# Effect of MXene Nanosheet Sticking on Supercapacitor Device Performance
## 4 Approaches for Preventing Sticking of MXenes
### Electrode Processing Optimization  
Apart from the composition of the MXene itself, the interactions of colloidal particles are influenced by their surrounding medium. Instead of solely specifying the solvent used, it is essential to consider the ionic strength, determined by salt concentration, as it impacts the Debye screening length, which is directly linked to the strength of percolating networks, influencing rheology. Additionally, the solvent's acidity (or pH in the case of water) plays a role in determining the ratio of protonated and deprotonated alcohol termination groups (-OH/-O-). This parameter affects the thermodynamic stability of termination group mixtures and influences the preference for parallel or perpendicular flake stacking [80]. The hydrophilic nature of Ti\({}_{3}\)C\({}_{2}\)T\({}_{\rm x}\) layers due to the presence of polar and terminal groups enables easy dispersion in various polar solvents, forming dilute colloids (Figure 19). At higher concentrations, the non-uniform distribution of charges on the 2D monolayers (positively charged at the edges and negatively charged on the basal plane) leads to clay-like swelling as the flakes assemble. In the case of Ti\({}_{3}\)C\({}_{2}\)T\({}_{\rm x}\) MXene, it has been determined that the optimal parameters of the selected solvent involve surface tensions ranging from 35 to 42 mN/m and a ratio of polar/dispersive components between 0.61 and 0.87. For example, solvents such as propylene carbonate, NMP, DMF, and DMSO serve as effective carrier solvents for this  
Figure 18: SEM images of polystyrene spheres of different diameters (**a**,**d**,**g**), PS incorporated in MXenes (**b**,**e**,**h**) and introducing carbon nanotubes into the composite (**c**,**f**,**i**) [77]. Reprinted from [PERSON] et al., Nano Micro Small, copyright (2022), [PERSON] Wiley and Sons. MXene type. It has also been demonstrated that the synthesis route and the types of surface groups of MXene significantly influence its dispersibility, thereby enabling the use of various solvents for ink formulation by modifying the MXene's surface chemistry. This approach even offers the possibility of converting hydrophilic MXene to hydrophobic and dispersing it in organic solvents. Since MXenes are primarily synthesized using solution-based methods, it is preferable to employ liquid-phase fabrication techniques such as printing or coating for further processing, including device fabrication. These techniques involve processing stable MXene dispersions into continuous films with good adhesion to the target substrate. Such a dispersion is typically referred to as an ink and typically contains additives (e.g., binders, surfactants) to improve processability and film formation behavior [82]. In most cases, these additives degrade the electronic properties of the films/structures and should be removed at the end of the fabrication process. As the treatment time increases, it is understood that continual removal of Al leads to increased delamination, causing the stacked sheets to thin. HF is used to exfoliate the MAX phase and produce Ti\({}_{3}\)C\({}_{2}\) MXene nanosheets. Developing MoS\({}_{2}\)/MO\({}_{2}\)Ti\({}_{2}\)T\({}_{x}\) heterostructures results in an open architecture formed of 2D sheets, compared to pure MO\({}_{2}\)Ti\({}_{2}\)T\({}_{x}\), created by filtering of a colloidal solution and involving non-stacked 2D sheets. Figure 20 demonstrates that the interlayer distance of this compound was about 9.4 angstroms, which is close to that of bulk MoS\({}_{2}\) (~6.2 angstroms). The interaction of two layers of MoS\({}_{2}\) with layers of MO\({}_{2}\)Ti\({}_{2}\)T\({}_{x}\) leads to the creation of MoS\({}_{2}\)-on-MXene heterostructures. Examination of the transmission electron micrograph of MoS\({}_{2}\)/MO\({}_{2}\)Ti\({}_{2}\)T\({}_{x}\) reveals a larger quantity of MoS\({}_{2}\) layers, which hinders the stacking of MXene sheets. MoS\({}_{2}\) is usually prepared by mechanical or electrochemical exfoliation, hydrothermal, or microwave synthesis.