▎ 摘　　要

NOVELTY - The method involves: (a) filtering marine biomass precursor; (b) washing squid ink with dilute sulfuric acid, stirring for 12 hours, washing with deionized water for multiple times in centrifuge at a rotating speed of 9000 revolutions/minute, and freeze-drying to obtain precursor product; (c) cell-crushing squid ink and sulfur powder in aqueous solution by using cell crusher, ultrasonically crushing graphene oxide in water to form suspension, mixing two solutions, cell-crushing, and freeze-drying to obtain brown-black powder; and (d) placing brown-black powder into corundum porcelain boat, introducing argon gas in tubular furnace for carbonization treatment, cooling to room temperature, taking-out sample, cleaning with diluted hydrochloric acid solution, and washing with de-ionized water until neutral, and drying to obtain black powder. USE - The method is useful for preparing nitrogen and sulfur co-doped carbon nano-material, which is useful in potassium ion battery. ADVANTAGE - The nitrogen and sulfur co-doped carbon nano-material: has low cost and rich resource, reduces waste of resource; and provides a thought for efficient utilization of marine biological waste. The squid ink: is rich in protein; contains a large amount of nitrogen element; can realize its own element doping during high temperature carbonization process; and improves more active sites and defects for carbon material. Pyridine nitrogen and pyrrolic nitrogen content is high, which is good for adsorption of potassium ion, thus providing high amount of pseudo-capacitance ratio, and giving good potassium storage performance to the material.