One-step hydrothermal synthesis of Ni-Co sulfide on Ni foam as a binder-free electrode for lithium-sulfur batteries

NiCo2S4, Co3S4/NiS2 and Ni-Co sulfide grown on Ni-foam were successfully synthesized with a simple one-step hydrothermal method via adjusting the mass fraction of cobalt and sulphur source, forming a free-standing advanced hybrid electrode for Li-S battery. Interestingly, compared with typical synthesis methods of Ni-Co sulfide, this new synthetic method supplies nickel source through Ni-foam rather than soluble inorganic salt and avoid destroying the original structure in the process of secondary hydrothermal reaction. With the integrity of the whole mechanical structure of the hosts, the hybrid electrode behave strong chemical bonding for polysulfides and superior electrocatalytic activity for accelerating the polysulfides redox reactions. The results revealed that foam-like structure of S/Ni-foam@Ni-Co sulfide (S/NF@NCS-30) electrode delivers the highest capacity of 1352.36 mAh g-1 at 1 C after 10 cycles and the initial capacity of S/NF@NCS-30 electrode is 1920.28 mAh g-1 at 0.1 C. The results offer a facile and promising engineering strategy to achieve high sulfur utilization.