Coaxial α-MnSe@N-doped carbon double nanotubes as superior anode materials in Li/Na-ion half/full batteries

Coaxial nanotubes are a significant class of nanoscale building blocks for advanced electrodes of secondary batteries. Herein, one-dimensional (1D) coaxial double nanotubes (DNTs) consisting of alpha-MnSe inner tubes and N-doped carbon (N-C) outer tubes (abbreviated as alpha-MnSe@N-C DNTs) are successfully prepared and are demonstrated to be promising anode material for Li-ion and Na-ion batteries (LIBs/NIBs). When used in LIBs, it was revealed by ex situ XRD/HRTEM studies and electrode kinetics that a new electrochemical phase transition plays a crucial role in improving the cycling stability. As a result, the alpha-MnSe@N-C DNTs electrode delivers a high Li-storage capacity (800 mA h g(-1) at 50 mA g(-1)), excellent rate capability (405 mA h g(-1) at 14 A g(-1)) and ultra-long cycling stability (a high capacity retention of 87.2% even after 9000 cycles at 2 A g(-1)) with retained 1D morphology. In addition, the outer N-C nanotube can effectively protect the active alpha-MnSe inner nanotube to realize such outstanding electrochemical properties owing to the high electrical conductivity and particular 1D coaxial nanoarchitecture of the inner nanotube. Moreover, alpha-MnSe@N-C DNTs also exhibit excellent Li/Na-storage properties and full-cell performances when coupled with commercial LiFePO4 and LiNi0.6Co0.2Mn0.2O2 cathodes in LIBs as well as with the Na3V2(PO4)(2)O2F cathode in NIBs.