In a society increasingly concerned by its impact on the environment and the urgent issue of climate change, there is great demand for an energy storage device with higher energy density and power capability (especially for electric vehicles and power grid). The use of the high energy density lithium metal anode jointly with a solid polymer electrolyte could enable the development of large-scale battery applications. Yet, dendritic lithium formation leading to short circuit currently limits its practical applications. Therefore, understanding the fundamentals of dendrite nucleation and growth is necessary to design robust battery systems.

In this work, the nucleation and growth of lithium dendrite is studied in function of salt concentration in lithium-lithium symmetric cells in a rigorous manner. Complete electrochemical characterization of a solid block copolymer polystyrene-polyethylene oxide mixed with lithium salt (LiTFSI) will be presented, as well as the cell lifetime under galvanostatic cycling. We have discovered an unexpected relationship between cell lifetime and salt concentration. X-ray micro-tomography was used to underpin the relationship between salt concentration and dendrite nucleation and morphology.