NaTi2(PO4)3 Solid‐State Electrolyte Protection Layer on Zn Metal Anode for Superior Long‐Life Aqueous Zinc‐Ion Batteries

Abstract

AbstractA fast ion conductor, NaTi2(PO4)3 (NTP), is hydrothermally synthesized as a solid‐state electrolyte protection layer on the surface of Zn anodes (NTP@Zn). NTP has fast ionic conductivity compared with other insoluble phosphates, such as TiP2O7 (TPO) and Zn3(PO4)2 (ZPO), which is demonstrated by the density‐functional theory calculation and cyclic voltammetry tests. X‐ray photoelectron spectrometer, X‐ray powder diffraction, and HRTEM analyses show that the internal transport/mobility of Zn2+ can be achieved in NTP layer as an “ion passable fence.” The NTP layer with a thickness of 20–25 µm not only prevents side reactions and zinc dendrites, but also improves the reversibility of Zn deposition and electrochemical performance. The NTP@Zn/MnO2 battery represents the best long‐life performance among Zn/MnO2 batteries to date, which successfully retains a considerable capacity of 105 mA h g−1 with a CE nearly 100% after 10 000 charge/discharge cycles at 10 C (≈1.5 A g−1). Each cycle capacity attenuation rate is only 0.004%. This work represents an advanced step toward long‐life Zn metal anodes for aqueous zinc‐ion batteries.