Lithium-ion batteries have enabled the portable electronic revolution of the past decade. However, before transportation and electricity generation can be revolutionized by electric vehicles and renewable energy technologies respectively, batteries with much higher energy densities must be developed. The next generation batteries currently being explored (e.g., lithium-sulfur and lithium-air) depend on lithium metal as the anode because lithium has a high gravimetric capacity. Unfortunately, lithium is quite reactive, and it continuously reacts with the electrolyte leading to poor cycle life. To control electrolyte degradation, we explored an unreactive nonpolar alkane as part of the electrolyte mixture to control the electrode-electrolyte interface. We observe that the nonpolar alkane modifies the lithium solvation structure within the electrolyte, changes the lithium deposition morphology, decreases the overpotentials required for deposition and stripping, and more importantly improves cycle life. Our work provides insight into the ion solvation structure and how reactions at the electrode-electrolyte interface can be tuned through careful understanding of ion solvation for lithium metal batteries.
Department of Chemical Engineering, Stanford University, USA