Improving the cyclic stability of MoO2 anode for sodium ion batteries via film-forming electrolyte additive

Application of film-forming electrolyte additive has been demonstrated to be an effective and economical approach to improve the performances of lithium ion batteries. However, investigations on the influence of electrolyte additives on the performances of sodium ion batteries is very limited. In this work, with vinylene carbonate (VC) as electrolyte additive, the cyclic stability of MoO2 anode for sodium ion batteries is greatly improved. After 1000 cycles at 300 mAg−1, the capacity retention of MoO2 electrode achieves 96.5% in comparison with that of 20.1% without additive. The poor long-term cyclic performance of MoO2 is mainly ascribed to the sever electrolyte reduction reaction during cycling, which results in significantly increase of electrode polarization. The VC-induced solid electrolyte interphase film effectively suppresses the decomposition of baseline electrolyte, and therefore, hinders the increase of interfacial reaction resistance and improves the interfacial stability of MoO2 electrode.