MXene derivative Ta4C3-Ta2O5 heterostructure as bi-functional barrier for Li-S batteries

The shuttle effect of polysulfides during the charging and discharging of lithium-sulfur (Li-S) batteries and the growth of Li dendrites are crucial obstacles to hinder the commercialization of Li-S batteries. Heterostructure engineering is an effective strategy to accelerate catalytic conversion and suppress the dissolution of polysulfides. Herein, we report a Ta4C3-Ta2O5 heterostructure composite as a bi-functional modified separator that not only achieves effective protection for lithium metal but also accelerates the polysulfides redox kinetics process. This heterostructure possesses efficient chemical anchoring and abun-dant active sites to immobilize polysulfides by synergistic effect, which endows a stable long cycling per-formance for Li-S batteries. This corresponds to an initial high capacity of 801.9 mAh g -1 at 1 C with a decay rate of 0.086% for 500 cycles. Due to its high Young's modulus (up to 384 GPa), Ta4C3 contributes to forming a protective layer on the Li metal surface to inhibit the growth of Li dendrites. Accordingly, the symmetrical cell has a stable overpotential for 700 cycles at 20 mA cm-2/20 mAh cm-2. So, this "one stone two birds" design affords a novel perspective for high-energy Li-S battery storage system design and Li metal protection.(c) 2023 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.