Rate behavior of MoO₂/graphene oxide lithium-ion battery anodes from electrochemical contributions

The rate behavior of lithium batteries is one of the key topics for their wide applications. A MoO₂/graphene oxide nanohoneycomb synthesized by a preform-decomposition process displays a cycle induced activation behavior at the current densities of 0.1, 0.2, 0.5, and 1.0 A g⁻¹. The reversible capacities can reach to 1128, 759, 723 and 673 mAh g⁻¹ after 100 cycles, respectively. While it shows an almost constant capacity around 196 mAh g⁻¹ at a high current density of 10.0 A g⁻¹. The analyses based on the discharge/charge voltage profiles, their corresponding differential curves, rate cycle performance, as well as the phase analysis after discharging show the contributions of the reversible insertion of Li into the MoO₂ to form Li_0.98MoO₂, the reversible conversion reaction from Li_0.98MoO₂ to Mo and Li₂O, as well as surface adsorption at the current densities of 0.1, 0.2, 0.5, 1.0 A g⁻¹. When cycled at a higher current density, a large over potential happens during insertion/desertion process with a significantly decay of conversion reaction. The conversion reaction almost can not work at 10.0 A g⁻¹.