Electrodes and transfer processes are the key to thermal electrochemical CO2 capture. The lifetime of electrodes and capture performance are significantly affected by the microscale (micro- and nanocrystalline) structural change and transfer mechanism. Experimental and time-consuming theoretical studies are expensive, and it is difficult to understand microscale structural changes and transfer mechanism due to a lack of relevant unified knowledge. Thus, a time-saving multiscale velocity unified theory was developed by synergizing the molecular motion and matter movement. The theory well predicts the microscale structural change in electrodes and quantifies the chemical reaction and heat and mass transfer under normal and superhigh/superlow operating conditions. A porous electrode and U-shaped multilayer electrode were designed, and the lifetime of electrodes increased by 30%. The U-shaped multilayer electrode self-repairs its microscale structure, and its mass transfer coefficient increased by 15%. The theory simplifies the computational fluid dynamics and molecular dynamics simulation.