Sonication-induced electrostatic assembly of an FeCO3@Ti3C2 nanocomposite for robust lithium storage

Abstract

Transition metal carbonates as represented by FeCO₃ have been widely evaluated as attractive anode alternatives for high-energy lithium ion batteries (LIBs), owing to their high practical lithium storage capacity approximately three times that of a conventional graphite anode. However, capacity-decay upon cycling and unsatisfactory rate performance have been the critical issues hindering their practical applications. We report here a structural reconstruction protocol, coupled with compositing with conductive MXene materials to address the above issues. Specifically, sonication-induced electrostatic assembly (SIEA) is exploited to convert a hybrid consisting of FeCO₃ microparticles and multilayered Ti₃C₂ stacks into reshaped FeCO₃ nanorods that are uniformly anchored at the surface of highly exfoliated Ti₃C₂ monolayers. Through the X-ray photoelectron spectroscopy (XPS) and zeta potential analysis, it was seen that the surface Fe²⁺ to Fe³⁺ oxidation plays a critical role in positively charging the particle surface of FeCO₃ nanorods, resulting in desired composite construction with the negatively charged Ti₃C₂ substrate. Within such a composite material, charge transfer to active FeCO₃ particles is effectively facilitated during lithiation/delithiation processes, which has been predicted by density functional theory (DFT) calculations and further verified by in situ electrochemical impedance spectroscopy (EIS) measurements. Concurrent implementation of nano-engineering and the MXene-support through the SIEA results in remarkably enhanced cycling stability and rate capability of the FeCO₃ anode material. This work offers an effective material engineering strategy to boost the lithium storage performance for transition metal carbonate anode materials.