In Li-ion technology, researchers and manufacturers use aluminium foil as current collector for the cathode electrode because it is able to form a passive layer on the surface and this prevents corrosion at high potentials. Aluminium corrosion can cause different problems: increase in the electrical resistance, passivation of the cathode active material, contamination of the electrolyte and the dissolved Al3+ ions can migrate and deposit to the counter anode. In this work by combining two concepts: i) super-concentrated electrolytes and ii) gel-like polymer electrolytes it was possible to develop an electrolyte that avoids the corrosion of the aluminium current collector without the need of using LiPF6 and EC. Additionally, the use of super concentrated electrolytes will increase the electrochemical stability compared to conventional organic-based electrolytes and the use of gel electrolytes will mitigate the problem of leaks associated with liquids, including superconcentrated electrolytes. In particular, we report on the physicochemical properties and the electrochemical behavior of gel-polymer electrolytes (GPE) composed of porous PVDF-HFP swollen by concentrated solutions of LiTFSI salt in DMC:FEC mixtures. The ionic conductivity of the different gels ranges between 10-5 and 10-4 S cm-1 at room temperature and the highest value (0.19 mS cm-1) was obtained for a superconcentrated gel electrolyte with the following composition DMC : FEC : LiTFSI = 2 : 1 : 1 (GPE-211). In most of the cases the t+ is quite high, in particular, GPE-031 and GPE-111 exhibited values of t+ of 0.40 and 0.56, respectively. The electrochemical stability window of this gel is improved with respect to a reference non-concentrated gel electrolyte, reaching 5V. Finally, Li / LFP and Li / NMC batteries were assembled with GPE-211, obtaining high capacity values of 147 mAh g-1 and 160 mAh g-1 at 0.1 mA cm-2, respectively, and good rate capability.

Development of gel-polymer electrolytes based on superconcentrated electrolytes for lithium metal batteries

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.