Hydrogen‐Bond‐Stabilized Organic Potassium‐Ion Full Cell Operating at −40°C

Low-temperature energy storage systems confront severe operational constraints due to sluggish ion kinetics and electrolyte solidification. While potassium-ion batteries (PIBs) offer potential for low-cost energy storage, the absence of viable cathode materials with adequate stability at ultra-low temperatures remains a critical barrier. Herein, we demonstrate an organic small molecule, 1,4-dihydrobenzo[g]quinoxaline-2,3,5,10-tetraone (BQXTO), in which intermolecular hydrogen bonds (HB) and robust π─π interactions synergistically enhance charge transfer and impart insolubility, thereby facilitating reaction kinetics and improving cycling stability even under low-temperature conditions. The assembled BQXTO||HC potassium-ion full cell achieves remarkable energy density at -40 °C (188 Wh kg^-1) and exceptional cyclability (88.2% capacity retention over 2000 cycles). This study presents valuable insights into the structure design of organic small molecule cathodes for advanced low-temperature PIBs.