Li-ion batteries have revolutionized a wide range of industries, from consumer electronics to vehicles. Their relatively high power and energy density and exceptional Coulombic efficiency are particularly advantageous for portable applications. Significant efforts have gone into studying the impact of thermal conditions on the electrochemical characteristics of Li-ion batteries because, in part, of the wide range of temperatures these devices are operated in. Recently, we have shown that thermo-electrochemical coupling in Li-ion batteries is of critical importance. In this talk, we will highlight some of our recent work that measures the local thermal conditions within the cell using embedded instrumentation and illustrates how significant thermal variations within the cell, specifically thermal gradients, are on electrochemical behavior. Moreover, we will discuss our efforts to pinpoint the underlying mechanisms that give rise to these effects.Acknowledgments:The authors thank Dr. Michele Anderson (Office of Naval Research, grant N00014-22-1-2411) for financial support of this work.