Stabilizing Semi-Crystalline Phase in CsPbBr₃ Nanocrystals for Supercapacitor Application

Abstract

Halide perovskite-based energy storage devices have gained much attention due to their high electronic and ionic conductivity. However, poor performance and cyclic stability of hybrid halide perovskite supercapacitors have become the bottleneck for commercialization. Typical electrolytes used so far in halide perovskite-based supercapacitors are nonaqueous tetrabutylammonium tetrafluoroborate, or tetrabutylammonium perchlorate having large cations. We demonstrated that inorganic halide perovskite-based supercapacitors with Li-ion electrolytes are highly efficient with a specific energy density of ∼250 W h/kg. There are no structural changes in the two-dimensional tetragonal phase of the CsPb 2 Br 5 lattice. However, the orthorhombic phases of the three-dimensional CsPbBr 3 crystal structure disappear due to Li-ion intercalation/conversion. A quasi-reversibility is observed during the discharging cycles. We have also shown that introducing perovskite nanocrystals can stabilize the quasi-reversible orthorhombic to amorphous phase transition in CsPbBr 3 . This is mainly because of the nanocrystals' finite size (∼10 nm), where Li-ion intercalation results in a semicrystalline phase. Therefore, no such structural changes are observed in CsPbBr 3 nanocrystals during charging or discharging cycles in Li-ion electrolytes. We have further fabricated solid-state supercapacitors by introducing quasi-solid-state gel electrolytes between symmetric electrodes having an energy density over 4.58 μW h/cm 2 . These devices are stable over 5000 GCD (galvanostatic charge−discharge) cycles with more than 89% capacity retention.

Origin of the Substrate-Dependent Stability of a High-Performance Perovskite Supercapacitor for Flexible Electronics

“…We fabricated hybrid halide perovskite-based supercapacitors using a previously reported standard protocol. , We synthesized CsPbBr 3 nanocrystals directly from the solution to reduce the number of steps for electrode fabrication. The structural and morphological characterization of the directly synthesized perovskite powder is given in Figure S1.…”

“…Especially, lithium-ion-based electrolytes such as lithium bis(trifluoromethanesulfonyl)imide (LiTFSi) can improve the energy and power density of the halide perovskite supercapacitor significantly due to reversible lithiation. 35,36 In this paper, we have demonstrated that the flexible asymmetric supercapacitors (ASCs) fabricated on a graphite substrate using a quasi-solid-state gel electrolyte sandwiched between an activated carbon electrode and a porous perovskite electrode have high areal energy density (∼8.25 μWh/cm 2 ). We have further demonstrated the flexibility and stability of the supercapacitors on thick (200 μm) and thin (50 μm) SS substrates and flexible graphite (100 μm) substrates.…”

“…Apart from carbon nanomaterials, hybrid halide perovskites are a better alternative for flexible supercapacitor application due to their high electronic and ionic charge-transport properties. ,− Very recently, we demonstrated that a nonaqueous electrolyte such as tetrabutylammonium tetrafluoroborate or tetrabutylammonium perchlorate in a dichloromethane solvent or a lithium-ion-based electrolyte in ACN can be used as a stable electrolyte for supercapacitor application. Especially, lithium-ion-based electrolytes such as lithium bis­(trifluoromethanesulfonyl)­imide (LiTFSi) can improve the energy and power density of the halide perovskite supercapacitor significantly due to reversible lithiation. , …”

Lead-free halide perovskites for high-performance thin-film flexible supercapacitor applications

“…In recent studies with non-aqueous electrolytes, halide perovskite-based supercapacitors have emerged as promising materials for energy storage applications. 17–21 The majority of halide perovskite research has been focused on Pb-based materials, due to their excellent properties, and well-understood formation process. 22–24 However, lead (Pb) toxicity is still a source of contention.…”

Vacancy Ordered Lead Free Double Perovskite Based Flexible Supercapacitor for Sustainable Energy Applications

“…The charge storage is mostly due to the EDLC type. But for the advancement of hybrid supercapacitors, it is necessary to develop high-performance electrode materials. − Hybrid organic–inorganic halide perovskite materials are used in lot of application like solar cells, LEDs, photodetectors etc., due to their exceptional electrical and optical characteristics. − Recently, there are several reports on the use of halide perovskites in the field of supercapacitor application. − However, lead toxicity may prevent the commercialization of lead-halide-perovskite-based energy storage devices. By evaluating the environmental effects of lead (Pb) from perovskite-contaminated soil using plants, Li et al showed that Pb perovskites pollute 10 times more than other Pb contaminants .…”