Perylenetetracarboxylic diimide as a high-rate anode for potassium-ion batteries†
Organic compounds are appealing electrode materials for potassium-ion batteries (PIBs) owing to their economical and eco-friendly nature. Here, we report an important organic semiconductor, 3,4,9,10-perylenetetracarboxylic diimide (PTCDI), as a high-rate anode for PIBs. The PTCDI electrode is found to deliver a high average specific capacity of 310 mA h g−1 at 0.5 A g−1 and a remarkable rate performance (in the range from 0.5 to 5.0 A g−1), which can be attributed to the fast K ion diffusion (up to ∼10−8 cm2 s−1) and low charge-transfer resistance (93 ohm). The proposed six-electron storage mechanism for the PTCDI electrode during the discharge/charge process has been revealed by ex situ infrared (IR) spectroscopy and ex situ X-ray diffraction (XRD), as well as density functional theory (DFT) calculations. This study could pave the way for developing advanced PIB anodes with low cost and high performance.