Ingenious separator architecture: Revealing the versatile 3D heterostructured MXene-hydrogen titanate electrocatalysts for advanced lithium-sulfur battery

초록

Lithium-sulfur batteries (LSBs) with high theoretical energy density and cost-effectiveness have great promise as alternative energy storage systems to traditional lithium-ion batteries. Nevertheless, their practical application is severely hindered due to a myriad of shortcomings such as "shuttling effect" of lithium polysulfides (LiPSs), sluggish conversion kinetics of sulfur (S) species, low electrical conductivity of S and discharged products, and intractable lithium dendrite growth. Herein, a novel 3D-heterostructured electrocatalyst consisting of the in-situ grown H2Ti3O7 (HTO) nano-whiskers on a Ti3C2Tx (MXene) substrate (M-HTO-0.5) is designed using a MXenederived hydrothermal process combined with following ion exchange between Na+ and H+, wherein the hydrothermal reaction time regulation (0.5 h) mainly induces the balanced co-existence of HTO and MXene in the microstructure of M-HTO-0.5. Benefiting from the synergistic effect between M-HTO-0.5 (strong LiPS chemisorption, outstanding catalytic activity with abundant active sites, and boosted Li+ ion migration) and carbon nanotubes (CNTs) (construction of ion/electron transport network), the ingenious design of multi-functional separators (M-HTO-0.5-C) effectively restricts LiPS shuttling and dendritic Li growth simultaneously. Consequently, LSBs with M-HTO-0.5-C separators achieve remarkable rate capability, and stable long-term cyclability even at 5.0 C. This study opens an innovative avenue for developing high-performance LSB configurations.

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