Exploration of MnFeO₃/Multiwalled Carbon Nanotubes Composite as Potential Anode for Lithium Ion Batteries

MnFeO₃, investigated for its application in sensors, catalysis, and semiconductors, was explored for the first time as anode for lithium ion batteries in the form of MnFeO₃/multiwalled carbon nanotubes (MWCNT) composite. A scalable and highly reproducible sonochemical process was adopted to form the composite, wherein the interweaved MWCNT ensures better electronic conductivity and pinning of pristine MnFeO₃ particles with a conductive coating. MnFeO₃/MWCNT composite anode exhibits superior electrochemical properties than pristine MnFeO₃ anode in such a manner that a steady-state reversible capacity of 840 mAh g^–1 was obtained at 0.5 A g^–1 even after 50 cycles against an inferior capacity of 200 mAh g^–1 offered by MnFeO₃. Further, MnFeO₃/MWCNT composite anode shows excellent rate capability and reversibility by way of delivering appreciable capacity values of 2960 and 410 mAh g^–1 at 0.5 and 10 A g^–1, respectively. These results suggest that the currently synthesized MnFeO₃/MWCNT nanocomposite anode could be considered as a promising candidate for next-generation hybrid energy storage applications. The study is bestowed with the identification and demonstration of earth-abundant, environment-friendly, and low-cost metals, specifically, Mn- and Fe-based composite anodes for high capacity and high rate lithium ion battery applications, which is noteworthy

Shuttle Effect Quantification for Redox Ionic Liquid Electrolyte Correlated to the Coulombic Efficiency of Supercapacitors

International audienceThe use of redox active electrolyte is a good opportunity to increase the energy density of supercapacitors, the main limitation of this technology. The addition of redox molecules allows the storage of charge in the electrode and in the electrolyte. The key to keep the increase of charge is to avoid the shuttle effect of the redox molecule. Indeed, once the molecule is oxidized or reduced, it diffuses across the cell to react at the surface of the opposite electrode and the stored charge is lost. Is this shuttle effect however damageable for the device? This study proposes to answer this question by quantifying the shuttle effect and correlating it to the decrease of Coulombic efficiency of supercapacitors

Ex situ solid electrolyte interphase synthesis via radiolysis of Li-ion battery anode–electrolyte system for improved coulombic efficiency

International audienceThe radiolysis of a mixed solvent electrolyte–carbon anode material is investigated for the first time. The present work demonstrates the radiolytic growth of an SEI with a chemical composition similar to that formed during electrochemical cycling, as determined by XPS. The quantity of the SEI increases with increasing irradiation dose. Degradation products formed in the liquid and gas phase are also identified as matching those formed during electrochemical cycling. TEM results support the XPS results of increasing SEI content with increasing irradiation dose. Electrochemical characterization by galvanostatic cycling of test cells indicates that the radiolysis generated SEI greatly improves first cycle efficiency of the materials assembled in half cells, and impedance spectroscopy supports the result with an increase in resistivity observed for irradiated samples. This first study opens the door to the use of irradiation tools for the artificial generation of an SEI and for producing LIB anode materials with improved performance