It is a promising development strategy to use LiFePO4/Graphene (LFP/G) hybrid cathode lithium-ion batteries for electric vehicles (EVs), which can simultaneously solve issues of the lengthy charging time and the battery pack heat. To capture the characteristic regulation of the temperature distribution, the working voltage, the current density, and the total heat generation of the LFP/G battery, an electrochemical-thermal coupled model for the LFP/G battery was developed through a new modeling method in ANSYS FLUENT. The experimental results showed that tendencies of the temperature distribution and the working voltage were not only agreed well with simulations, but also accurately verified the hottest area of the LFP/G battery. Further studies used the comparative analyses of the maximal temperature between the LFP/G battery and the conventional LFP battery at different discharged C-rates, the results indicated that the LFP/G battery could restrain the increase of temperature through reduced contact resistances. Our results suggested that the electrochemical-thermal coupled model could be used for electric vehicles battery management system applications.