LiNi0.8Co0.2O2/MWCNT composite electrodes for supercapacitors

LiNi0.8Co0.2O2 prepared by a rheologic pretreatment gel-like method was used as the electrode materials for supercapacitors, and its electrochemical performance was investigated by galvanostatic charge/discharge testing. The almost linear discharge curves of the symmetric capacitors indicate that LiNi0.8Co0.2O2 has a capacitive characteristic. Different multiwalled carbon nanotubes (MWCNTs) and acetylene carbon black (AB) were used as the conductive additives of the LiNi0.8Co0.2O2, respectively. Under various current densities, the symmetric capacitors based on LiNi0.8Co0.2O2/MWCNT composite electrodes have good capacitive and energy characteristics. In contrast with AB, MWCNTs are more beneficial to increase the utilization of active materials. It can not only improve the capacitance and energy characteristics, but also retard greatly the capacitance fading of the LiNi0.8Co0.2O2-based capacitor. Both pore distributions and BET surface area are important for the different electrochemical performance of the MWCNTs used as conductive additives. MWCNTs with high mesoporous content more than 3 nm can avail to improve the capacitance and energy characteristics of the LiNi0.8Co0.2O2-based capacitor at high current density.