Nitrogenated Urchin-like Nb2O5 Microspheres with Extraordinary Pseudocapacitive Properties for Lithium-Ion Capacitors

摘要

Recently, lithium-ion capacitors (LICs) combining the complementary characteristics of both lithium-ion batteries (LIBs) and supercapacitors, have received exhaustive investigation to meet the increasing demands for clean energy. However, their commercial application has been limited by the mismatch of charge-storage capacity and electrode kinetics between the capacitor-type cathode and battery-type anode. Thus, developing a novel high-power insertion anode material is the key to realizing excellent energy and power densities for LICs. Here, 3D hierarchical Nb2O5 microspheres assembled by surface-nitrogenated nanowires have been synthesized through a unique anti-solvent precipitation-assisted solvothermal route accompanied by a nitrogenization treatment, which can be successfully used for advanced LICs configuration. Owing to the high aspect ratio of ultrathin nanowires, unique pore structures caused by nitridation, improved electronic conductivity, and favorable kinetic stemming from pseudocapacitive behavior, the resultant nitrogenated Nb2O5 microspheres can deliver a high capacity of 205.3mAhg(-1) with remarkable rate capability and long lifespan. When constructed into a new LIC device with peanut-shell derived carbon (PSC) cathode, an exceptionally high energy density of approximate to 83.5Whkg(-1) and a high power density of 10kWkg(-1) with prominent cycling stability are realized. Significantly, the simultaneous manipulation of superstructure design and surface nitrogenization in novel anode material provides new opportunities to boost the energy and power densities for hybrid-ion capacitors.