Lattice‐Interface Dual Engineering Unlocking Quasi‐Zero‐Strain and High‐Rate Zinc‐Ion Storage in Polyanionic Cathode

ABSTRACT The advancement of aqueous zinc‐ion batteries is hindered by the performance of cathode. Na 3 V 2 O 2 (PO 4 ) 2 F has attracted increasing attention for its advantages, including a high voltage plateau, large ion diffusion channels, and outstanding structural stability. However, its inadequate electronic conductivity causes undesired cycling performance and rate capability. In this work, a microwave hydrothermal‐assisted high‐temperature calcination has been utilized to obtain Li‐doped Na 3 V 2 O 2 (PO 4 ) 2 F coated with N‐doped carbon (N 2.85 L 0.15 VOPF@NC). Theoretical calculations and experimental data demonstrate that the co‐modification of Li doping and carbon coating results in favorable morphological integrity, increased electronic conductivity, reduced Zn 2+ migration barrier, and high average Zn 2+ diffusion coefficient, contributing to superior electrochemical properties. N 2.85 L 0.15 VOPF@NC exhibits a significantly enhanced performance with reversible capacities of 151.9 and 47.2 mAh g −1 at 0.5 and 5 A g −1 over 80 and 4,000 cycles, respectively. The soft package batteries also exhibit a stable reversible capacity of 56.4 mAh g −1 after 700 cycles. In situ electrochemical impedance spectroscopy uncovers the lattice strain release as an intrinsic factor in capacity enhancement, facilitating the ionic and electrical diffusion processes. In situ X‐ray diffraction, ex situ X‐ray photoelectron spectroscopy, and transmission electron microscopy account for the quasi‐zero‐strain behavior (volume change rate of 1.04%) and the reversible Zn 2+ insertion/extraction mechanism.