Alleviating the self-discharge and enhancing the polysulphides conversion kinetics with LaCO3OH nanocrystals decorated hierarchical porous carbon

Lithium-sulfur (Li-S) batteries have been recognized as one of the most promising energy storage devices due to their ultrahigh energy density of 2600 Wh kg-1. However, their practical implementation is greatly impeded by the sluggish sulfur conversion kinetics, detrimental shuttle effect and severe self-discharge. In this work, LaCO3OH nanocrystals decorated nitrogen-doped carbon nanosheet arrays (MNCS-La) are fabricated via an etching-embedding method, which is further applied as an advanced sulfur reservoir for Li-S batteries. The hi-erarchical porous architecture of carbon nanosheet arrays provides a huge pore volume, which not only buffers the volume fluctuation of active materials during the discharge-charge process, but also facilitates the electrolyte infiltration and ion diffusion. More importantly, the monodispersed LaCO3OH nanocrystals inhibit the shuttle effect and self-discharge by forming a strong La-S bond with lithium polysulfides (LiPSs) and simultaneously enhance the electrochemical conversion kinetics. Attributed to these synergistic features, the sulfur electrodes based on MNCS-La achieve enhanced electrochemical performance, such as an initial discharge capacity of 1230 mAh/g at 0.2 C and a low capacity attenuation of 0.048% per cycle after 1000 cycles at 1 C. This work provides a feasible structural design of host for the applications of Li-S batteries and calls more attention to lanthanide metals-based composite materials.

Automated summary

This work presents the fabrication of LaCO3OH nanocrystals decorated nitrogen-doped carbon nanosheet arrays (MNCS-La) as an advanced sulfur reservoir for Li-S batteries. The hierarchical porous architecture of carbon nanosheet arrays and monodispersed LaCO3OH nanocrystals inhibit the shuttle effect and self-discharge, and enhance the electrochemical conversion kinetics. The sulfur electrodes based on MNCS-La exhibit enhanced electrochemical performance.