This paper proposes a temperature-dependent degradation modeling approach for lithium-ion batteries using PyBaMM. A DFN-based model is extended by integrating sub-models for solid electrolyte interphase (SEI) growth, lithium plating, and loss of active material to more accurately represent the underlying degradation mechanisms. Charge–discharge simulations are conducted under various temperature conditions to identify the dominant degradation mechanisms at each temperature. Simulation results show that lithium plating and mechanical stress primarily contribute to degradation at low temperatures, whereas SEI growth becomes more significant at high temperatures.