Rational Design of N-Doped CuS@C Nanowires toward High-Performance Half/Full Sodium-Ion Batteries

Transition-metal sulfides (TMSs) are considered excellent anode materials for sodium-ion batteries by virtue of decent capabilities based on multielectron conversion reactions. Herein, N-doped carbon-coated CuS nanowires (CuS NWs@NC) were facilely fabricated via a refluxing method, following in situ dopamine polymerization and sulfidation process. Employed as anodes for SIBs, the CuS NWs@NC deliver a highly invertible capacity of 571.1 mA h g-1 after 100 cycles at 0.2 A g-1 and a competitive rate capability of 294.4 mA h g-1 even at 20 A g-1. Remarkably, they exhibit a competitive long-life cyclic stability (216.7 mA h g-1 at 20 A g-1, 81.7% capacity retention over 10,000 cycles). Furthermore, the galvanostatic intermittent titration technique test reveals that the unique nanoarchitecture boosts the Na+ diffusion ability, guaranteeing superb cyclability and exceptional rate performance. Finally, a NVP/C||CuS NW@NC full battery was facilely constructed, which demonstrates a steady capacity of 220 mA h g-1 at 0.2 A g-1 over 200 cycles. The superior sodium storage performance is likely due to the one-dimensional coaxial core-shell nanoarchitecture and synergistic effect of the inner CuS nanowires with the outer conductive nitrogen-doped carbon layer, which provide a highway for fast electron/ion transport, restrain stress and agglomeration of CuS during cycling, and offer a significant capacitive-controlled capacity contribution. This scalable design provides a new strategy for improving the sodium storage property of other TMSs.