Corn stalks derived hierarchical porous carbon as ultra-efficient anode materials for sodium-ion batteries

Cornstalk, abundant and recyclable biomass, is converted into a porous material by a chemical treatment with KOH and Ni(NO3)2. The resulting material possesses a surface area equal to 2150 m2 g−1, delivers 1.56 cm3 g−1 of the total pore volume and contains 0.62% of nitrogen. The presence of Ni2+ improves the graphitization degree and the surface area of the materials. This unique porous carbon-based material is incorporated into sodium-ion batteries, which demonstrate excellent initial reversible capacity (439 mAh g−1 at 0.1 A g−1), high-rate ability (132 mAh g−1 at 5 A g−1), and long-term cycling stability (221 mAh g−1 after 200 cycles at 0.1 A g−1). Overall, this work provides a straight-forward and inexpensive approach to fabricate high performance anodes for sodium-ion batteries.