Boosting the performance of rGO aerogel-based symmetric supercapacitor using nitrogen doping and a redox-active electrolyte

• Easy and sustainable hydrothermal reduced graphene oxide aerogel (N-rGO aero) was developed. • Simultaneous N-doping and redox-active electrolyte yields the best electrochemical performance of the device. • Various hydroquinone additive concentrations in acidic electrolytes impact the supercapacitor performance. • An aqueous symmetric supercapacitor with 1 M H 2 SO 4 + 0.2 M HQ delivered high energy density (29.2 Wh kg −1 ). • The device exhibits outstanding cycling stability over 12000 cycles for a device with a redox electrolyte. This study presents the unique performance enhancement of reduced graphene oxide (rGO) aerogel–based symmetric supercapacitors achieved using simultaneous nitrogen doping and introduction of redox-active compound (hydroquinone – HQ) into the electrolyte. For the first time, a systematical investigation was performed to understand how the combined approach is beneficial for electrochemical performance of the graphene-based, symmetric, aqueous supercapacitors. The combined approach considerably improves the energy density of the modified N-rGO aero device exhibiting a maximum energy density of 29.2 Wh kg −1 at 0.076 kW kg −1 . Supercapacitor achieved over 27 % higher energy density compared to rGO aero in 1 M H 2 SO 4 + 0.2 M HQ and 52 % higher energy density compared to N-rGO aero in 1 M H 2 SO 4 . The potential window of rGO aero-based symmetric supercapacitor is effectively expanded to 1.4 V using the combined approach, ensuring its compatibility in various applications. Long-term stability tests reveal that the assembled devices exhibit remarkable capacitance retention nearly 100 % after 12000 charge–discharge cycles. These findings demonstrate that the developed N-rGO aerogel–based supercapacitors are promising candidates for high-performance electrochemical energy storage applications, including portable and hybrid energy systems.