A hydrophilic-Zn 2+ conductive lanthanum phosphate interlayer toward ultra-long-life Zn anodes and zinc ion capacitors

The detrimental interfacial side reactions and irregular Zn dendrites may reduce the cycling life of Zn anodes and Zn-based energy storage devices. Regulating the interfacial microenvironment to eliminate harmful side reactions and achieve uniform Zn deposition is vital to develop high-performance Zn anodes. Here, a “hydrophilic-Zn 2+ conductive” lanthanum phosphate (LaPO 4 ) interlayer is applied to realize an ultra-long-life Zn anode (LAP-Zn) and Zn 2+ capacitors. The hydrophilic LaPO 4 can act as a microscopic “H 2 O-reservoir” by preferentially adsorbing H 2 O molecules (the adsorption energy of LaPO 4 –H 2 O is −1.17 eV, larger than that of Zn–H 2 O). Consequently, a microscopic H 2 O-poor environment on the Zn anode is formed, thus eliminating harmful side reactions including H 2 evolution and Zn corrosion. Simultaneously, Zn 2+ de-solvation is promoted, facilitating accelerated interfacial migration and uniform flux of Zn 2+ . The Zn 2+ migration number of LAP-Zn is 0.84 which is higher than that of pure Zn, demonstrating excellent Zn 2+ conductivity. The LAP-Zn//LAP-Zn symmetrical cell operates efficiently for over 700 h at 5 mA cm −2 and 2 mA cm −2 . The LAP-Zn//activated carbon capacitor exhibits an ultra-long life of 30 000 cycles at 1 A g −1 , with continuous operation for over 3600 h while maintaining a capacity retention ratio of 95%. Therefore, this “hydrophilic-Zn 2+ conductive” LaPO 4 interlayer enables uniform Zn deposition and a highly reversible Zn plating/stripping process. This modification strategy using a “hydrophilic-Zn 2+ conductive” rare earth-based interfacial layer is simple, long-term effective, and microcosmic, thus boosting the commercial application of Zn-based energy storage devices.