Lithium-carbon dioxide (Li-CO 2 ) batteries have received wide attention due to their high theoretical energy density and CO 2 capture capability. However, this system still faces poor cycling performance and huge overpotential, which stems from the leakage/volatilization of liquid electrolyte and instability of the cathode. A gel polymer electrolyte (GPE)-based Li-CO 2 battery by using a novel pencil-trace cathode and 0.0025 mol L −1 (M) binuclear cobalt phthalocyanine (Bi-CoPc)-containing GPE (Bi-CoPc-GPE) is developed here. The cathode, which is prepared by pencil drawing on carbon paper, is stable because of its typical limited-layered graphitic structure without any binder. In addition, Bi-CoPc-GPE, which consists of polymer matrix filled with liquid electrolyte, exhibits excellent ion conductivity (0.86 mS cm −1 ), effective protection for Li anode, and superior leakproof property. Moreover, Bi-CoPc acts as a redox mediator to promote the decomposition of discharge products at low charge potential. Interestingly, different from polymer-shaped discharge products formed in liquid electrolytebased Li-CO 2 batteries, the morphology of products in Li-CO 2 batteries using Bi-CoPc-GPE is film-like. Hence, this polymer-based Li-CO 2 battery shows superhigh discharge capacity, low overpotential, and even steadily runs for 120 cycles. This study may pave a new way to develop high-performance Li-CO 2 batteries.