Synthesis And Electrochemical Properties Of Metal Hydroxide-modified Sulfur/Carbon Cathode For Lithium Sulfur Batteries

Lithium/sulfur (Li-S) battery is regarded as one of the most promising rechargeable battery systems, due to low cost, environmental friendliness, high specific capacity (1675 mAh g-1) and large energy density (2600 Wh Kg-1). However, the insulating nature of sulfur/Li2S and the polysulfide shuttle effect will cause loss of active mass, resulting in poor cyclic life, which hinder the practical application of lithium sulfur battery. In this research work, metal hydroxide-modified sulfur/carbon composite with novel structure have been successfully synthesized to improve electrochemical performance of sulfur cathode for Li-S battery.Cobalt hydroxide-covered sulfur/conductive carbon black composite (Co(OH)2@S/CCB) was prepared via thermal and hydrothermal treatments. In this composite, the sublimed sulfur is anchored in the CCB, followed by a uniform coating of Co(OH)2 nanosheets. As cathode materials of lithium-sulfur batteries, the as-prepared Co(OH)2@S/CCB electrode exhibits remarkable electrochemical performances. The electrode exhibits an initial capacity of 993 mAh g-1 at 0.1 C, after 100 cycles, the capacity remains 779 mAh g-1; even after 200 cycles at 1 C, it remains high capacity retention of 71.2% and high coulombic efficiencies above 97%.Nickel hydroxide-modified sulfur/conductive carbon black composite (Ni(OH)2@S/CCB) was synthesized through thermal treatment and chemical precipitation method. In this composite, the sublimed sulfur is stored into the CCB, and followed by a surface modification of Ni(OH)2 nanoparticles. As a cathode for Li-S battery, the as-prepared Ni(OH)2@S/CCB electrode exhibits preferable cycle stability. The electrode exhibits an initial capacity of 897 mAh g-1 at 0.2 C, after 100 cycles, the capacity remains 718 mAh g-1; even after 200 cycles at 1 C, it remains high capacity retention of 70.0% and high coulombic efficiencies above 94%.