Zn-Ion Batteries: Boosting the Rate Capability and Low-temperature Performance by Combining Structure and Morphology Engineering
Fuxiang Wang, Yanping Li, Wenjing Zhu, Xiuli Ge, Hongtao Cui, Kai Feng, Shanshan Liu, Xin Yang
Abstract
Prussian blue analogues (PBAs) have been considered as one kind of the most promising cathode materials for Zn-ion batteries (ZIBs) due to their low cost, high performance, high safety, and high abundance. However, owing to the low conductivity and single electron reaction, it is a great challenge to obtain a PBA cathode material with high reversible capacity, high rate capability, and good temperature adaptability. Here, a cathode material, K1.14(VO)3.33[Fe(CN)6]2·6.8H2O (KVHCF), with a multielectron reaction and double conductive carbon framework (DCCF) is designed and synthesized by combining structure and morphology engineering. With the multielectron reaction and high electronic conductivity simultaneously, the KVHCF@DCCF cathode material delivers a high specific capacity (180 mAh·g–1 @ 400 mA·g–1) and the best rate performance (116 mAh·g–1 @ 8000 mA·g–1) of the reported PBAs. Moreover, KVHCF@DCCF presents a high specific capacity of 132 mAh·g–1 @ 400 mA·g–1 at 0 °C. Even at −10 °C, it still delivers specific capacities of 127 mAh·g–1 @ 40 mA·g–1 and 80 mAh·g–1 @ 400 mA·g–1 with a retention of 86% after 700 cycles. In situ X-ray diffraction (XRD) and ex situ X-ray photoelectron spectroscopy (XPS) are carried out to investigate the charge–discharge electrochemical reaction mechanism.