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

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.