Lithium metal has a high theoretical capacity of 3860 mA h g−1 and a low electrochemical potential (−3.04 V vs. H2/H+). Hence, using a lithium anode significantly improves the energy density of a secondary battery. However, the lithium dendrites generated on the lithium anode during the plating-dissolution process significantly reduce its cycling life and safety. Here, we provide a simple method for lithium anode protection, by applying a free-standing porous carbon film with a high specific surface area to reduce the local current density and obtain a homogenous ion distribution. The protected lithium anode has a long cycle life over 1000 h when cycled at 3 mA cm−2 with a lithium capacity of 2.5 mA h cm−2. Moreover, the deposited lithium has a smoother surface than Li anode without carbon protection. This study will promote the wide application of Li-metal-based batteries with high safety levels.