Halide solid-state electrolytes are critical for developing high-safety, high-energy-density all-solid-state lithium batteries. However, most existing synthesis methods for halide electrolytes rely on non-equilibrium strategies, which struggle to simultaneously achieve high ionic conductivity and good stability. Here, we propose a facile one-step solid-state route that constructs a highly conductive and structurally robust crystalline-amorphous core-shell heterostructure by aliovalent doping of Hf4 +/Zr4+ into Li3YCl6. In this heterostructure, the ordered crystalline core serves as a robust scaffold, while nanocrystallites that simultaneously promote structural integrity and ion transport are embedded within the continuous, highly conductive amorphous shell. These structural features synergistically establish a three-dimensional ion migration network with low transport barriers and high connectivity, enabling Li2.6Y0.6Hf0.4Cl6 to achieve a room-temperature ionic conductivity of 1.4 mS·cm−1, a 37-fold enhancement over the pristine phase, and an activation energy of 0.30 eV. Benefiting from its excellent interfacial stability against Li–In anode, all-solid-state batteries employing the LiNi0.8Mn0.1Co0.1O2 cathode operate stably without a sulfide interlayer, achieving 80.8% capacity retention after 200 cycles at room temperature and 73.8% retention after 100 high-rate cycles at elevated temperature. With an additional sulfide interlayer to further optimize the interface, the cell delivers a prolonged cycle life with 87.2% capacity retention over 580 cycles. Through a straightforward solid-state doping approach, this work designs a highly conductive and structurally stable halide electrolyte, offering a new design paradigm for halide electrolytes.
