The theoretical basis and battery structure of sodium ion battery (Na-ion batteries) and lithium ion battery are very similar. Liquid sodium-ion batteries (like solid-state lithium-ion batteries, are also being investigated) are composed of positive electrode, negative electrode, current collector, electrolyte, and battery separator. 

Among them, electrolyte and separator basically follow the lithium ion battery system; Aluminum foilcan be used for both anode and cathode of the current collector, while copper foil is needed for the anode of the lithium-ion battery (because sodium ions do not react with aluminum ions at the anode), which also reduces the cost of thecurrent collector.