Method and apparatus for assessing lifespan of secondary battery
A method for predicting a lifespan of a secondary battery within a short time in a more accurate and effective way is provided. The method for assessing a lifespan of a secondary battery includes primarily aging a prepared secondary battery for a predetermined time, initially charging the primarily aged secondary battery to a predetermined SOC and secondarily aging the initially charged secondary battery for a duration greater than the primary aging. Additionally, degassing removes gas in the secondarily aged secondary battery. Further, the method includes charging the secondary battery with a primary low-current at C-rate of 1/15 C or less, after the degassing step, discharging the secondary battery with a primary low-current at C-rate of 1/15 C or less, after the primary low-current charging step and determining a lifespan of the secondary battery by using a difference of voltages measured at different time points.
1. A method for assessing a lifespan of a secondary battery, comprising:
primarily aging a prepared secondary battery for a predetermined time;
initially charging the primarily aged secondary battery to a predetermined SOC;
secondarily aging the initially charged secondary battery for a greater time duration than the primary aging;
degassing by removing gas in the secondarily aged secondary battery;
charging the secondary battery with a primary low-current charge at C-rate of 1/15 C or less, after the degassing step;
discharging the secondary battery with a primary low-current discharge at C-rate of 1/15 C or less, after charging with the primary low-current; and
determining a lifespan of the secondary battery by using a difference of voltages measured from the secondary battery at a plurality of different time points that correspond to a same accumulated capacity.
2. The method for assessing a lifespan of a secondary battery according to claim 1 ,
wherein during charging with the primary low-current, the secondary battery is fully charged at C-rate of 1/15 C or less, and
wherein during discharging with the primary low-current, the secondary battery is fully discharged at C-rate of 1/15 C or less.
3. The method for assessing a lifespan of a secondary battery according to claim 1 , wherein during initial charging, the secondary battery is charged to a state of charge of 30% or less.
4. The method for assessing a lifespan of a secondary battery according to claim 1 , wherein after discharging with the primary low-current and before determining the lifespan, further comprising:
charging with a secondary low-current the primarily low-current-discharged secondary battery at C-rate of 1/15 C or less; and
discharging with a secondary low-current of the secondary battery at C-rate of 1/15 C or less after the charging with the secondary low-current.
5. The method for assessing a lifespan of a secondary battery according to claim 4 , wherein in determining the lifespan, a voltage measured during the primary low-current charging and a voltage measured during the secondary low-current charging are compared to determine a lifespan of the secondary battery.
6. The method for assessing a lifespan of a secondary battery according to claim 1 , wherein the primary aging is performed for 10 hours to 14 hours, and the secondary aging is performed for 24 hours to 72 hours.
7. The method for assessing a lifespan of a secondary battery according to claim 1 , wherein in determining the lifespan, the difference of voltages measured at the plurality of different time points is compared with a reference value to determine whether the secondary battery has an acceptable value.
8. An apparatus for assessing a lifespan of a secondary battery, comprising:
a primary aging component configured to age a prepared secondary battery for a predetermined time;
an initial charging component configured to charge the primarily aged secondary battery to a predetermined state of charge;
a secondary aging component configured to age the initially charged secondary battery for a greater duration than the aging time by the primary aging component;
a degassing component configured to remove gas in the secondary battery secondarily aged by the secondary aging component;
a primary low-current charging component configured to charge the secondary battery, from which gas is removed by the degassing component, at C-rate of 1/15 C or less;
a primary low-current discharging component configured to discharge the secondary battery primarily charged by the primary low-current charging component at C-rate 1/15 C or less; and
a life determining component configured to determine a lifespan of the secondary battery by using a difference of voltages measured from the secondary battery at different two time points that correspond to a same accumulated capacity.