Synergistic halide-sulfide hybrid solid electrolytes for Ni-rich cathodes design guided by digital twin for all-solid-State Li batteries

Halide solid electrolytes are a promising candidate for all-solid-state Li batteries (ASLBs) owing to their mechanical sintering ability and excellent (electro)chemical oxidation stability. However, these advantages are counteracted by the lower Li+ conductivities and higher specific densities compared with those of sulfides. Herein, a novel halide-sulfide hybrid catholyte design for Ni-rich layered oxide cathodes for ASLBs is reported. In a hybrid catholyte, Li3YCl6 (0.40 mS cm−1) coatings protect the surface of Li[Ni0.88Co0.11Al0.01]O2 while Li6PS5Cl (1.80 mS cm−1) serves as a Li+ highway. Li[Ni0.88Co0.11Al0.01]O2 cathodes with an optimal fraction of Li3YCl6, 10 wt% with respect to Li [Ni0.88Co0.11Al0.01]O2, substantially outperform electrodes using either Li6PS5Cl or Li3YCl6 in terms of capacity (202 vs. 171 or 191 mA h g−1 at 0.1C, respectively), initial Coulombic efficiency, rate capability, and cycling performance. The superiority of Li3YCl6 for interfacial stability in the Li3YCl6-coated electrode to the electrode without Li3YCl6 is confirmed by complementary analysis. Moreover, the digital twin model is successfully established and reveals electrically isolated Li[Ni0.88Co0.11Al0.01]O2 particles when 14 wt% Li3YCl6 is used. This insight leads to the development of a mixed conductor coating consisting of Li3YCl6 and carbon, further enhancing the performance: e.g., 134 vs. 53 mA h g−1 at 2C.