Copper Phosphide Nanostructures Covalently Modified Ti 3 C 2 T x for Fast Lithium-Ion Storage by Enhanced Kinetics and Pesudocapacitance.

2D layer Ti 3 C 2 T x material attracts enormous attention in lithium ion energy storage field owing to the unique surface chemistry properties, but the material still suffers from restacking issue and the restriction on capacity. Herein, copper phosphide (Cu 3 P) nanostructures@Ti 3 C 2 T x composites are prepared by the in situ generation of Cu-BDC precursor in the bulk material followed with phosphorization. The uniformly distributed copper phosphide nanostructures effectively expand the interlayer spacing promoting the structural stability, and achieves the effective connection with the bulk material accelerating the diffusion and migration of lithium ions. The electrochemical activity of Cu 3 P also provides more lithium ion active sites for lithium storage. The X-ray photoelectron spectroscopy (XPS) analysis verifies that Ti─O─P bond with strong covalency allows the upper shift of maximum valence band and Fermi level, stimulating the charge transportation between Cu 3 P and the bulk Ti 3 C 2 T x for better electrode kinetics. 3Cu 3 P@Ti 3 C 2 T x exhibits excellent rate performance of 165.4 mAh g -1 at 3000 mA g -1 and the assembled 3Cu 3 P@Ti 3 C 2 T x //AC Lithium-ion hybrid capacitorsLIC exhibits superior energy density of 93.0 Wh kg -1 at the power density of 2367.3 W kg -1 . The results suggest that the interfacial modification of Ti 3 C 2 T x with transition metal phosphides will be advantageous to its high energy density application in lithium-ion storage.