Synthesis of Mesoporous Carbon Using Waste Orange Peel As an Anode Material for Potassium-Ion Batteries with Long Cyclability

Abstract

Potassium‐ion batteries (PIBs) have been considered as the most promising candidate due to their low cost and high safety to replace the Li-ion batteries. However, current graphite anode cannot encounter the demands for high storage capacity and low cost, which are required for the commercial PIBs. Thus, it is needed to discover porous carbon anode material with high capacity, longer cycle life, low cost, and environment friendless for PIBs. Porous carbon is regarded as an attractive anode material for PIBs due to its high conductivity, chemical stability, and expanded interlayer spacing, which can helpful to accommodate more K-ions. In particular, biomass derived porous carbon has the advantages as a renewable and low cost carbon source. It can also provide excellent 3-D porous nanostructure for high storage capacity and long cyclability in batteries. Among the biomass wastes, 15.6 million tons of orange peel is discarded every year. It may be very useful if we can use these wastes as a resource for an electrode of batteries. Orange peel is mainly composed of cellulose, hemicellulose, lignin, and pectin, which are known as excellent carbon precursors. In this study, we fabricated mesoporous carbon from orange peel through a facile one step carbonization approach without introducing extra activation agents. The mesoporous carbon displayed the first discharge and charge capacities of 408 and 224 mAh g-1, respectively, corresponding to a Coulombic efficiency of 55%. Even after 100 cycles, the electrode maintained a high capacity 210 mA g-1. When the specific current is further increased to 200 mA g-1, the high specific capacity of 150 mA g-1 was still achieved, which corresponds to a capacity retention of 80% after 2000 cycles. This superior cycling stability is attributed to the improved ionic diffusion kinetics and electronic conductivity resulting from the mesoporous structure and large interlayer spacing. Furthermore, a full cell composed of mesoporous carbon anode and potassium Prussian blue cathode displayed an adequate electrochemical performance.