Enhanced Cycle Stability of Li1.2Ni0.13Mn0.54Co0.13O2 Cathode with Sodium Oxalyldifluoroborate Electrolyte Salt for Hybrid Li-Na Ion Battery

Sodium oxalyldifluoroborate (NaODFB) electrolyte is, for the first time, examined as the electrolyte for a hybrid Li-Na ion battery. The solvent is propylene carbonate (PC) in this report. Li1.2Ni0.13Mn0.54Co0.13O2 (LNMCO) cathode exhibits better electrochemical performances in the NaODFB/PC electrolyte than those in the NaClO4/PC. The discharge capacity of LNMCO cathode shows a slight decrease from 202 mAh g(-1) at the 10(th) cycle to 186 mAh g(-1) at the 50(th) cycle in the NaODFB/PC, which is much better than that in the NaClO4/PC with a dramatically decreases from 190 mAh g(-1) at the 27(th) cycle to 76 mAh g(-1) at the 50(th) cycle. Moreover, in the NaODFB/PC, the LNMCO cathode attains a high discharge capacity of 151 mAh g(-1) at the 200(th) cycle even at 0.5 C. The better reversible cycling performance of the LNMCO cathode in the NaODFB/PC is believed to be the formation of a more stable cathode solid electrode interphase based on scanning electron microscopy and X-ray photoelectron spectroscopy.