Porous hollow spherical Mg0.6Ni0.4O/S composite as cathode material for Li–S batteries

Highlights: • A Porous hollow spherical Mg_0.6Ni_0.4O/S composite had been fabricated by solvothermal and liquid infiltration method. • The hollow nanostructure can promote the electron transfer, but also mitigate the expansion of sulfur. • Mg_0.6Ni_0.4O induced stronger chemical adsorption ability for polysulfides. • This composite exhibited high capacity and long cycling life. Porous hollow Mg_0.6Ni_0.4O has been fabricated by simple solvothermal method and removed the template by calcining. Afterward, taking advantage of liquid infiltration method, we have successfully synthesized hollow Mg_0.6Ni_0.4O/S as positive material for Li-S battery with a sulfur loading of 59.9 wt%. Porous hollow structure not only promoted the electron transfer, but also mitigated the expansion of element sulfur in the process of charging and discharging. Under a current density of 200 mA g⁻¹, the reversible capacity was up to 912 mAh g⁻¹ after 65 cycles with a high rate performance, coulombic efficiency and a capacity retention of 98%. Especially, at a higher current density of 4000 mA g⁻¹, the reversible capacity maintained at 174.5 mAh g⁻¹ after 500 cycles. The excellent electrochemical performance was owe to Mg_0.6Ni_0.4O alleviating polysulfide dissolution in electrolyte and had unique catalytic effect on the Li/S redox reactions.