The heat generated by a lithium-ion battery (LIB) under fast charging conditions can influence the charging efficiency, lifetime, and security of the battery. Considering the Joule heat generation of the tabs during the fast charging process, the electrochemical-thermal coupling model of a ternary LIB is built. The voltage and temperature of the battery are calculated during the constant current charging processes of 1 C, 3 C, and 6 C. By comparing the calculation results with the experiment results, the effectiveness of the model is verified. The electrochemical performance and thermal performance of the battery under fast charging conditions are obtained and analyzed through the model. The effects of the structure parameters such as the positive electrode thickness, N/P ratio, separator thickness, tab size, and arrangement on the average volume heat generation rate and temperature rise of the battery are investigated at charging rates of 3 C and 6 C. The conclusions obtained can provide references for the battery structure design and battery thermal management system design oriented to fast charging applications.