Pinecone biomass-derived hard carbon anodes for high-performance sodium-ion batteries

Hard-carbon is considered as one of the most promising anode materials for sodium-ion batteries (SIBs). Now it is imperative to develop a proper preparation method to obtain hard carbon anode particles with high initial coulombic efficiency and good cycling performance. In this paper, we have successfully prepared high performance hard carbon anodes, by selecting abundant and low-cost pinecones as biomass precursor and optimizing the preparation parameters of pinecone-derived hard carbon (PHC). The microstructure of PHC is studied by X-ray diffraction (XRD), Raman spectroscopy, high-resolution transmission electron microscopy (HRTEM) as well as nitrogen adsorption-desorption isotherm methods. The performance of PHC is highly dependent on the carbonization temperature. Increasing carbonization temperature of pinecone precursor can reduce surface area and thus improve the initial coulombic efficiency. Varying carbonization temperature can also adjust the slope and plateau capacity of PHC, and then regulate the energy density and power characteristics of PHC in battery operation. PHC1400 still delivers a capacity of 334 mA h g(-1) after 120 cycles, with a high initial coulombic efficiency of 85.4%. Our results suggest that PHC is a promising anode material for practical large-scale SIB application.