Low-Pressure Argon/Hydrogen/Oxygen Plasma Treatment on LiMn2O4 Li-Ion Hybrid Supercapacitors

Abstract

LiCl + Mn(NO3)2·4H2O pastes are screen-printed on a carbon cloth substrate and then calcined at 400 °C for 6 h in a tube furnace to convert them into LiMn2O4. Ar, Ar+5%H2, or Ar+5%O2 low-pressure plasma is then used to treat the LiMn2O4/carbon cloth. The treated LiMn2O4/carbon cloth is then used as the electrode for a Li-ion hybrid supercapacitors (Li-HSCs) with a three-electrode configuration in 1-M Li2SO4 liquid electrolyte. Ag/AgCl and Pt electrodes were used as reference and counter electrodes, respectively. Li-HSCs are characterized by galvanostatic charging/discharging, cyclic voltammetry, and electrochemical impedance spectroscopy. The results indicate that plasma treatment improves the Li-HSCs performance. In particular, Ar+5%O2 plasma treatment increases the areal capacity by ∼24% to 23.12 μA h cm−2. It also improves the coulomb efficiency and capacity retention rate of LiMn2O4 Li-HSCs.