Single walled carbon nanotube functionalisation in printed supercapacitor devices and shielding effect of Tin(II) Oxide

Due to this generation facing the biggest energy crisis of its lifetime, the spotlight has been shone more than ever on the rapid development of green energy and its storage. Supercapacitors are an integral technology in this renewable energy storage due to their high-power density. For an increased energy density however, one must expand the voltage window of the device and utilise electrolytes that allow for the maximum storage capability of the material. Single walled carbon nanotubes (SWCNT) were identified at the turn of the century as an excellent material for use in supercapacitor electrodes, however, at anodic potentials in sulphate-based elec-trolytes, they undergo irreversible oxidation which damage their electrical properties and affects long term cycling stability. Herein we provide an effective strategy to expand the voltage window of SWCNTs to 1.4 V in sulphate-based electrolytes through the small addition of tin (II) oxide (SnO), with a capacity of 102 F g(-1) / 143 C g(-1) at a current density of 2 A g(-1). We study the effect of SnO and propose a pseudo-reversible oxidation reaction in which the SWCNTs are protected from oxidation through the formation of Sn3O4. Finally, an asymmetric device using MXene is assembled to illustrate the advantage of the expanded voltage window on energy density and cycling stability, with a capacity retention of 90% after 7,500 cycles at 10 A g(-1).

Automated summary

Due to the energy crisis faced by this generation, the development of green energy and its storage, particularly the use of supercapacitors, has become a focus of attention. Single walled carbon nanotubes (SWCNT) were identified as a promising material for supercapacitor electrodes, however, their electrical properties are damaged when exposed to anodic potentials in sulphate-based electrolytes. In this study, we propose a strategy to expand the voltage window of SWCNTs by adding tin (II) oxide (SnO), which protects the SWCNTs from oxidation and improves long-term cycling stability. We also demonstrate the advantage of the expanded voltage window in an asymmetric device using MXene, achieving a capacity retention of 90% after 7,500 cycles at 10 A g(-1).