Carbon Nanosheet Frameworks Derived from Pine Cone Shells as Sodium-Ion Battery Anodes

Abstract

As a kind of green, environment-friendly and sustainable carbon material, biomass carbon has simple processing technology and undoubtedly been the best candidate for industrialization. Different activation processes can be used to change the internal microstructure of carbons, and design pores that facilitate ions transport and electrons conduction, thereby achieving the ultimate goal of improving electrochemical performance. Herein, we select the same activator (KOH) and activation time (3 h) but change the activation temperature (300 °C, 600 °C, 800 °C) to obtain biomass-derived carbon with the different micromorphology, pores structure and heteroatoms content. Rather, We choose ether-based electrolyte, due to its highly reversible graphite co-intercalation reaction, the problem of extremely low electrochemical activity of graphite in ester electrolytes is avoided. Results indicate, the sample PCS-600 exhibites sheet structure with specific surface area of 38.3 m2/g and large average pore width of 2.77 nm, which providing sufficient conditions for ions transport. PCS-600 has 1.05 at% N and 5.75 at% O heteroatoms, which providing additional pseudocapacitance. In addition, the electrochemical performance of PCS-600 is optimal, at a current density of 0.1 A/g, its specific capacity is 198.6 mA h/g, maintain at ~95% after 100 cycles, with coulomb efficiency ~100%.