The synthesis of solid electrolytes with high ionic conductivity and the design of electrode interface with preferable compatibility are critical to realize the bulk-type application of all-solid-state batteries. In order to realize the superior electrochemical performance, argyrodite Li6PS5Cl is a promising solid electrolyte in all-solid-state batteries due to high ionic conductivity and electrochemical stability. Meanwhile, the solution reprecipitation is a valid process providing intimate ionic contact between electrodes and electrolytes to mitigate the interface incompatibility. Here, a wet-slurry process by dispersing active material (LiNi0.8Co0.1Mn0.1O2), solid electrolyte (Li6PS5Cl), binder (ethyl cellulose) and conductive additives (carbon black) in anhydrous ethanol is developed to fabricate cathode. The effect of different contents of the binder in the composite cathodes on the electrochemical performance is investigated. The all-solid-state battery with a composite cathode containing 1 wt% of ethyl cellulose shows a reversible discharge capacity of 111.7 mAh g−1 at 30 °C and its capacity retention is approximately 89.7% after 100 cycles. This work demonstrates that the fast ion migration and stable interface between active particles and solid electrolyte enabled by optimum content of chemically compatible binder are critical to the electrochemical performance of all-solid-state lithium-ion batteries.