Efficient honeycomb–shaped biochar anodes for lithium-ion batteries from Eichhornia crassipes biomass

Converting waste biomass into biochar is a means for solving both environmental pollution and energy shortage. Here we transformed Eichhornia crassipes, a harmful floating plant, into a honeycomb-shaped and heteroatoms-rich biochar by KOH activation during carbonization, and we tested this biochar as anode for lithium-ion batteries. Results show that the biochar has a high surface area of 278.56 m2·g−1, a honeycomb-like porous structure, and is rich in heteroatoms, e.g., 3.42% N, 20.82% O, and 0.83% S. Biochar anodes displayed a higher initial reversible specific capacity of 697 mAh·g−1 at 50 mA·g−1, a higher rate capability of 229.7 mAh·g−1 at 3000 mA·g−1, and a better cyclic stability than commercial graphite. The enhanced electrochemical performance could be attributed to the interconnected porous structure that promotes Li+ transfer and electrolyte infiltration, and to the presence of heteroatoms. This approach can be easily industrialized as a substitute of graphite.