Unravelling the impact of electrolyte nature on Sn4P3/C negative electrodes for Na-ion batteries

Carbon coated tin phosphide is synthesized by an easily scalable ball milling method. The electrochemical performance of Sn4P3/C electrodes is explored using different combinations of carbonate and ether-based solvents. Our experiments reveal that a remarkable improvement in the specific charge of Sn4P3 anodes can be obtained by using a combination of NaPF6 salt and diethylene glycol dimethyl ether electrolyte. A reversible specific charge of 900 mA h g(-1) and initial coulombic efficiency of around 90% have been achieved. We carefully examine the origin of the improved capacity and cycle life when using glyme-based electrolytes and compare with carbonate electrolytes. Moreover, the reaction mechanism of the Sn based anode is further discussed.