2D Van der Waal heterostructured bitransition mixed chalcogenide engineered NixCo1-xSSe-based supercapacitors with extended calendar life

This research investigates the supercapacitor potential of 2D Van der Waals structures by introducing mixed chalcogenides to address inherent layer stacking constraints. The specific capacitance is improved by selenium and sulfur, and electrochemical properties are further enhanced by cobalt through a simple one-step synthesis. The Ni x Co 1-x SSe coin cell shows a capacitance of 464 Fg −1 at 2 Ag −1 . At 5 Ag −1 the symmetric coin cell 1 exhibits 99 % retention over 30,000 cycles and at 10 Ag −1 asymmetric coin cell 2 exhibits 87.54 % retention over 60,000 cycles. Cell 1 shows good stability and shelf life after two years, with a capacitance retention of 93 % and a 24 % decline from the original fabrication after 1,00,000 cycles. The potential of binary metal mixed chalcogenides to advance supercapacitor technology is made evident by this work. • Ni 0.6 Co 0.4 SSe nanosheets are prepared to facilitate better charge storage. • The Ni 0.6 Co 0.4 SSe coin cell supercapacitor offers 464 Fg −1 at 2 Ag −1 . • The Ni 0.6 Co 0.4 SSe coin cell showed 99 % retention at 5 Ag −1 for 30,000 cycles. • The coin cell has a 24 % decline in capacitance after 2 years of shelf life.