Nitrogen-doped carbon nanotube in-situ loaded LiNbO3 anode with high capacitance contribution for lithium-ion capacitors

LiNbO 3 is an intercalation material with high theoretical specific capacity, which is promising for lithium-ion capacitor (LIC) anode. However, the poor charge transfer dynamics makes LiNbO 3 unable to match the capacitive cathode in rate performance and cycle stability, resulting in poor electrochemical performance of the device. Herein, through the integrated process of in-situ nitrogen-doping with polypyrrole as the nitrogen source and hydrothermal deposition, the coaxial heterostructure of ultrafine LiNbO 3 nanoparticles and nitrogen-doped carbon nanotubes (NCNT) was realized. The large lithium-ion accessible surface and the bonding with the conductive channel significantly enhance the pseudocapacitive behavior of LiNbO 3 (capacitance contribution of 78.5% at 1 mV s −1 ). After 1000 cycles at a current density of 2 A g −1 , NCNT@LiNbO 3 still has a specific capacity of 154.9 mAh g −1 (89.8%). Thus, the assembled NCNT@LiNbO 3 //AC devices can charge and discharge up to 10000 cycles at a current density of 2 A g −1 , and the capacity retention rate can still reach 90.3%, and can provide an energy density of 142 Wh kg −1 . This work provides ideas for the interface and structure design of nanocomposite electrode materials.