Preparation and characterization of 18650 Li(Ni 1/3Co 1/3Mn 1/3)O 2/graphite high power batteries

Abstract

The commercial 18650 Li(Ni 1/3Co 1/3Mn 1/3)O 2/graphite high power batteries were prepared and their electrochemical performance at temperatures of 25 and 50 °C was extensively investigated. The results showed that the charge-transfer resistance ( R ct) and solid electrolyte interface resistance ( R sei) of the high power batteries at 25 °C decreased as states of charge (SOC) increased from 0 to 60%, whereas R ct and R sei increased as SOC increased from 60 to 100%. The discharge plateau voltage of batteries reduced greatly with the increase in discharge rate at both 25 and 50 °C. The high power batteries could be discharged at a very wide current range to deliver most of their capacity and also showed excellent power cycling performance with discharge rate of as high as 10 C at 25 °C. The elevated working temperature did not influence the battery discharge capacity and cycling performance at lower discharge rates ( e.g. 0.5, 1, and 5 C), while it resulted in lower discharge capacity at higher discharge rates ( e.g. 10 and 15 C) and bad cycling performance at discharge rate of 10 C. The batteries also exhibited excellent cycle performance at charge rate of as high as 8 C and discharge rate of 10 C.