Oxygen vacancies have demonstrated to be one of the most effective ways to alter electrochemical performance of electrodes for lithium ion batteries, though there is little information how oxygen vacancies affect the electrochemical properties. Vanadium pentoxide (V2O5) cathode has been investigated to explore the relationship among oxygen vacancies, surface energy, and electrochemical properties. The hydrogen-treated V2O5 (H-V2O5) sample synthesized via thermal treatment under H2 atmosphere possesses a high surface energy (63 mJ m(-2)) as compared to that of pristine V2O5 (40 mJ m(-2)) and delivers a high reversible capacity of 273.4 mAh g(-1) at a current density of 50 mA g(-1), retaining 189.0 mAh g(-1) when the current density increases to 2 A g(-1). It also displays a capacity retention of 92% after 100 cycles at 150 mA g(-1). The presence of surface oxygen vacancies increases surface energy and possibly serves as a nucleation center to facilitate phase transition during lithium ion intercalation and deintercalation processes.
Keywords: electrochemistry; oxygen vacancies; surface energy; surface energy analyzer; vanadium pentoxide.