Excellent performance single-crystal NCM cathode under high mass loading for all-solid-state lithium batteries

•Single-crystal LiNi0.6Mn0.2Co0.2O2 is used as the cathode for ASSLBs.•LiNbO3 is coated on the surface of SC-NCM622 to suppress the interfacial side reactions with SSEs.•SC-NCM622@LNO cathode displays a high discharging capacity of 175.7 mAh g−1 and outstanding cycling performance.•SC-NCM622@LNO with high mass loading presents a remarkable area capacity of 4.0 mAh cm−2. Ni-rich layered cathodes have drawn significant attention for sulfide-based all-solid-state lithium batteries (ASSLBs) owing to high specific capacity and high working potential. However, single-crystal Ni-rich layered cathodes are rarely reported in ASSLBs using sulfide solid electrolytes (SSEs) so far. Herein, single-crystal LiNi0.6Co0.2Mn0.2O2 (SC-NCM622) is used as the cathode for ASSLBs. Furthermore, LiNbO3 is coated on the surface of SC-NCM622 (SC-NCM622@LNO) as the buffer layer to suppress interfacial side reactions with SSEs. Combining the advantages of single-crystal structure and the buffer layer, SC-NCM622@LNO cathode displays a high discharge capacity of 175.7 mAh g−1 with initial Coulombic efficiency of 88.7% at 0.1 C (0.2 mA cm−2) and outstanding cycling performance with a good capacity retention of 91.3% after 100 cycles at a high current density of 1.0 mA cm−2 at 40 °C, far exceeding the reported counterparts. Moreover, SC-NCM622@LNO with high mass loading of 23.2 mg cm−2 still displays excellent electrochemical performance under a higher current density and presents a remarkable area capacity of 4.0 mAh cm−2. This work illustrates that single-crystal Ni-rich cathodes with modified interface could enable high performance ASSLBs. [Display omitted]