Sensitivity of power of lithium-ion batteries to temperature: A case study using cylindrical- and pouch-type cells

Power measurement has become as important as capacity to ensure stable operating conditions for batteries at different temperatures, states of charge (SOCs), and states of health (SOHs). Unlike capacity, the power of a lithium-ion battery (LIB) is quite sensitive to temperature. However, there have been few systematic works on the measurement of power at different temperatures with various LIB types. Herein, the power of two types of LIB (cylindrical and pouch), which are normally used in traction applications, are measured at different temperatures (15, 25 and 35 °C) using the hybrid pulse power characterization (HPPC) method. When LIB reaches to each thermal equilibrium, the battery is discharged and charged for 10 s at a specific SOC by applying constant current. And then, power value could be obtained through calculating some simple equations. In normal operating conditions, capacity change little (~0.47% per °C) regardless of temperature change, but power increase by about 3% per °C. Considering that each cell type has a totally different cell configuration, the similarity of this trend between LIB types is quite noticeable. Consequently, when measuring the power of LIB, the temperature must be controlled precisely, or at least calibrated if temperature differences are observed.