A First‐Cycle Coulombic Efficiency Higher than 100 % Observed for a Li₂MO₃ (M=Mo or Ru) Electrode

Abstract

The lithiation/de-lithiation behavior of a ternary oxide (Li 2 MO 3 , where M = Mo or Ru) is examined. In the first lithiation, the metal oxide (MO 2 ) component in Li 2 MO 3 is lithiated by a conversion reaction to generate nano-sized metal (M) particles and two equivalents of Li 2 O. As a result, one idling Li 2 O equivalent is generated from Li 2 MO 3 . In the delithiation period, three equivalents of Li 2 O react with M to generate MO 3 . The first-cycle Coulombic efficiency is theoretically 150 % since the initial Li 2 MO 3 takes four Li + ions and four electrons per formula unit, whereas the M component is oxidized to MO 3 by releasing six Li + ions and six electrons. In practice, the first-cycle Coulombic efficiency is less than 150 % owing to an irreversible charge consumption for electrolyte decomposition. The as-generated MO 3 is lithiated/de-lithiated from the second cycle with excellent cycle performance and rate capability.

Effects of Ru doping on the structural stability and electrochemical properties of Li2MoO3 cathode materials for Li-ion batteries

“…Furthermore, it was observed that in the 1 st cycle, the charge curve was different from that in consequent cycles for all considered samples, which was reported to be due to the inconsistent lithium removal and intercalation abilities of Li 2 MoO 3 in the first cycle. 46 Fig. 5(e and f ) shows the cycling performances of different samples at different current densities.…”