First, we synthesized nano-crystalline LIC by high-energy ball milling with an average grain size of nano-scale level and a total conductivity of 1.44 mS/cm after a subsequent annealing step at 300 °C. Thereafter, the LIC was coated around NCA particles by a scalable and economically efficient coating process using mechanofusion. Based on mechanofusion, not only a surface smoothing of NCA particles but also a homogeneous and thin coating of about 150 nm, has been achieved. Finally, solid-state batteries have been assembled with NCA w/wo LIC coating and tested with respect to their cyclability under different C-rates. It is shown that the LIC coating increases the performance at any C-rate at about 80 mAh/g at all C-rates. For example, at 0.1C the discharge capacity reaches a value as high as 148.3 mAh/g compared to 71.8 mAh/g when no coating has been established. Long-cycling tests shows stable long-term cycling with 80.1% capacity retention after 200 cycles under 0.2C compared to SSB-NCA with around 40 mAh/g. The improved performance has been identified to be related to absence of interfacial decomposition reactions of LPSCl, interfacial delamination, and particle cracking, as observed for uncoated NCA-based SSBs. This study demonstrates that (i) LIC is a promising stable solid electrolyte for coating HV cathodes to enable sulfide-based SSBs when appropriate conditions have been chosen, as well as (ii) that mechanofusion is a viable, easy, and universal technique for coating spherical-shaped cathode materials by complex compounds, which can play a pivot role in the materials development and their scaling, to enable widespread adoption of future solidstate batteries.