Power storage device and charging method thereof

摘要

An object is to inhibit a decrease in the capacity of a power storage device or to compensate the capacity, by adjusting or rectifying an imbalance between a positive electrode and a negative electrode, which is caused by decomposition of an electrolyte solution at the negative electrode. Provided is a charging method of a power storage device including a positive electrode using an active material that exhibits two-phase reaction, a negative electrode, and an electrolyte solution. The method includes the steps of, after constant current charging, performing constant voltage charging with a voltage that does not cause decomposition of the electrolyte solution until a charging current becomes lower than or equal to a lower current value limit; and after the constant voltage charging, performing additional charging with a voltage that causes decomposition of the electrolyte solution until a resistance of the power storage device reaches a predetermined resistance.

主权项

1. A power storage device comprising:
a power storage unit comprising a secondary battery;
a detecting circuit configured to detect a capacity of the secondary battery; a memory configured to store a value; and a circuit configured to switch from first charging to second charging after the first charging is performed, the circuit comprising a first circuit, a second circuit, and a third circuit, wherein the first circuit is configured to compare, after the first charging, the capacity with the value stored in the memory, wherein at least one of the first to third circuits comprises a transistor comprising an oxide semiconductor film in a channel formation region,
wherein the second circuit is configured to start the second charging, and wherein the third circuit is configured to terminate the second charging when a resistance of the secondary battery reaches a predetermined resistance.