Dipotassium terephthalate as promising potassium storing anode with DFT calculations

We report combined experimental and theoretical studies of dipotassium terephthalate as anode material for K-ion battery application. Both pristine and carbon nanotube-containing dipotassium terephthalate materials are synthesized using an ultrafast microwave-assisted method. We found that carbon nanotube (CNT)-containing dipotassium terephthalate composite electrode delivers an initial reversible capacity of 247 mAh/g with 78% capacity retention, whereas pristine K₂Tp deliveries an initial reversible capacity of 212 mAh/g with 53% capacity retention at the end of 100 cycles, at a current density of 50 mA/g. The density functional theory-based calculations have shown superior stability of dipotassium terephthalate lattice against the intercalation of potassium atoms. The quantum calculations are also employed to unravel the specifics of intercalation energetics of potassium ions into dipotassium terephthalate lattice. The intercalation and de-intercalation potentials of K-ions are obtained using cyclic voltammetry and compared with theoretical calculations under the assumption of a two-electron transfer reaction. The results of this study lay the ground for understanding the electrochemical processes involved in the operation of an organic anode in K-ion batteries, and thereby can facilitate the design of optimal organic molecular crystal-based electrode materials for battery applications.