Influence of electrolyte additives on a cobalt oxide-based anode's electrochemical performance and its action mechanism

Abstract

To further illustrate the influence of different additives on the electrochemical performance of CoO composite-based anodes in lithium-ion batteries, a CoO/carbon nanofiber composite-based electrode has been constructed and its electrochemical performances are investigated in detail in 1 M LiPF₆–EC/DMC (1 : 1, v/v) electrolyte with different additives, i.e., vinylene carbonate, ethylene sulfite, lithium bisoxalatoborate, Li₂CO₃ and K₂CO₃. The results show that additional electrolyte additives have a great effect on the initial efficiency and capacity retention of CoO-based anodes. For example, better cyclic performance is produced in the presence of vinylene carbonate. The addition of Li₂CO₃ can accelerate the conductivity of lithium-ions, and improve greatly the initial efficiency, charge/discharge capacity and cycling performance as well. On adding Li₂CO₃, the initial efficiency increases from 75.1% to 81% and its reversible capacity can remain at 850 mA h g⁻¹ stably even after 100 cycles. The action mechanism of the SEI film between Li₂CO₃ additive and CoO composite anodes has been confirmed too.