Coupling Niobia Nanorods with a Multicomponent Carbon Network for High Power Lithium-Ion Batteries.

High power lithium-ion batteries require highly conductive electrodes. For an active electrode material that has limited electron conductivity, it is critical to build a carbon network that is not only highly conductive itself but also highly compatible with the electroactive material for efficient interfacial charge transfer. Herein, we design a multicomponent carbon network that is optimized for electrical coupling with the electroactive Nb2O5 nanorods for efficient electron injection. The self-support electrode is constructed by using 0D polypyrrole-derived (Ppy) carbon nanoparticles as glue to bind the Nb2O5 nanorods with 1D carbon nanotubes (CNTs) and 2D graphene nanosheets (GNSs). The 0D carbon nanoparticles also cross-link 1D CNTs with 2D GNSs, which can effectively prevent the GNSs from aggregation and form the 3D CNT/GNS network that provides continuous electronic and ionic pathways. This 3D Nb2O5@C self-support electrode exhibits a high discharge capacity of 246.3 mA h g-1 at 0.5 C and 100 mA h g-1 at 20 C and excellent Coulombic efficiency of 99.98% at 20 C. Even increasing the mass loading to 7.1 mg cm-2, the Nb2O5@C electrode can still reach a discharge capacity of 172.4 mA h g-1 at 0.5 C after 100 cycles. A high power density of 1043 W kg-1 can be achieved at an energy density of 104.3 W h kg-1 based on the electrode weight, which is among the highest values demonstrated so far for Nb2O5 electrodes. The results pave the way toward practical applications of Nb2O5 anodes in high-power lithium-ion batteries.