Stable and fast Na-ion storage of recovered carbon from the spent carbon cathode of aluminum electrolysis

The recovered carbon from aluminum electrolysis is used as the anode for Na-ion battery. It discharges specific capacity of 134 mA h g −1 at current density of 5000 mA g −1 . It gives ∼100% capacity retention after cycled 2000 times under 1000 mA g −1 .