Facile and Low-Cost Fabrication of Cathode Protection Thin Layer for Durable Li-S Batteries.

A new and cost-efficient way of confining the diffusing polysulfides within the sulfur cathode is presented on the basis of employing a porous diatomite that is highly abundant in nature. The sulfur cathode coated with diatomite layer exhibited a significantly reduced capacity fade during the first two cycles, implying that the loss of active materials due to the migration of polysulfides can be mitigated by the protective layer. The diatomite-layered cathode demonstrated excellent cycling stability as high as 85% after 100 cycles. These results clearly indicate that the polysulfide diffusion is effectively blocked and the dissolved polysulfides are well confined within the protected cathode region.

High-Energy-Density Li-S Batteries with Additional Elemental Sulfur Coated on a Thin-Film Separator.

For the development of high-areal-capacity Li-S batteries, sulfur-coated separators were utilized between the cathode and anode. It was found that (1) the additional sulfur on the separator participated at the electrode reaction occurring in the cathode region, contributing to the improvement of the areal capacity of Li-S batteries, and (2) the areal capacity significantly increased with the mass ratio of sulfur on the separator (Ssep) to sulfur in cathode (S+). At the high Ssep/S+ mass ratio of 5.0, the Li-S cell delivered fourfold higher areal capacity of 4.28 mAh/cm² than that of the control cell, along with excellent capacity retention of 90% after 50 cycles, demonstrating that the new concept for Li-S cells could be highly advantageous in boosting the Li-S battery cell performance. The new approach can be widely applied to increase the areal capacity and volumetric energy density of Li-S batteries.