Robust 3D Copper Foam Functionalized with Gold Nanoparticles as Anode for High-Performance Potassium Metal Batteries.

As a possible anode for the next generation of electrochemical energy storage batteries, potassium metal has attracted a great deal of attention in recent years. However, potassium metal batteries suffer from poor stability and low coulombic efficiency due to unfavorable dendrite growth and severe volume expansion of potassium metal anodes during charge and discharge processes. Here, a strategy is developed to inhibit dendrite growth, reduce volume expansion and improve the stability of the potassium metal anode by using three-dimensional (3D) copper foam chemically loaded with a thin layer of uniform gold particles (Au/Cu) as the anode substrate. As the host of potassium deposition for forming K/Au/Cu foam anode, such a 3D copper foam with large specific surface area can reduce the potassium deposition current density. The gold particles on the Cu foam surface with a good affinity to potassium can reduce the potassium deposition overpotential, provide deposition sites and realize uniform and dense deposition. As a result, a stable cycle of more than 500 cycles is achieved by using such a K/Au/Cu foam anode. A full cell with K/Au/Cu foam anode and Prussian blue cathode delivers much better coulombic efficiency, cycle stability and low-temperature performance when compared to that without gold deposition anode (K/Cu). Both the experimental characterization for material structure/morphology/composition and theoretical DFT calculations are carried out for fundamental understanding of the performance enhancement mechanism. The main advantages of this 3D K/Au/Cu foam are its potassiophilicity and less volume expansion during charge/discharge processes, which can reduce or eliminate the potassium dendrite growth through forming favorable and stable solid electrolyte interface.