Biocarbon with different microstructures derived from corn husks and their potassium storage properties

Abstract In this paper, biocarbon was prepared from corn husks as anode materials for potassium ion batteries at temperatures ranging from 700 to 1600 °C. The prepared biocarbon materials have amorphous phase structure and possess larger interlayer spacing than graphite. The biocarbon exhibits enhanced graphitic degree and decreased amounts of surface defects, while the carbonization temperature gradually increases. The obtained potassium ion battery electrode at 1300 °C acquired high reversible capacity up to 216.6 mAh·g −1 at 0.1 A·g −1 after 100 cycles, and retained 128.6 mAh·g −1 at 1 A·g −1 even after 500 cycles. The results indicate that the samples prepared at 1300 °C have better electrochemical performance than other samples prepared at different temperatures, which was attributed to the decisive influence of microstructure on surface‐induced and intercalating potassium storage.