Effective Cathode Design of Three-Layered Configuration for High-Energy Li-S Batteries.

ABSTRACT

A three-layered cathode structure was designed to minimize the shuttle effect of polysulfides and improve active material utilization. The three-layered configuration was fabricated by directly dropping pure sulfur composite slurry into multifunctional dual-barrier layers consisting of a self-standing TiO2/C interlayer and a very thin acetylene black layer (0.35 mg cm-2). In consequence, a decent discharge capacity of 963 mA h g-1 was acquired after 100 cycles at 0.1 C. With cycling at 0.1, 0.2, 0.5, 1, and 2 C, the cells displayed excellent reversible capacities of 1203, 1145, 1035, 934, and 820 mA h g-1, respectively. Furthermore, the cells still delivered a satisfactory discharge capacity of 799 mA h g-1 after 300 cycles at 0.5 C. The light mass of the three-layered configuration guarantees that the energy density is effectively improved, considering the overall mass of the cathode. The energy density (603 W h kg-1 after 100 cycles) was at a high level compared with those of the reported ones. Therefore, it is believed that the synergistic design for the three-layered cathode structure, which combines the mass-produced layer-by-layer structure, provides a novel protocol to the practical application of lithium-sulfur batteries.