Unlocking Fast Potassium Ion Kinetics: High-Rate and Long-life Potassium Dual-ion Battery for Operation at -60℃.

Abstract

Energy storage devices operating at low temperatures are plagued by sluggish kinetics, reduced capacity, and notorious dendritic growth. Herein, novel potassium dual-ion batteries (PDIBs) capable of superior performance at -60°C, and fabricated by combining MXenes and polytriphenylamine (PTPAn) as the anode and cathode, respectively, are presented. Additionally, the reason for the anomalous kinetics of K+ (faster at low temperature than at room temperature) on the Ti3C2 anode is investigated. Theoretical calculations, crossover experiments, and in-situ XRD at room and low temperatures revealed that K+ tends to bind with solvent molecules rather than anions at subzero temperatures, which not only inhibits the participation of PF6- in the formation of the solid electrolyte interphase (SEI), but also guarantees co-intercalation behavior and suppresses undesirable K+ storage. The advantageous properties at low temperatures endow the Ti3C2 anode with fast K+ kinetics to unlock the outstanding performance of PDIB at ultralow temperatures. The PDIBs exhibit superior rate capability and high capacity retention at -40°C and -60°C. Impressively, after charging-discharging for 20,000 cycles at -60°C, the PDIB retained 86.7% of its initial capacity. This study reveals the influence of temperatures on MXenes and offers a unique design for dual-ion batteries operating at ultralow temperatures.