Incorporating TiO₂ nanoparticles into the multichannels of electrospun carbon fibers to increase the adsorption of polysulfides in room temperature sodium-sulfur batteries

With the rapid development of electric vehicles and large-scale power grids, lithium-ion batteries inevitably face the problem that their limited energy density and high cost cannot meet the growing demand. Room temperature sodium-sulfur (RT Na-S) batteries, which have the potential to replace lithium-ion batteries, have become a focus of attention. However, the challenging problem of their poor cycling performance cause by the “shuttle effect” of the reaction intermediates (sodium polysulfides) needs to be addressed. We report a method to incorporate TiO₂ nano particles into the multichannels of electrospun carbon fibers (TiO₂@MCCFs) to stabilize the sulfur compounds and produce high-performance RT Na-S batteries. The TiO₂@MCCFs were prepared by electrospinning followed by heat treatment, and were infiltrated by molten sulfur to fabricate S/TiO₂@MCCF cathode materials. The addition of the TiO₂ nanoparticles increases the affinity of cathode materials for polysulfides and promotes the conversion of polysulfides to lower order products. This was verified by DFT calculations. A S/TiO₂@MCCF cathode with a S content of 54% has improved electrochemical rate and cycling performance, with a specific capacity of 445.1 mAh g⁻¹ after 100 cycles at 0.1 A g⁻¹ and a nearly 100% Coulombic efficiency. Even at 2 A g⁻¹, the cathode still has a capacity of 300.5 mAh g⁻¹ after 500 cycles. This work provides a new way to construct high performance RT Na-S battery cathodes.