Ageing Study of 26650 Type Li-ion Batteries Module at the Charge-Discharge Rates of 1 C

A 26650-type lithium-ion batteries module was cycled at the charge-discharge rates of 1 C at room temperature (20 +/- 2 degrees C) until its state-of-health (SOH) declined to 60%. Its degradation was investigated by capacity fading characterization, electrochemical impedance spectroscopy (EIS). The results show the cycle number of the module is 1300 cycles when its SOH declines from 100% to 60%. The film resistance R-f, charge transfer resistance R-ct and Warburg impedance ZW of the battery increase gradually with cycling while the ohmic resistance R-s is almost unchanged. Of all the resistances among R-s, R-f, R-ct and Z(w), the contribution of R-s to the impedance of the module is primary.