Quantifying Capacitive and Diffusion-Controlled Charge Storage from 3D Bulk to 2D Layered Halide Perovskite-Based Porous Electrodes for Efficient Supercapacitor Applications

Abstract

Hybrid perovskites have been widely used in solar cells and light-emitting diode applications due to superior optoelectronic properties. However, ion migration in these materials causes photo- and thermal instability. On the other hand, mixed electronic–ionic conduction could be advantageous in electrochemical energy storage applications. We have fabricated porous electrodes from three-dimensional (3D) bulk and 2D layered perovskite single crystals and demonstrated that the ion migration could play a significant role in determining the overall performance of the electrochemical supercapacitor. The areal capacitance (∼58 mF cm–2), specific capacitance (∼36.82 F g–1), and energy density (∼9 W h kg–1) calculated at a current density of 0.6 mA cm–2 are higher in 3D perovskite-based supercapacitors, while the maximum power density (∼400 W kg–1) is significantly higher in 2D perovskite-based supercapacitors due to faster intercalation/deintercalation of the electrolyte ions into the porous electrode. We have also estimated the amount of diffusion-controlled charge storage to that of electric double-layer capacitance and surface redox reaction (pseudo-) capacitance from the power law relation in both the samples. The major difference is observed at a low-field regime, where ionic conductivity in 3D bulk perovskites is significantly higher than that in 2D-layered perovskites mainly due to strong electron–ion coupling. Therefore, in 3D perovskite-based supercapacitors, only 2% is diffusion-controlled charge storage compared to 40% in 2D samples at a low-field regime. With the increasing applied voltage, both capacitive and diffusion-controlled charge storage become comparable in both the samples. The 3D sample stability is ∼98%, while the 2D sample stability is almost 100% even after 1000 cycles of operation.

Hybrid Halide Perovskite‐Based Electrochemical Supercapacitors: Recent Progress and Perspective

“…One of the major discussions about perovskite-based devices is ion migration through perovskite active layer. It has been observed that ion migration in these devices is unpredictable due to various intrinsic as well as extrinsic parameters affecting ion kinetics, such as perovskite [21] Copyright 2021, American Chemical Society.…”

“…[ 18,19 ] In this direction, MHP materials are used in lithium‐ion batteries (LIBs), photorechargeable batteries (PRBs), and ESCs. [ 20–22 ] Typical stumbling blocks of rechargeable batteries are slow charging rate and low power density, while capacitors have low energy density than batteries. ESCs are the alternative energy storage sources with high power density and decent energy density as well as fast charging rate.…”

“…[14,52,53] This ion migration plays a very crucial role in the charge/energy storage mechanism. [21] Photoinduced ion migration in the perovskite active electrodes can modulate the total charge/ energy storage (Table 1).…”

“…MHP-based electrochemical cells with moderate energy density and power density demonstrate exceptional energy storage alternative sources. [21] The MHPs have many advantages over the state-of-art materials such as tunable ionic conductivity, high ionic as well as electronic conductivity, high defect tolerance factor, photoactive materials, and low-cost solution-processable fabrication methods. [24][25][26][27][28] These materials can be used as cathode/anode or both electrodes, and as electrolyte in the ESCs, as shown in the Figure 2.…”

“…The flow of charges and the storage mechanism in e) 2D and f ) 3D perovskite-based electrochemical cells. Reproduced with permission [21]. Copyright 2021, American Chemical Society.…”