# Effect of MXene Nanosheet Sticking on Supercapacitor Device Performance
## 1 Introduction  
### Background  
MXenes, a family of two-dimensional transition metal carbides, nitrides, and carbonitrides, have attracted considerable interest in various fields due to their exceptional properties [1; 2; 3]. When it comes to their application in supercapacitors, MXenes offer several advantages. Their high surface area, mechanical strength, and electrical conductivity make them promising materials for energy storage devices like supercapacitors and batteries. Additionally, MXenes are capable of accommodating large numbers of ions on their high surface area, enhancing their charge storage capacity [4; 5; 6]. This feature is essential for supercapacitors, where the storage of electrical energy in the form of ions at the electrode-electrolyte interface is crucial. As a result, MXenes have the potential to offer high energy and power density in supercapacitor applications. The exceptional mechanical strength of MXenes ensures that the supercapacitor electrodes maintain their structural integrity during charging and discharging cycles. This property is important for achieving long-term stability and durability, as it prevents electrode degradation andmaintains the overall performance of the energy storage device over time. The excellent electrical conductivity of MXenes facilitates efficient charge transfer within the supercapacitor electrodes. This attribute enables rapid ion transport and electron mobility, leading to enhanced charge/discharge rates and overall electrochemical performance [7,8].  
Despite these advantages, one of the primary challenges with MXenes lies in their tendency to stack together, potentially hindering ion accessibility and electron transport within the supercapacitor electrode structure. This issue can impact the overall performance of supercapacitors utilizing MXenes. When MXene nanosheets stick together or aggregate, it hinders the accessibility of the active surface area which is essential for the adsorption of electrolyte ions. This reduced accessible surface area can lead to diminished charge storage capacity and lower overall energy density of the supercapacitor. Sticking of MXene nanosheets can result in elevated charge transfer resistance within the electrode material. This resistance impedes the movement of ions during the charge and discharge cycles, leading to slower kinetics and reduced power performance of the supercapacitor. Aggregated MXene nanosheets can hinder the diffusion of the electrolyte throughout the electrode material, leading to non-uniform electrolyte distribution. This can limit the overall utilization of the active material, impacting the overall capacitance and energy storage capability of the supercapacitor and batteries [9,10] due to localized overcharging or discharging, leading to reduced life cycle and potential safety risks within the storage element.  
Various approaches have been explored to mitigate these issues, such as intercalation technology and surface modifications with other nanomaterials. These strategies aim to improve the dispersion of MXene nanosheets and their adhesion to the supercapacitor electrodes, thereby enhancing the electrochemical performance and addressing the challenges associated with aggregation. Effectively tackling the obstacles related to nanosheet sticking and aggregation could pave the way for the widespread utilization of MXenes in supercapacitors, leading to the development of high-performance energy storage devices with improved efficiency and reliability.