Bimetallic Copper Tin Sulfide Nanosheet Arrays Encapsulated in Nitrogen-Doped Carbon Shells for Boosted Sodium Storage Performance

SnS2 has been conceived as a promising candidate for sodium-ion batteries (SIBs); however, the inferior intrinsic electrical conductivity, huge volume variation, and continuous pulverization upon cycling still hamper its practical application. To tackle these issues, a honeycomb-like hybrid architecture is delicately designed and constructed by encapsulating Cu-doped SnS2 nanosheet arrays in N-doped carbon coating (denoted as Cu–SnS2@NC). Benefitting from the synergistic effects of N-doped carbon coating and moderate Cu doping, the hybrid nanoarrays can effectively facilitate the ion/electron transfer ability, mitigate the mechanical stress, and improve the structural stability in the repeated Na+ insertion/extraction process. The optimal Cu–SnS2@NC nanoarrays display a remarkably high specific capacity of 1041.8 mA h g–1 at 0.1 A g–1 and much improved rate performance and cycling durability. By coupling the pseudocapacitive behavior-dominated Cu–SnS2@NC anode with the Na3V2(PO4)3 cathode, the full battery provides a high energy density of 232.4 W h kg–1 at a power density of 239.6 W kg–1. This work shall bring more insight into the ingenious design and fabrication of bimetallic sulfide arrays as advanced anodes for SIBs.