Reversible Oxygen-Rich Functional Groups Grafted 3D Honeycomb-Like Carbon Anode for Super-Long Potassium Ion Batteries

Studies have found that oxygen-rich-containing functional groups in carbon-based materials can be used as active sites for the storage performance of K(+), but the basic storage mechanism is still unclear. Herein, we construct and optimize 3D honeycomb-like carbon grafted with plentiful COOH/C = O functional groups (OFGC) as anodes for potassium ion batteries. The OFGC electrode with steady structure and rich functional groups can effectively contribute to the capacity enhancement and the formation of stable solid electrolyte interphase (SEI) film, achieving a high reversible capacity of 230 mAh g(−1) at 3000 mA g(−1) after 10,000 cycles (almost no capacity decay) and an ultra-long cycle time over 18 months at 100 mA g(−1). The study results revealed the reversible storage mechanism between K(+) and COOH/C = O functional groups by forming C-O-K compounds. Meanwhile, the in situ electrochemical impedance spectroscopy proved the highly reversible and rapid de/intercalation kinetics of K(+) in the OFGC electrode, and the growth process of SEI films. In particular, the full cells assembled by Prussian blue cathode exhibit a high energy density of 113 Wh kg(−1) after 800 cycles (calculated by the total mass of anode and cathode), and get the light-emitting diodes lamp and ear thermometer running. [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40820-022-00892-8. ARTICLE HIGHLIGHTS: A 3D honeycomb-like carbon grafted with plentiful COOH/C = O functional groups (OFGC) is constructed and optimized. The study results revealed that the grafting of COOH/C = O functional groups increased specific capacity by forming a C-O-K compound with K, and this reaction is highly reversible. The OFGC as anode for potassium-ion batteries achieved a high reversible capacity of 230 mAh g(−1) after 10,000 cycles (almost no capacity decay) at 3000 mA g(−1) and an ultra-long stable cycle time over 18 months at 100 mA g(−1).