Low-Dimensional Snse – Ti₃C₂ Mxene Composite As Binder-Free Anode for Energy Storage Applications

Two-dimensional (2D) materials exhibit unique structural and electronic properties such as reduced thickness, high conductivity, packing density and tuneable band gap. [1] These properties present compelling opportunities for their applications in sustainable battery technologies. [1] Sodium-ion batteries (SIBs) are attracting great interest as an alternative to lithium-ion batteries due to their material abundance, lower cost, and environmental sustainability. However, the quest for a high-performance anode for SIBs remains challenging owing to the severe volume expansion caused by the intercalation of the large Na-ion. Tin (II) selenide (SnSe), a layered 2D material, demonstrates very high theoretical capacity as an anode for sodium and lithium-ion batteries. Nevertheless, its instability primarily, attributed to the substantial pulverization of active materials during cycling, poses a challenge. [2] To address this, we investigated a novel 2D composite material comprising SnSe nanoparticles and MXene (Ti 3 C 2 T x ) nanosheets (Figure 1) to be used as an anode in batteries. Due to the exceptional conductivity and viscosity of MXene [3] , it can act as a conductive binder in this composite eliminating the need for traditional non-conductive binders like PVDF and CMC. This reduces the dead volume in the electrode and enhances its specific capacity. Additionally, the MXene layers with terminating fluorine functionals promote the growth of stable solid-electrolyte interfaces (SEI) improving the overall Coulombic efficiency of the battery. [4] Further optimization studies were done with VC and FEC electrolyte additives. Characterization techniques, including XPS, SEM, EDX, XRD, and AFM were performed on the composite nanomaterial to study its morphology, as well as compositional and structural changes upon processing. The electrode material showed a high initial discharge capacity of 700 mAh/g and 98% Coulombic efficiency for 100 cycles in lithium-ion batteries. This shows promise in overcoming the instability issues of SnSe, thereby improving the performance and longevity of SIBs for sustainable energy storage solutions. References [1] Jie Wang, et al., Nature Communications, 2021, Vol. 12 [2] Wei Wang, et al., Small, 2017, Vol.13 [3] Mohamed Alhabeb, et al., Chemistry of Materials, 2017 Vol. 29 Figure 1: SEM images of the cross-section of the SnSe-MXene composite slurry cast electrodes. a) shows the thickness of the slurry-casted electrode to be 11.6 microns and b) shows the SnSe nanoparticles between the MXene nanosheets. Figure 1