Quinone Electrode for Long Lifespan Potassium-Ion Batteries Based on Ionic Liquid Electrolytes.

As a class of flexible and designable materials, organic electrode materials would greatly facilitate the progress of potassium-ion batteries (PIBs), especially when the dissolution issue is ameliorated. Ionic liquid electrolytes (ILEs) do not merely alleviate the dissolution of organic materials but provide reliable security. Herein, Pillar[5]quinone (P5Q) as the cathode of PIBs is demonstrated for the first time, and the electrochemical performance of two common ILEs is investigated. In the 0.3 M KFSI-PY13FSI electrolyte with better conductivity, the P5Q cathode maintains a large reversible capacity of 232 mAh g (450 Wh kg) after 100 cycles at 0.2C at 1.2-4.0 V. When a current density of 2.0C is applied, the cell retains a capacity of 101 mAh g (211 Wh kg) after 1000 cycles and 61 mAh g (125 Wh kg) even over 5000 cycles. This research would inspire research on organic electrodes and advance the application of PIBs.