Achieving Durable and Fast Charge Storage of MoO2-Based Insertion-Type Pseudocapacitive Electrodes via N-Doped Carbon Coating

MoO2, a particular transition metal oxide that possesses high intrinsic electronic conductivity and a one-dimensional tunnel structure, is becoming a prospective material for fast energy storage. Herein, N-doped carbon-coated MoO2(MoO2@NC) nanoribbons are synthesized via the polymerization of pyrrole and its following pyrolysis using MoO3 nanoribbons as a precursor. When assembled as electrodes for Li+ storage, benefiting from the well-designed structure, the optimized MoO2@NC-1-1 electrode with suitable carbon coating exhibits not only high capacity but also good rate and cycling performance. Initial capacities of 1475 C g(-1) (similar to 410 mAh g(-1)) at 1 mV s(-1) and 100 C g(-1) at an extremely high sweep rate of 2000 mV s(-1) are achieved. The capacity is obviously enhanced along cycling, and 180% of the initial value is remained after 20,000 cycles of cycling. Through in situ XRD measurement, it is found that there is no phase change but high reversible expansion/shrinkage of several certain crystal planes of the MoO2 during the insertion and removal of Li+, which should contribute to the high durability of the MoO2@NC-1-1 electrode.