The integration of high nickel rich single crystal LiNi0.8Co0.1Mn0.1O2 (SCNCM811) with argyrodite sulfide solid electrolyte (Li6PS5Cl) is crucial for realizing the high-energy density all-solid-state lithium batteries (ASSLBs). However, the development of ASSLBs is hindered by complex issues including unstable cathode-electrolyte interface, detrimental side reactions between high nickel oxide cathodes and argyrodite sulfide solid electrolytes (SSEs). Further oxygen release from cathode surface at higher working voltages during continuous charge/discharge cycles leads to severe cracking of cathodes and undesirable decomposition of SSEs which aggravate the interfacial impedance to lithium-ions. These phenomena contribute to interfacial instability constraints resulting in progressive degradation of electrochemical performance of ASSLBs. Herein, a simple and facile modification approach was employed for the surface modification of SCNCM811 using boric acid (H3BO3) as boron source followed by dry annealing process to facilitate boron surface modification. The proposed coating strategy significantly enhanced the interfacial stability of high performance all-solid-state lithium batteries by constructing a stable interface for smooth lithium-ion diffusion and reduced the degradative side reactions with sulfide solid electrolytes. On these grounds, the modified B-SCNCM811/LPSCl/Li-In all-solid-state lithium batteries exhibited impressive cycling stability with capacity retention of 88.2 % over the course of 50 cycles at 0.5C. Diverse and comprehensive characterizations, combined with galvanostatic intermittent titration technique, electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS) further provided insights for solving the interfacial problems and improved chemical and electrochemical characteristics of ASSLBs.