Cross-Linked Gel Electrolytes with Self-Healing Functionalities for Smart Lithium Batteries.

Abstract

Next-generation Li-ion batteries must guarantee improved durability, quality, reliability, and safety to satisfy the stringent technical requirements of crucial sectors such as e-mobility. One breakthrough strategy to overcome the degradation phenomena affecting the battery performance is the development of advanced materials integrating smart functionalities, such as self-healing units. Herein, we propose a gel electrolyte based on a uniform and highly cross-linked network, hosting a high amount of liquid electrolyte, with multiple advantages: (i) autonomous, fast self-healing, and a promising PF5-scavenging role; (ii) solid-like mechanical stability despite the large fraction of entrapped liquid; and (iii) good Li+ transport. It is shown that such a gel electrolyte has very good conductivity (>1.0 mS cm-1 at 40 °C) with low activation energy (0.25 eV) for the ion transport. The transport properties are easily restored in the case of physical damages, thanks to the outstanding capability of the polymer to intrinsically repair severe cracks or fractures. The good elastic modulus of the cross-linked network, combined with the high fraction of anions immobilized within the polymer backbone, guarantees stable Li electrodeposition, disfavoring the formation of mossy dendrites with the Li metal anode. We demonstrate the electrolyte performance in a full-cell configuration with a LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode, obtaining good cycling performance and stability.