High-performance and ultrafast symmetric supercapacitors based on cu(II)-doped SrSnO3 perovskites

Official URL: https://dx.doi.org/10.1021/acs.jpcc.5c03126

Herein, Cu(II)-doped SrSnO3perovskites (SrSn1–xCuxO3, namely SSO:Cux) were prepared by a modified Pechini method and applied as supercapacitors (SCs) for the first time. The effect of dopant concentration (x = 1, 2.5, and 5 mol %) was investigated to fine-tune the structural and electronic properties to design potential candidates as SCs. The SSO:Cux samples were characterized by conventional XRD and synchrotron XRD (S-XRD) combined with Rietveld refinements and spectroscopic analyses, such as Raman, FTIR, UV–vis, EPR, and XANES/NEXAFS. The electrochemical performance of the SSO:Cux samples was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic cycling with potential limitation (GCPL). It was evidenced that incorporating 2.5 mol % Cu(II) into the SrSnO3perovskite lattice (SrSn0.975Cu0.025O3, SSO:Cu2.5) led to a significant change in structural disorder and electronic properties, which play an essential role in creating a mixture of point defects such as reduced Sn3+and Cu+cations, and oxygen vacancies (VO). The SC device constructed with the SSO:Cu2.5 material showed a specific capacitance of 613 F g–1at a scan rate of 1 mV s–1, with a remarkable specific energy density and specific energy power of 25.42 W h kg–1and 32678.57 W kg–1, respectively, which are higher than those observed for any other available perovskite-based SCs. This performance was primarily attributed to the formation of mixed Sn4+/Sn3+and Cu2+/Cu+cations, which alter the structural and electronic properties of SrSnO3. Our findings indicate that an improved capability to store high energy and power may be achieved by fine-tuning the Cu(II) dopant concentration in the lattice and controlling the formation of undesired phases. This offers experimental guidance to design other Cu-doped perovskites as alternative materials for energy storage applications.