Amorphous\nAlOCl Compounds Enabling Nanocrystalline\nLiCl with Abnormally High Ionic Conductivity

LiCl\nis a promising solid electrolyte, providing it possesses high\nionic conductivity. Numerous efforts have been made to enhance its\nionic conductivity through aliovalent doping. However, aliovalent\nsubstitution changes the intrinsic structure of LiCl, compromising\nits cost-effectiveness and electrochemical stability. Here, we report\nnanocrystalline LiCl embedded in amorphous AlOCl compounds with a\nheterogeneous structure to enhance its ionic conductivity. Nanocrystallization\nenlarges the LiCl unit cell, while amorphization facilitates interfacial\nion transport. As a result, the amorphous AlOCl-modified LiCl nanocrystal\n(AlOCl-nanoLiCl) demonstrates a high ionic conductivity of 1.02 mS\ncm<sup>–1</sup>, which is 5 orders of magnitude higher than\nthat of LiCl. Additionally, it exhibits high oxidative stability,\nlow cost ($19.87 US kg<sup>–1</sup>), and low Young’s\nmodulus (2–3 GPa). When AlOCl-nanoLiCl is coupled with Li-rich\ncathodes (Li<sub>1.17</sub>Mn<sub>0.55</sub>Ni<sub>0.24</sub>Co<sub>0.05</sub>O<sub>2</sub>, 4.8 V vs Li<sup>+</sup>/Li), all-solid-state\nbatteries exhibit remarkable long-term cycling stability (>1000\ncycles).\nThis work presents a novel strategy to enhance the ionic conductivity\nof alkaline chlorides without compromising their intrinsic advantages.