Reliable Interlayer Based on Hybrid Nanocomposites and Carbon Nanotubes for Lithium–Sulfur Batteries

The future energy needs have triggered research interest in finding novel energy storage systems with high energy density. Lithium–sulfur batteries are regarded as one of the most promising options for the next-generation energy storage applications because of their high theoretical energy and low cost. However, the electrochemical performances of lithium–sulfur batteries are seriously compromised by the polysulfide (LiPS) shuttling and the insulating nature of sulfur. To overcome these issues, novel CoNi1/3Fe2O4 (CNFO) nanoparticles uniformly covered on the carbon nanotubes are now reported as an efficient functional interlayer. Benefiting from the sufficient sulfiphilic sites of the CNFO for chemically bonding with LiPSs, as well as the conductive interconnected skeleton of carbon nanotubes, this composite material showed great enhancement on the rate capability and cycle stability of Li–S batteries. The Li–S battery using this interlayer exhibited a high initial capacity of 897 mA h g–1 and a low capacity decay of 0.063% per cycle within 250 cycles at 2 C. Meanwhile, an reversible specific capacity of 869 mA h g–1 (at 0.5 C) with high Coulombic efficiency could be obtained over 100 cycles at an elevated temperature (60 °C). We speculated that the chemical adsorption of CNFO for polysulfide-anchoring is extremely critical for the performances of Li–S batteries under high temperature.