WS2 Composites with Chitosan Derived Hard Carbon as High-Performance Negative Electrode Material for Sodium-Ion Batteries

The poor electrochemical performance of pristine WS₂ is mainly due to its low conductivity which restricts the redox kinetics. Enhancement in the electrochemical performance of WS₂ as negative electrodes in sodium ion battery (SIB) has been attempted by forming composites with hard carbon (HC) derived from the linear polysaccharide biopolymer chitosan. It is observed that assembling of WS₂ nanostructures on N/O (nitrogen/oxygen) heteroatom loaded hard carbon sheet derived from the biowaste chitosan improves the conductivity, reduces polysulfide leaching, and balances the inherent drawback of volume alteration in the negative electrodes. The electrochemical performance of the WS₂@HC electrodes is investigated by electrochemical impedance spectroscopy measurements. This work establishes that the heteroatom loaded hard carbon support provides mechanical stability and can improve the cycling stability and rate capability of WS₂ by enhancing ion diffusion kinetics.