Finding Suitable Discharge Potential and Effect of Succinic Anhydride as Electrolyte Additive on MoS2/Carbon Composites for Efficient and Stable Sodium Ion Battery Anode.

Abstract

A series of MoS2/C composites are synthesized for SIB anode by changing sulfur sources using a facile hydrothermal and ball milling strategy. The carbon modification increases the conductivity and minimizes volume expansion of the material. The intercalation potential was find out for MoS2/C composites by several electrochemical and ex-situ XRD measurements. The MoS2-NS/C, MoS2-Tu/C, and MoS2-S/C electrodes deliver ~312, 304 and 293 mAh/g reversible capacities at 50 mA/g current densities between 0.3-2.5 V. The different reversible capacities of MoS2/C composites could be due to the different surface areas or morphologies of the composites. We also demonstrate the effect of succinic anhydride (SA) as electrolyte additive in cyclic stabilities, which shows an increment of (~60% to ~76%) capacity retention with SA addition. The ex-situ XPS and TEM analysis revealed that more Na2CO3 rich SEI was formed in presence of SA. The SA-derived SEI also prevents the NaPF6 degradation, thereby increases the cyclic performance. Furthermore, the full cells assembled with MoS2/C (anode) and Na3V2(PO4)3 (cathode) shows ~280 mAh/g specific capacity at 0.05 A/g based on active mass of anode. The improved Na+ storage performance is attributed to the fast Na+ intercalation, improved conductivity and stable SEI formation during charge/discharge.