Catalyst-Free, Mechanically Robust, and Ion-Conductive Vitrimers for Self-Healing Ionogel Electrolytes

Abstract

Vitrimers have been widely employed in self-healing, recyclable, and shape-shifting materials. However, the application of catalyst-free vitrimers to create self-healable and mechanically robust gel polymer electrolytes (GPEs) remains a challenge, often limiting the potential of vitrimer-based materials. Herein, we utilized a catalyst-free dynamic covalent bond (silyl ether) as a linkage to prepare self-healable and mechanically robust GPEs, which are fully reprocessable. By incorporating polymeric ionic liquids into the dynamically cross-linked networks, both ion conductivity and mechanical properties can be flexibly tuned. The dynamic property of the network was demonstrated through frequency sweep rheology, which revealed a rubbery-like behavior at high frequencies and a liquidlike behavior at low frequencies. This dynamic feature enables self-healing and allows for reprocessing via embedding of such dynamic covalent networks into the GPEs. The GPEs containing 80 wt % of a bis(trifluoro­methansulfonamide) lithium/ionic liquid (LiTFSI/IL) mixture exhibited good ion conductivites of 0.13 mS/cm at 20 °C and 1.88 mS/cm at 80 °C. Furthermore, the elastic modulus of the GPEs could reach a value of 0.24 MPa and was able to persist through electrode-volume expansions during charging/discharging.The tunable dynamic properties, coupled with high ion conductivity and a high modulus, indicate promising applications for this type of dynamic bond in sustainable solid electrolytes.

Sustainable Benzoxazine-Sulfur Copolymer with Dynamic Linkages: Recycling, Reprocessing, Self-Healing, and Shape Recovery (R2S2)

“…11−14 This led to an advancement in polymer chemistry using the fundamentals of simple exchange reactions, allowing features of thermoplastics within thermosets. 15,16 In light of thermosets, polybenzoxazines (PBz) emerged as an upcoming alternative class to several traditional phenolic polymers with the pioneering work by Ning and Ishida. 17 bearing six-membered heterocyclic ring fused with an aromatic ring and is typically prepared via a simple Mannich-like condensation reaction of phenol, primary amine, and aldehyde.…”

“…Even though recycling or repurposing polymers appeared as an appealing strategy, repetitive processing imbues deterioration in properties due to uncontrollable structural alterations and heterogeneities developed upon reuse. Recently, tailoring of dynamic covalent bonds with triggered reversibility at the molecular level has shown great promise to overcome these challenges. − The pioneering work in 2010–2011 by Kloxin et al and Liebler et al discussed the introduction of dissociative and associative covalent adaptable networks (CANs) in thermosets; the latter are classified as “vitrimers” and have significantly progressed over the years. − This led to an advancement in polymer chemistry using the fundamentals of simple exchange reactions, allowing features of thermoplastics within thermosets. , …”