Tin (Sn) anodes for sodium-ion batteries have recently been extensively investigated due to their high capacity (847 mAh/g), low average operating potential (~250 mV vs. Na/Na+), environmental benignity, and high abundance. Unfortunately, upon repeated charging/discharging, both the Sn electrode and Na metal suffers from large volume changes that rupture the solid electrolyte interphase (SEI) and initiate the onset of cell failure. To understand such complex and interrelated phenomena, we have designed a 3-electrode cell to track the evolution of the electrochemical signature of both the working and counter electrode. Additionally, we have compared the electrode morphology and electrode/electrolyte interface under different electrochemical conditions and probed these morphological/interfacial changes with cycling life performance to cultivate a holistic understanding of different types of failure mechanisms. In particular, we have discussed whether the primary reason for the shorter cycling life is the mesoscopic/macroscopic deformation of the Sn electrode caused by volume expansion/contraction or the continuous formation/breakdown of SEI. Furthermore, the effect of a localized electrochemical environment, which primarily depends on the choice of electrolytes (ether-based and carbonate-based), is also explored here.