage of secondary battery arrives at a threshold inter-terminal voltage. In response to the degree of degradation of secondary battery, the charge control unit drops at least one of the threshold SOC value and the threshold inter-terminal voltage.

Secondary-battery charging system and method and battery pack

A nonaqueous electrolyte secondary battery includes: an electrode group including a positive electrode plate, a negative electrode plate, and a separator. The positive and negative electrode plates are wound with the separator interposed therebetween. The positive electrode plate includes a first current collector exposed portion where a portion of the positive electrode current collector corresponding to an outermost portion of the electrode group is exposed over a length of greater than or equal to one turn in a winding direction of the electrode group, and a second current collector exposed portion where a portion of the positive electrode current collector corresponding to a middle portion of the electrode group is exposed over a length of greater than or equal to one turn in the winding direction. A positive electrode lead is provided on the second current collector exposed portion so as to be connected to an external electrode.

Nonaqueous electrolyte secondary cell

A lithium ion secondary battery includes an electrode group formed by winding a positive electrode having a positive electrode current collector and a positive electrode active material layer, and a negative electrode having a negative electrode current collector and a negative electrode active material layer, with a separator interposed between the electrodes. A wound positive electrode current collector exposing section faces a wound negative electrode current collector exposing section with the separator interposed therebetween, thereby forming a heteropolar electrode current collector facing zone corresponding to at least one turn in the electrode group. A unipolar electrode current collector facing zone, in which adjacent portions of the wound current collector exposing section or the wound current collector exposing section face each other directly or with the separator interposed therebetween corresponds to at least one turn in the electrode group.

Growing community of inventors

Osaka, Japan

Tatsuya Ishibashi