Abstract: Formation process for a potassium-ion hybrid supercapacitor, the process comprising: a) supplying the potassium-ion hybrid supercapacitor comprising: a negative electrode comprising graphite, a positive electrode comprising activated carbon, an electrolyte comprising a potassium salt, b) charging the supercapacitor at constant current in a protocol of between Cx/50 and Cx/2, to a charge cutoff voltage of between 3.0 V and 3.3 V, c) holding the supercapacitor at the charge cutoff voltage until the leakage current is between Cx/2000 and Cx/500, d) discharging the supercapacitor at constant current in a protocol of between Cx/50 and Cx, to a discharge cutoff voltage of between 0 V and 2 V, where the process further comprises degassing the supercapacitor after one of steps b) to d).