Sonication-induced electrostatic assembly of an FeCO 3 @Ti 3 C 2 nanocomposite for robust lithium storage

Transition metal carbonates as represented by FeCO 3 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 FeCO 3 microparticles and multilayered Ti 3 C 2 stacks into reshaped FeCO 3 nanorods that are uniformly anchored at the surface of highly exfoliated Ti 3 C 2 monolayers. Through the X-ray photoelectron spectroscopy (XPS) and zeta potential analysis, it was seen that the surface Fe 2+ to Fe 3+ oxidation plays a critical role in positively charging the particle surface of FeCO 3 nanorods, resulting in desired composite construction with the negatively charged Ti 3 C 2 substrate. Within such a composite material, charge transfer to active FeCO 3 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 FeCO 3 anode material. This work offers an effective material engineering strategy to boost the lithium storage performance for transition metal carbonate anode materials.