NbN quantum dots anchored hollow carbon nanorods as efficient polysulfide immobilizer and lithium stabilizer for Li-S full batteries

Abstract

The shuttle effect of lithium polysulfides (LiPSs) and uncontrollable lithium dendrite growth seriously hinder the practical application of lithium-sulfur (Li-S) batteries. To simultaneously address such issues, monodispersed NbN quantum dots anchored on nitrogen-doped hollow carbon nanorods (NbN@NHCR) are elaborately developed as efficient LiPSs immobilizer and Li stabilizer for high-performance Li-S full batteries. Density functional theory (DFT) calculations and experimental characterizations demonstrate that the sulfiphilic and lithiophilic NbN@NHCR hybrid can not only efficiently immobilize the soluble LiPSs and facilitate diffusion-conversion kinetics for alleviating the shuttling effect, but also homogenize the distribution of Li+ ions and regulate uniform Li deposition for suppressing Li-dendrite growth. As a result, the assembled Li-S full batteries (NbN@NHCR-S||NbN@NHCR-Li) deliver excellent long-term cycling stability with a low decay rate of 0.031% per cycle over 1000 cycles at high rate of 2 C. Even at a high S loading of 5.8 mg cm−2 and a low electrolyte/sulfur ratio of 5.2 µL mg−1, a large areal capacity of 6.2 mA h cm−2 can be achieved in Li-S pouch cell at 0.1 C. This study provides a new perspective via designing a dual-functional sulfiphilic and lithiophilic hybrid to address serious issues of the shuttle effect of S cathode and dendrite growth of Li anode.