Alumina thin coat on pre-charged soft carbon anode reduces electrolyte breakdown and maintains sodiation sites active in Na-ion battery – Insights from NMR measurements

Abstract Atomic deposition of a thin layer of alumina on amorphous carbon materials was recently established to improve their electrochemical properties as anodes in sodium-ion batteries. It is shown that the highest performance for these materials can be achieved by pre-sodiation of the electrode before coating it. The basis for the enhanced performance is illuminated by 13C and 23Na MAS NMR analysis showing that this specific procedure diminishes parasitic reactions and preserves reversible access to active sodiation sites.