Synthesis of porous electrode from CH3NH3PbBr3 single crystal for efficient supercapacitor application: Role of morphology on the charge storage and stability

Abstract

Metal halide perovskites (MHPs) are the most exciting class of next generation energy storage materials owing to their high ionic as well as electronic conductivity. There has been tremendous progress in perovskite solar cells as well as perovskite light emitting diodes in last decade, however the use of halide perovskites is limited in energy storage application. Moreover, the device performance of MHP based supercapacitors is still inferior due to the lack of fundamental understanding of charge storage in perovskite supercapacitor. Here, we have fabricated methylammonium lead tri-bromide perovskite-based electrode by spin-coating as well as from the single crystal for electrolyte-based supercapacitors and demonstrated that the device performance strongly dependent on the electrode morphology. Our experimental results show that the modified electrode from the MHP single crystal has 500-time higher volumetric capacitance (∼ 429.1 F cm−3 @ 5 mV s−1) compared to the spin-coated thin-film based capacitors (∼ 0.8 F cm−3 @ 5 mV s−1) having same electrolyte and device structure. The modified electrode exhibits much higher ionic diffusion coefficient of 5.61 × 10−13 m2 s−1, and a very low charge transfer resistance (CTR) of ∼ 62.5 Ω cm−2 compared to thin film-based electrodes (Dion = 1.41 × 10−16 m2 s−1, CTR ∼ 4.4 kΩ cm−2) due to highly porous isotropic structure with high degree of micro-strain. Moreover, MHPs based supercapacitor exhibits a very quick energy deliver response time of 5 – 13 ms. We have got energy density ∼12.75 W h kg–1 at a power density of ∼225 W kg–1 which shows significant improvement in metal halide perovskite-based energy storage devices. We have found that the major contribution in powder electrode-based capacitor is diffusion limited capacitance while thin-film based devices show mainly electric double layer capacitance. Our modified powder electrode-based supercapacitors show significant improvement in terms of cyclic stability over 97% as well as coulombic efficiency over 91% after 1500 cycles of operation.