Charging device, charging method, secondary battery, battery pack, electric vehicle, power storage device, electronic device, and power storage system using SOC
A charging device is provided. The charging device switches to a (n+1)-th charging rate from a n-th charging rate when constant current charging is performed on a secondary battery at the n-th charging rate, at an SOC smaller than an SOC at which a voltage local minimum value appears when an experimental battery is charged at the n-th charging rate. The (n+1)-th charging rate is lower than the n-th charging rate, and n is a natural number.
1. A charging device, comprising:
a voltage detection unit for detecting a secondary battery voltage;
a current detection unit for detecting a secondary battery current;
a control unit receiving a detection signal of the voltage detection unit and the current detection unit to control charging voltage/charging current; and
a DC/DC converter that is controlled by the control unit to supply current to the secondary battery,
wherein the charging device switches to a (n+1)-th charging rate from a n-th charging rate when constant current charging is performed on a secondary battery at the n-th charging rate, at a state of charge (SOC) of the secondary battery, of 0.8 times or more and 0.9 times or less of an SOC at which a voltage local minimum value appears according to an environmental temperature at start of charging when an experimental battery having a same type of negative electrode and electrolytic solution as the secondary battery and metallic lithium is charged at the n-th charging rate,
wherein the (n+1)-th charging rate is lower than the n-th charging rate, and n is a natural number, and
wherein, when the SOC of the secondary battery is 80% or more of the SOC of the experimental battery at which the voltage local minimum value appears, the charging device charges at the n-th charging rate until full charging without switching from the n-th charging rate to the (n+1)-th charging rate.
2. A power storage device comprising:
the charging device according to claim 1 ; and
the secondary battery,
wherein the power storage device is configured to supply power to an electronic device connected to the secondary battery.
3. A power storage system comprising:
the charging device according to claim 1 ; and
the secondary battery,
wherein a power storage device is configured to receive power from the secondary battery.
4. The charging device according to claim 1 , wherein the voltage local minimum value is a value of a voltage when a slope of the voltage is zero.
5. A charging method, comprising:
detecting a secondary battery voltage via a voltage detection unit;
detecting a secondary battery current via a current detection unit;
receiving a detection signal of the voltage detection unit and the current detection unit to control charging voltage/charging current;
controlling a DC/DC converter to supply current to the secondary battery; and
switching a secondary battery to a (n+1)-th charging rate from a n-th charging rate when constant current charging is performed on the secondary battery at the n-th charging rate, at a state of charge (SOC) of the secondary battery, of 0.8 times or more and 0.9 times or less of an SOC at which a voltage local minimum value appears according to an environmental temperature at start of charging when an experimental battery having a same type of negative electrode and electrolytic solution as the secondary battery and metallic lithium is charged at the n-th charging rate,
wherein the (n+1)-th charging rate is lower than the n-th charging rate, and n is a natural number, and
wherein, when the SOC of the secondary battery is 80% or more of the SOC of the experimental battery at which the voltage local minimum value appears, the charging device charges at the n-th charging rate until full charging without switching from the n-th charging rate to the (n+1)-th charging rate.