A “two-pronged” strategy towards dendrite-free potassium metal anodes: Potassiophilic zinc modification synergized with in-situ red phosphorus-derived protective layer

•A novel and effective “two-pronged” strategy for the first time to simultaneously suppress K dendrite growth and in-situ form a dense and robust SEI layer.•The potassiophilic zinc modification can induce uniform deposition of potassium metal to achieved an ultra-long cycle lifespan of 2000 h and an average Coulombic efficiency of 99.23%.•The spontaneous generation of KxPy between the deposited K metal and red phosphorus contributes to the robust SEI layer, which greatly improves the cycling stability of the RP-Cu@Zn-K anode.