Rechargeable lithium–metal batteries with a cell‐level specific energy of >400 Wh kg−1 are highly desired for next‐generation storage applications, yet the research has been retarded by poor electrolyte–electrode compatibility and rigorous safety concerns. We demonstrate that by simply formulating the composition of conventional electrolytes, a hybrid electrolyte was constructed to ensure high (electro)chemical and thermal stability with both the Li‐metal anode and the nickel‐rich layered oxide cathodes. By employing the new electrolyte, Li∥LiNi0.6Co0.2Mn0.2O2 cells show favorable cycling and rate performance, and a 10 Ah Li∥LiNi0.8Co0.1Mn0.1O2 pouch cell demonstrates a practical specific energy of >450 Wh kg−1. Our findings shed light on reasonable design principles for electrolyte and electrode/electrolyte interfaces toward practical realization of high‐energy rechargeable batteries. Formulation of conventional electrolyte composition yields a hybrid solid/liquid electrolyte that is electrochemically compatible with the Li‐metal anode and the nickel‐rich layered oxide cathodes, which promises stable operation of a practical 10‐Ah‐grade pouch cell with a specific energy of >450 Wh kg−1.