A model of a lithium-ion battery suitable for energy storage application has been shown. The model was formulated in a general sense, but specifically for use in the SIMPLORER software. The method accounts for current rate- and temperature- dependence of the capacity and thermal dependence of the equilibrium potential. The modelling procedure, based on the experimental data, allows the model to have both good accuracy and the flexibility to represent other types of batteries. The mathematical description of the battery has been coded to a VHDL-AMS model in the SIMPLORER software.