Complementary niobium-based heterostructure for ultrafast and durable lithium storage

Orthorhombic niobium pentoxide (T-Nb2O5) has been regarded as a potential anode candidate for high-power density lithium ion batteries (LIBs)/lithium ion capacitors (LICs). Unfortunately, the practical application of TNb2O5 anode is plagued by its poor intrinsic electronic conductivity and particle pulverization during the repeated lithiation/delithiation processes. Herein, VNbO4 @Nb2O5 heterostructure with complementary components was reported for the first time, in which the rutile VNbO4 with high electronic conductivity can accelerate electron transfer and stabilize the loose "room-pillar" structure of T-Nb2O5, while the T-Nb2O5 can contribute to optimize Li+ diffusion in VNbO4 and facilitate Li+ diffusion along the favorable path with low steric hindrance. Besides, the unique heterostructure can optimize the energy band structure and induce internal electric fields, thus further improving the ionic/electronic conductivity of VNbO4 @Nb2O5. As a result, VNbO4 @Nb2O5 demonstrates an exceptional rate capacity of 108.1 mAh g-1 even at 100 C and long cycle stability when evaluated as an anode for LIB. Moreover, the assembled quasi-solid state lithium ion capacitor constructed by VNbO4 @Nb2O5 anode and activated carbon (AC) cathode possesses a high energy density of 103.9 Wh kg-1 even at high power density of 12 kW kg-1