Aprotic Li-CO2 batteries offer a sustainable strategy for large-scale CO2 fixation and meanwhile providing electricity with high specific energy densities. However, the limited practical capacity hinders the application of this technology. To achieve a high-capacity Li-CO2 battery, parameter sensitivity analysis based on a developed model is conducted in this work to identify the limiting factors. It is found that the initial porosity of the cathode is the most determining factor to the specific capacity. To this end, various cathode structures including hierarchical, tapered, parabolic, trapezoid, and frustum conical pore distribution modes are designed and evaluated. Among these designs, the frustum conical porous cathode compared to homogeneous one can lead to the largest capacity improvement of over 60%, demonstrating the feasibility of improving the capacity through structure design. Besides, the present sensitivity analysis system is evaluated at high current densities, and the experimental approaches for fabricating the designed cathodes are proposed and detailly elaborated. This work highlights the effective cathode structure design for high-performance aprotic Li-CO2 batteries.