Dataset Information

The Missing Piece: The Structure of the Ti₃C₂T_x MXene and Its Behavior as Negative Electrode in Sodium Ion Batteries.

ABSTRACT: The most common MXene composition Ti₃C₂T_x (T = F, O) shows outstanding stability as anode for sodium ion batteries (100% of capacity retention after 530 cycles with charge efficiency >99.7%). However, the reversibility of the intercalation/deintercalation process is strongly affected by the synthesis parameters determining, in turn, significant differences in the material structure. This study proposes a new approach to identify the crystal features influencing the performances, using a structural model built with a multitechnique approach that allows exploring the short-range order of the lamella. The model is then used to determine the long-range order by inserting defective elements into the structure. With this strategy it is possible to fit the MXene diffraction patterns, obtain the structural parameters including the stoichiometric composition of the terminations (neutron data), and quantify the structural disorder which can be used to discriminate the phases with the best electrochemical properties.

SUBMITTER: Ferrara C

PROVIDER: S-EPMC8517972 | biostudies-literature | 2021 Oct

REPOSITORIES: biostudies-literature

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Publications

The Missing Piece: The Structure of the Ti3C2Tx MXene and Its Behavior as Negative Electrode in Sodium Ion Batteries.

Ferrara Chiara C Gentile Antonio A Marchionna Stefano S Quinzeni Irene I Fracchia Martina M Ghigna Paolo P Pollastri Simone S Ritter Clemens C Vanacore Giovanni Maria GM Ruffo Riccardo R

Nano letters 20210923 19

The most common MXene composition Ti3C2Tx (T = F, O) shows outstanding stability as anode for sodium ion batteries (100% of capacity retention after 530 cycles with charge efficiency >99.7%). However, the reversibility of the intercalation/deintercalation process is strongly affected by the synthesis parameters determining, in turn, significant differences in the material structure. This study proposes a new approach to identify the crystal features influe ...[more]

PMID: 34553949

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Project description:The pursuit of new and better battery materials has given rise to numerous studies of the possibilities to use two-dimensional negative electrode materials, such as MXenes, in lithium-ion batteries. Nevertheless, both the origin of the capacity and the reasons for significant variations in the capacity seen for different MXene electrodes still remain unclear, even for the most studied MXene: Ti3C2 T x . Herein, freestanding Ti3C2 T x MXene films, composed only of Ti3C2 T x MXene flakes, are studied as additive-free negative lithium-ion battery electrodes, employing lithium metal half-cells and a combination of chronopotentiometry, cyclic voltammetry, X-ray photoelectron spectroscopy, hard X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy experiments. The aim of this study is to identify the redox reactions responsible for the observed reversible and irreversible capacities of Ti3C2 T x -based lithium-ion batteries as well as the reasons for the significant capacity variation seen in the literature. The results demonstrate that the reversible capacity mainly stems from redox reactions involving the T x -Ti-C titanium species situated on the surfaces of the MXene flakes, whereas the Ti-C titanium present in the core of the flakes remains electro-inactive. While a relatively low reversible capacity is obtained for electrodes composed of pristine Ti3C2 T x MXene flakes, significantly higher capacities are seen after having exposed the flakes to water and air prior to the manufacturing of the electrodes. This is ascribed to a change in the titanium oxidation state at the surfaces of the MXene flakes, resulting in increased concentrations of Ti(II), Ti(III), and Ti(IV) in the T x -Ti-C surface species. The significant irreversible capacity seen in the first cycles is mainly attributed to the presence of residual water in the Ti3C2 T x electrodes. As the capacities of Ti3C2 T x MXene negative electrodes depend on the concentration of Ti(II), Ti(III), and Ti(IV) in the T x -Ti-C surface species and the water content, different capacities can be expected when using different manufacturing, pretreatment, and drying procedures.

Dataset Information

The Missing Piece: The Structure of the Ti₃C₂T_x MXene and Its Behavior as Negative Electrode in Sodium Ion Batteries.

Publications

The Missing Piece: The Structure of the Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> MXene and Its Behavior as Negative Electrode in Sodium Ion Batteries.

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