Mesoporous LaFeO3 perovskite derived from MOF gel for all-solid-state symmetric supercapacitors

Sol-gel strategies have attracted enormous attention in synthesis of perovskite-type oxides due to their excellent chemical homogeneity and possibility in controlling the size, morphology, chemical properties and texture of particles. Nevertheless, their complicated, time-consuming process and weak control over porous structure impeded their potential use in preparation of energy storage materials. Herein, a simple and rapid strategy based on MOF gel (MIL-100-Fe) is developed for fabricating mesoporous perovskite-type materials. The MOF gel can be synthesized in controllable time duration without multi complexing agent, particular pH conditions and high temperature treatment. The synthesized perovskite LaFeO3 has mesoporous structure and the pore size is concentrated at 2 nm, which contribute to a specific capacitance of 241.3 F g−1 at 1 A g−1 with retention of 68% even at a high current density of 20 A g−1. Meanwhile, the all-solid-state symmetric supercapacitor shows a wide potential window of 1.8 V, and an outstanding energy density of 34 W h kg−1 at a power density of 900 W kg−1 with 92.2% capacitance retention after 5000 cycles, outperforming previously reported perovskite-type electrode materials and even comparable to MOF derived iron oxides. Thus, this study opens a new way to construct porous perovskite-type electrode materials for supercapacitors, which can combine the chemical homogeneity of sol-gel technology and the porous properties of MOF template together.