**Bo-Min Kim 1, Hyo-Young Kim 2, Young-Wan Ju 2,3,\* and Jeeyoung Shin 1,4,\***


Received: 30 April 2020; Accepted: 8 June 2020; Published: 12 June 2020

**Abstract:** A supercapacitor is a potential energy system that will be a part of an efficient storage device of renewable energy, such as a small battery and a large energy storage system (ESS), etc. However, a lot of efforts have been devoted to improving stability. Generally, ABO3-type perovskite structure has been studied as an electrode and/or an oxide ion-conducting electrolyte for solid oxide fuel cells with stable structural stability at high temperatures. In this study, perovskite material (La0.8Sr0.2Mn0.5Co0.5O3-δ. LSMCO) was added as a component of the supercapacitor electrode for enhanced stability. According to electrochemical measurements, at 5 mV/s, the specific capacitance of the graphene-based electrode (G95) is 68 F/g, and the electrode mixed with perovskite (G70L25) is 55 F/g. Nonetheless, the standard deviation of the capacitance value of G70L25 is smaller than that of G95. Alongside this, the G70L25 electrode showed that specific capacitance decreased in the cycling test, but, for the G95 electrode, the specific capacitance after the 4990th cycle increased or decreased, resulting in unpredictable results. Therefore, perovskite added electrode (G70L25) shows higher stability compared to the graphene nanoplatelets electrode (G95) in both initial and cycling performance, albeit a lower specific capacitance.

**Keywords:** perovskite; supercapacitors; stability
