Elastic electronic devices, such as supercapacitors (SCs), require sheets with excellent strength and conductance. In a study published in the journal EcoMat, inspired by the naturally existing sheet, an unsupported paper electrode was created using MXene (Ti3C2TX) “mesophilic-like” nanofilms, silver nanowires (Ag NWs), and wire. of “venous” cellulose for solid state supercapacitor applications.
Study: Scalable fabrication of MXene / Ag NWs / cellulose composite paper electrode as a foil for solid state supercapacitors. Image credit: NABODIN / Shutterstock.com
The appearance of MXenes
The scalable manufacture of nanoscale materials in unsupported electrode substances with excellent mechanical properties, superior electrical conductivity and exceptional electrolytic behavior is crucial for use in resilient electronic devices.
Due to their excellent conductance and pseudo-capacitive characteristics derived from surface-rich functional groups (-O, -F and -OH), MXenes have received a lot of focus as early transition metal carbonitrides. innovative two-dimensional.
As in the case of graphene, MXene nanofilms are susceptible to stacking and regrouping due to the significant attraction of van der Waals between neighboring MXene sheets, resulting in poor accessibility of electrolytic ions and a very low ionic diffusion kinetics.
Cellulose can improve the performance of MXenes
Numerous attempts have been made to address the limitations of MXenes. For example, combining them with polymers such as polyvinyl alcohol (PVA), PPy, and PANI may limit self-aggregation between MXene nanofilms.
Alternative carbon-based materials, such as carbon nanotubes (CNTs), graphene, and carbon nanofibers, could be used to improve the electrolytic properties of MXens. Cellulose has been shown to improve the final effectiveness of MXene-based products due to its availability and renewable.
For example, bacterial cellulose (BC) was easily mixed with MXene using the solution technique in a previous study. The resulting composite electrodes showed a high tensile strength of 70 MPa and a good specific area capacity of 111.5 mF cm-2.
Another study found that a self-supporting MXene / bacterial cellulose self-supporting sheet with a 3D porous architecture had a very high capacitive performance while having an exceptional mechanical strength of 43 MPa by melting frozen after vacuum filtration.
In addition, when cellulose nanofibrils were constructed with MXenes as functional additions, the material achieved a remarkable mechanical strength of 341 MPa as well as significant capacitive performance.
Despite significant advances, the use of cellulose as a functional addition does not allow the scalable manufacture of MXene-based electrodes. Achieving synergistic increases in many key aspects remains a challenge, including mechanical qualities, electrical conductance, and capacity.
The team used a quick and easy approach to vacuum-assisted filtering to create a super conductive composite paper inspired by the leaves of the plants. Microscale / nanoscale cellulose fibers served as a framework, while MXene nanofilms and silver nanowires (Ag NWs) served as functional complements.
Mechanically ground cellulose fiber had a higher aspect ratio and broader -OH groups. It could offer more hydrogen bonding points and stronger coupling, resulting in a hybrid paper with a larger specific area, a more densely ordered architecture, and significantly improved hardness.
Resembling the primary veins of a plant leaf, the intertwined cellulose fibers formed the central frame of the composite paper. MXene nanofilms, like mesophiles on a sheet, could be arranged on the surface of cellulose fibers and fill the space between fibers, facilitating electrolyte accessibility and storing the charges created by the entire structure.
Using a fast, scalable, vacuum-assisted filtering technique, microscale / nanoscale, MXene, and NW nanofilm cellulose fibers were evenly combined to produce a superconducting PMxAg hybrid paper with a leaf-like hierarchical architecture.
MXene nanofilms can be easily wound around cellulose filaments generating numerous hydrogen bonds. At the same time, silver nanowires can interpenetrate through MXene / cellulose structures, producing a bio-inspired leaf-like nanoscale architecture with an intertwined, highly conductive three-dimensional frame.
As a result, the electrical and mechanical properties of nanocomposite paper were greatly improved. Powerful interactions and three-dimensional structure ensured a fast-loading transport route and a fast loading / unloading operation, which significantly increased the exceptional electrolytic characteristics of the composite paper.
Consequently, the PMxAg nanocomposite paper electrode achieved a significant gravimetric capacity of 505 F g-1 at a scanning speed of 10 mV s-1, which is the largest of the MXene-based electrodes described so far. .
This technique for developing electrode materials proposed in this study was quite successful and economical to achieve optimal charge transfer and high performance SC, which indicates a huge promise for the next flexible electronic devices.
Tang, H., Chen, R., Huang, Q., Ge, W., Zhang, X., Yang, Y. and Wang, X. (2022). Scalable fabrication of MXene / Ag NWs / cellulose composite paper electrode as a foil for solid state supercapacitors. EcoMat. Available at: https://doi.org/10.1002/eom2.12247
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