Interfacial Stabilizing Effect of Lithium Borates and Pyrrolidinium Ionic Liquid in Gel Polymer Electrolytes for Lithium-Metal Batteries
Agnieszka Swiderska‐Mocek, Agnieszka Gabryelczyk
Abstract
High Resolution Image Download MS PowerPoint Slide The next generation of reversible batteries will be high-energy-density systems such as lithium-metal batteries. However, metallic lithium as the anode requires an electrolyte that prevents the formation of Li dendrites. The keynote of this work is a gel polymer electrolyte with a copolymer matrix made of PVdF(HFP), which is compatible with Li metal electrodes. The obtained gel polymer electrolytes contain lithium borate (LiBOB or LiDFOB), ionic liquid (EtMeImNTf 2 or MePrPyrNTf 2 ), and sulfolane (TMS). In this study, lithium borates are a central aspect affecting the performance of the electrolyte and electrodes. In turn, the ionic liquid in a mixture with sulfolane plays the double role of a lithium salt solvent and gel polymer membrane plasticizer, ensuring thermal stability and a higher proportion of amorphous areas in the polymer electrolyte. Furthermore, MePrPyrNTf 2 in the presence of lithium borates reduces the resistance ( R SEI ) of the layer formed at the electrolyte|Li electrode interface. Most gel electrolytes exhibit long-term stability at the GPE|Li interface. Membranes containing LiBOB or LiDFOB and pyrrolidinium ionic liquid also ensure compatibility with the olivine cathode in the cell, which delivers a capacity of 120 mAh g –1 (C/10) after 80 cycles and retains this value after an additional 105 cycles at C/2 and C/10.