The instability of lithium (Li) metal anodes due to dendritic growth and low Coulombic efficiency (CE) hinders the practical application of high‐energy‐density Li metal batteries. Here, the systematic studies of improving the stability of Li metal anodes and the electrochemical performance of Li metal batteries through the addition of combinational additives and the optimization of solvent compositions in dual‐salt/carbonate electrolytes are reported. A dendrite‐free and high CE of 98.1% for Li metal anode is achieved. The well‐protected Li metal anode and the excellent cyclability and rate capability of the 4‐V Li metal batteries are obtained. This is attributed to the formation of a robust, denser, more polymeric, and higher ionic conductive surface film on the Li metal anode via the electrochemical reductive decompositions of the electrolyte components and the ring‐opening polymerization of additives and cyclic carbonate solvents. The key findings of this work indicate that the optimization of solvent compositions and the manipulation of additives are facile and effective ways to enhance the performances of Li metal batteries. Dendrite‐free and high Coulombic efficiency of 98.1% for Li metal anode are achieved via a facile approach of optimizing solvent compositions and adding combinational additives in LiTFSI‐LiBOB/carbonate electrolytes. The excellent cyclability and rate capability of 4‐V Li metal batteries are attributed to the formation of a robust, denser, more polymeric, and higher ionic conductive surface film on the Li metal anode.