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.

Electrochemical activation was used to boost surface- and diffusion-controlled capacitance of MnO₂ by optimized charge–discharge cycling operations.