Influence of binder and solvents on the electrochemical performance of screen-printed MXene electrodes.

The present study is concerned with the use of binders and solvents in fabricating MXene electrodes, which play a vital role in influencing supercapacitive performance. The electrodes were prepared by screen printing MXene on flexible stainless steel mesh (FSSM) substrate, which is a straightforward, efficient, and cost-effective approach. The influence of binder and solvent on the electrochemical performance was investigated by fabricating them with and without using a binder i.e. only organic solvents ethanol and n-methyl-2-pyrrolidone (NMP). The electrode with the binder is abbreviated as MX-B@FSSM and was prepared with the composition of acetylene black conducting material, polyvinylidene fluoride (PVDF) polymer binder, and MXene (MX) as active material. While electrodes without binder were prepared by a slurry of MXene using organic solvent ethanol and NMP and are abbreviated as MX-E@FSSM and MX-N@FSSM, respectively. The electrochemical performance of these MX-B@FSSM, MX-E@FSSM and MX-N@FSSM electrodes was examined by cyclic voltammetry, chronopotentiometry, and electrochemical impedance spectroscopy. The influence of the binder altered the electrochemical performance. The samples MX-B@FSSM, MX-E@FSSM, and MX-N@FSSM show the specific capacitance of 35.60, 490.80, and 339.6 F g-1, respectively at 2 mA cm-2current density. The MX-E@FSSM electrode exhibited marginally the best electrochemical performance. Furthermore, MnO2/MXene//MX-E asymmetric supercapacitor device exhibits 252 F g-1specific capacitance at 35.2 Wh kg-1energy density demonstrating a promising electrode for the supercapacitor.

Marigold micro-flower like NiCo2O4 grown on flexible stainless-steel mesh as an electrode for supercapacitors.

Nanostructured NiCo2O4 is a promising material for energy storage systems. Herein, we report the binder-free deposition of porous marigold micro-flower like NiCo2O4 (PNCO) on the flexible stainless-steel mesh (FSSM) as (PNCO@FSSM) electrode by simple chemical bath deposition. The SEM and EDS analysis revealed the marigold micro-flowers like morphology of NiCo2O4 and its elemental composition. The porous nature of the electrode is supported by the BET surface area (100.47 m2 g-1) and BJH pore size diameter (∼1.8 nm) analysis. This PNCO@FSSM electrode demonstrated a specific capacitance of 530 F g-1 at a high current density of 6 mA cm-2 and revealed 90.5% retention of specific capacitance after 3000 cycles. The asymmetric supercapacitor device NiCo2O4//rGO within a voltage window of 1.4 V delivered a maximum energy density of 41.66 W h kg-1 at a power density of 3000 W kg-1. The cyclic stability study of this device revealed 73.33% capacitance retention after 2000 cycles. These results indicate that the porous NiCo2O4 micro-flowers electrode is a promising functional material for the energy storage device.