The growing demand for high-energy-density lithium-ion batteries has intensified the search for advanced anode materials with exceptional capacity, stability, and fast kinetics. Among emerging candidates, MAX phases—layered ternary transition metal carbides and nitrides—offer a unique combination of metallic conductivity, mechanical strength, and tunable surface chemistry. However, their practical application remains limited by low specific capacity due to the difficulty in achieving fully exfoliated, ultrathin nanostructures that enable efficient ion transport and maximize electrochemical accessibility.
In this study, we present a highly effective strategy to overcome these limitations through synergistic Li⁺ intercalation and DMSO-assisted delamination of Ti₂SnC, a Sn-containing MAX phase. The process begins with the synthesis of bulk Ti₂SnC via self-propagating high-temperature synthesis (SHS), followed by sequential acid washing using hydrochloric acid and aqua regia to remove free Sn and TiC impurities. This pretreatment not only purifies the material but also introduces surface defects such as microholes and intergranular gullies, which act as preferential channels for solvent infiltration.
The purified powder is then dispersed in dimethyl sulfoxide (DMSO) and subjected to 24 hours of ultrasonic treatment under argon atmosphere. DMSO’s strong polarity and large dipole moment facilitate deep intercalation between the Ti₂C and Sn layers, weakening the MX–A bonding and enabling efficient delamination into two-dimensional (2D) nanosheets. Centrifugation and filtration yield ultrathin Ti₂SnC flakes with a thickness reduced from hundreds of nanometers to approximately 4.5 nm after 1000 charge-discharge cycles, as confirmed by atomic force microscopy (AFM) and transmission electron microscopy (TEM). X-ray diffraction (XRD) analysis shows peak broadening post-exfoliation, indicating successful reduction in layer thickness without phase degradation or amorphization.
Electrochemical evaluation reveals outstanding performance. At a current density of 50 mA g⁻¹, the exfoliated Ti₂SnC nanosheets deliver a reversible specific capacity of 735 mA h g⁻¹ after 1000 cycles—far exceeding the capacities reported for other MAX phases such as Ti₂SC (389 mA h g⁻¹), Ti₃SiC₂, and Nb₂SnC. Even at 400 mA g⁻¹, the capacity stabilizes at 430 mA h g⁻¹, demonstrating excellent rate capability. Notably, the capacity increases progressively over cycling, suggesting that continuous Li⁺ insertion induces further exfoliation, exposing more active sites for electrochemical reactions.
Cyclic voltammetry (CV) shows well-defined redox peaks corresponding to SEI formation, Li⁺ intercalation into Ti₂SnC, alloying of Sn with Li to form LiₓSn, and reversible de-alloying. The widening of these peaks after prolonged cycling indicates enhanced reaction kinetics. Electrochemical impedance spectroscopy (EIS) confirms a significant decrease in charge transfer resistance, consistent with improved ion diffusion pathways in thinner nanosheets.283173-50-2 Formula
XPS and HRTEM analyses confirm the preservation of the original crystal structure, while surface oxidation products like SnO₂ and TiO₂ are present in minimal quantities.148757-94-2 InChIKey These contribute negligibly to capacity, confirming that the primary mechanism is the Sn–Li alloying reaction.PMID:31082102 The theoretical capacity based on complete conversion to Li₄.₄Sn is ~521 mA h g⁻¹, yet the experimental value exceeds this, likely due to capacitive contributions from surface functional groups and increased electroactive surface area.
Crucially, the use of DMSO instead of ethanol enables superior exfoliation efficiency, yielding thinner, more transparent nanosheets with fewer layers. This enhances Li⁺ diffusion and reduces internal resistance. Furthermore, the coulombic efficiency stabilizes near 100% after initial cycles, indicating stable SEI formation and minimal irreversible side reactions.
In conclusion, this work demonstrates that synergistic intercalation and DMSO-assisted delamination can unlock the full electrochemical potential of Ti₂SnC MAX phases. The resulting 2D nanosheets exhibit record-breaking capacity, dynamic structural evolution during cycling, and excellent long-term stability. These findings provide a new design principle for high-performance anodes based on MAX phases and underscore the importance of solvent selection in nanostructure engineering for energy storage applications.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com
