The safety of lithium-ion battery provokes public concern with its wide application. Considering the electrical and thermal interplay between different parts or layers, a multilayer electro-thermal model is developed to investigate the performance in internal short-circuit (ISC) case before the trigger of thermal runaway. The battery internal short circuit is assumed to occur under natural convection condition and the initial temperature is 25 degrees C. In comparison, the simulation result agrees with the experimental data. It is found that the short-circuit performance is quite sensitive to the number of layer and short-circuit location. The current almost triples when the number of layer increases from 2 to 32. Moreover, weakening the electrical and thermal interplay between different layers can make the battery more secure in Al-anode ISC case. It is proposed that adding extra resistance on two adjacent metal tabs or changing tabs' position can improve the safety. Novelty Statement Electrical and thermal interplay between different layers is considered. Adding extra resistance between different unit layers protects battery from ISC. Weakening the electrical and thermal interplay between layers is recommended.