Li2ZnTi3O8 as the host-separator modifier with efficient polysulfides trapping and fast Li+ diffusion for lithium-sulfur batteries

The diffusion and loss of lithium polysulfides (LiPSs) in lithium-sulfur batteries (LSBs) reduce the sulfur utilization rate and the catalytic conversion efficiency of sulfur species, resulting in early battery failure. Li2ZnTi3O8 (LZTO), characterized by its stable spinel structure, exhibits high Li+ conductivity and holds great potential as an effective adsorbent for LiPSs. This study proposes a collaborative design concept of LZTO host-separator modifier, which offers a complementary and matching approach in the cathode side, effectively addressing the challenges associated with dissolution and inadequate conversion of LiPSs. Density functional theory (DFT) calculation substantiates the pronounced chemical affinity of LZTO towards LiPSs. More importantly, the high efficiency ion transport channels are achieved in separator coating due to the presence of the LZTO particles. Furthermore, the catalytic efficacy of LZTO is validated through meticulous analysis of symmetric batteries and Tafel curves. Consequently, the LZTO host-separator modifier-based cell displays satisfactory rate capability (1449 and 1166 mAh·g−1 at 0.1 and 0.5 C) and an impressively capacity (606 mAh·g−1 after 500 cycles at 1 C). The coordinated strategy of host-separator modifier is supposed to have wide applications in LSBs.