In‐Plane Assembled Single‐Crystalline T‐Nb2O5 Nanorods Derived from Few‐Layered Nb2CTx MXene Nanosheets for Advanced Li‐Ion Capacitors

Abstract Lithium‐ion capacitors (LICs) have attracted enormous interest thanks to their competitive power/energy densities and long‐duration lifespan. However, the sluggish insertion kinetics of battery‐type anodes seriously limits comprehensive performance of LICs. It is therefore imperative yet significant to develop advanced anodes with high‐rate Li + intercalation. Herein, first the in‐plane assembled single‐crystalline orthorhombic Nb 2 O 5 nanorods (T‐Nb 2 O 5 NRs) are designed and constructed via efficient hydrothermal and subsequent annealing treatment by employing few‐layered Nb 2 CT x nanosheets as a niobium‐based precursor. The inherent formation mechanism of single‐crystalline T‐Nb 2 O 5 NRs is tentatively proposed. When evaluated as anode material for LICs, the T‐Nb 2 O 5 NRs are endowed with robust crystalline skeletons and high diffusion dynamics benefiting from their appealing structure merits, and they exhibit a high‐rate capacity of ≈ 147 mAh g −1 at 2.0 A g −1 . The lithium storage process of the resultant single‐crystalline T‐Nb 2 O 5 is unveiled as well with in situ X‐ray diffraction analysis. Furthermore, the T‐Nb 2 O 5 NR‐based LICs display a large energy density of ≈ 35.6 Wh kg −1 at 8 kW kg −1 , along with exceptional capacity retention of ≈ 95% over 4000 cycles at 0.5 A g −1 . More significantly, the devised synthetic methodology and in‐depth insights here will stimulate extensive development of single‐crystalline T‐Nb 2 O 5 NRs for next‐generation LICs and beyond.