Lithium metal based battery has high theoretical capacity and high energy density, ideal for large-scale energy storages such as in electric vehicles. However, dendritic deposition of lithium metal, which is especially severe at high current charging, causes serious safety problems. Previously, we reported in-situ formation of a single-component coating of crystalline lithium methyl carbonate (LMC) and stable cycling of lithium metals (ACS App. Mater. Interface, 2017, 30635). Here we extend the methodology and report a polymer gel coating on lithium metal surface formed in-situ from a pure vinylene carbonate (VC) solution . The polymerization rate of VC can be controlled by time, temperature, and the initiator, which resulted in a stable polymer gel. The mechanically robust gel can be used directly as an electrolyte layer in battery cells. Remarkably, the Li/Li cell cycled for 1000 hours without increase of resistance at a current density of 5 mA cm⁻². A dense layer of lithium metal was observed at the interface of lithium and the gel, which indicated the stabilization of lithium metal by the polymer gel. The chemical structure of the polymer was analyzed by infrared spectroscopy and ¹H NMR and evaluated as poly (vinylene carbonate) (polyVC) with a partially branched structure. The polymerization step is proposed to occur in a living radical fashion. The formation of electrolyte layers through in-situ polymerization is a promising approach to stabilize lithium metal electrodes.