Improved electrochemical performance of Li-doped natural graphite anode for lithium secondary batteries

Abstract

Lithium-doped natural graphite is synthesized by a simple wet ball-milling method and use as an anode material in lithium secondary batteries. The modified natural graphite is examined with a view to improved cycleability and columbic efficiency on the first charge–discharge cycle (irreversible capacity loss). Lithium-doping results in marked improvements in electrochemical performance. These are investigated by means of X-ray powder diffraction, impedance measurement, high resolution transmission electron microscopy, field emission scanning electron microscopy, and measurement of electrochemical capacity. LiO x intercalated at the edge planes reduces the electrolyte breakdown by passivating the highly reactive sites along these planes. The Li-doped natural graphite exhibits ∼5% reduction in the first irreversible capacity while the reversible capacity remains unchanged in comparison with pristine graphite electrode. Also, it has an excellent capacity retention of ∼99% after 50 cycles.