A novel calendula-like MnNb2O6 anchored on graphene sheet as high-performance intercalation pseudocapacitive anode for lithium-ion capacitors

To balance the electrochemical performance gap between the Li+ insertion/deintercalation anode and the anion adsorption/desorption cathode, in this paper, for the first time, we investigated MnNb2O6 as a new rate capability type anode material for lithium-ion capacitors (LICs). Novel calendula-like MnNb2O6 particles anchored on reduced graphene oxide (rGO) were prepared via a simple two-step hydrothermal route. The special three-dimensional structure and cross-linked conductive network constructed by graphene could shorten the lithium-ion diffusion path, efficiently facilitate electron transmission and adapt to volume strain without shedding during the long-term charge/discharge process. This resulted in excellent charge storage capacity and reasonably superior cycling stability. MnNb2O6@rGO//AC LICs assembled with MnNb2O6@rGO as the cathode and activated carbon (AC) as the anode exhibited excellent performance with maximum energy density of 118 W h kg−1 and power density of 8000 W kg−1 based on the total mass loading of the active material weight. The initial capacity retention was up to 88% after 10 000 charge/discharge cycles, which was higher than that of bimetallic oxide materials reported so far. Therefore, this study might provide a novel rate capability anode material for LICs with high performance.