Construction of 3D porous Cu1.81S/nitrogen-doped carbon frameworks for ultrafast and long-cycle life sodium-ion storage

Transition metal sulfides have great potential as anode materials for sodium-ion batteries (SIBs) due to their high theoretical specific capacities. However, the inferior intrinsic conductivity and large volume variation during sodiation-desodiation processes seriously affect its high-rate and long-cycle performance, unbeneficial for the application as fast-charging and long-cycling SIBs anode. Herein, the three-dimensional porous Cu1.81S/nitrogen-doped carbon frameworks (Cu1.81S/NC) are synthesized by the simple and facile sol-gel and annealing processes, which can accommodate the volumetric expansion of Cu1.81S nanoparticles and accelerate the transmission of ions and electrons during Na+ insertion/extraction processes, exhibiting the excellent rate capability (250.6 mAh g-1 at 20 A g-1) and outstanding cycling stability (70% capacity retention for 6000 cycles at 10 A g-1) for SIBs. Moreover, the Na-ion full cells coupled with Na3V2(PO4)3/C cathode also demonstrate the satisfactory reversible specific capacity of 330.5 mAh g-1 at 5 A g-1 and long-cycle performance with the 86.9% capacity retention at 2.0 A g-1 after 750 cycles. This work proposes a promising way for the conversion-based metal sulfides for the applications as fast-charging sodium-ion battery anode.