Boosting the performance of EDLC-type supercapacitors using glucose-derived carbon/MWCNT hybrid electrode material and different electrolytes

• A glucose-derived carbon/oxidized MWCNT hybrid obtained by a green process. • The hybrid had 1177 m 2 /g surface area with spherical particles in a CNT network. • Supercapacitor cells were assembled with H 2 SO 4 , H 3 PO 4 and PVA-H 3 PO 4 electrolytes. • The supercapacitor (SC) based on PVA-H 3 PO 4 had the best energy storage performance. • Energy and power densities improved by 83% and 46% over Supra50-based SC cell. In this work, a hybrid electrode material of glucose-derived carbon doped with oxidized multiwalled carbon nanotubes (CNT-O) was prepared and used as building block for the development of efficient sandwich-type supercapacitors (SCs). The influence of the type of electrolyte – H 2 SO 4 and H 3 PO 4 aqueous electrolytes and a safer solid-gel electrolyte of H 3 PO 4 -doped polyvinyl alcohol (PVA) – on the energy storage performance of the resulting SCs was unveiled. The hybrid material was fabricated through an eco-friendly process of hydrothermal carbonization of glucose with 2 wt% of CNT-O and subsequent physical activation. The hybrid exhibited high specific surface area (1177 m 2 g -1 ), analogous to that reported for activated carbons, and was composed of spherical particles embedded in a CNT network. The SC_AG@CNT-O based on PVA-H 3 PO 4 electrolyte exhibited the best energy storage performance, featuring an energy density of 41.57 μW h cm -2 at a power density of 66.82 mW cm -2 , which are 32.2% and 74.7% higher, respectively, than those of the SC based on reference activated carbon Supra50. Moreover, it exhibited notable cycling stability, maintaining 93% of its initial capacitance over 8000 consecutive i-V cycles. This work constitutes an advance in the fabrication of efficient SCs using sustainable electrode materials and safer solid-gel electrolytes, while highlighting the crucial role of electrode-electrolyte compatibility in boosting energy storage performance. Beyond energy storage, the as-prepared glucose-derived carbon/CNT-O hybrid electrode material combining high surface area and electrical conductivity opens promising prospects for other applications, such as electrocatalysis, electrochemical sensors, and environmental remediation.