Bifunctional separator with a light-weight coating for stable anode-free potassium metal batteries

The anode-free potassium metal battery (AF-KMBs, N : P = 0 : 1) with liquid electrolyte has been proposed through a separator composite directing strategy. A facile and feasible lithium niobate/Graphene (LiNbO3@G) composite was exploited to modify the glass fiber separator, which can realize high-performance AF-KMBs comprising a configuration of Cu||LiNbO3@G||K0.51V2O5. Due to the ferroelectric and polarization of LiNbO3, a stable solid electrolyte interface (SEI) was steadily formed at the anode interface after preliminary electrochemical activation. Combined with morphology observation and electrochemical characterization, it was proved that potassium was uniformly nucleated and selectively deposited on copper foil without obvious K dendrite. Attributed to the high conductivity of potassium ions and stable SEI, good Coulombic efficiency and long cycle life of the obtained AF-KMBs have been achieved. Consequently, our work demonstrates of great necessity to further explore the high-performance potential of anode-free potassium metal battery.