Hierarchically porous carbon derived from wheat straw for high rate lithium ion battery anodes

Porous biochar for anode material of lithium ion battery (LIBs) was prepared from wheat straw, one of the most common biomass of agricultural waste in China, with KOH using as activator. Microstructure of the porous biochar was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) as well as Brunauer–Emmett–Teller (BET). The porous biochar prepared contains parallel microporous channels derived from wheat straw. These microchannel structures offer the advantage of facilitating the transport of electrolyte ions and providing more active sites. Meanwhile, the electrochemical properties were investigated by galvanostatic charge–discharge (GCD) curves, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The specific capacitance of biomass carbon activated by KOH reaches 271.7 F g⁻¹ at scanning rate of 1 mv s⁻¹. After 100 cycles at 0.1 °C rate, the discharge capacity of lithium-ion battery prepared is 310 mA h g⁻¹, which shows that the material has good rate performance and cycle stability. The samples prepared by this method have a rich pore structure, can improve the permeability of electrolyte, increase the reactive sites, and increase the free movement space of lithium ions and charges, which is conducive to the improvement of electrochemical properties.