Strontium phosphide-polyaniline composites for high performance supercapattery devices

Abstract

Supercapattery, a hybrid energy storage device, gained remarkable attention due to its extraordinary energy storage performance. These devices constitute much better power and energy densities than supercapacitors and batteries. Here, we have investigated strontium phosphide and polyaniline (PANI) composites for supercapattery devices. The strontium phosphide was synthesized via facile sono-chemical method whereas the polyaniline was obtained through polymerization of aniline in acidic environment. Electrochemical performance of different mass ratios of strontium phosphide and polyaniline that are 75/25% and 50/50% were tested in three electrode assembly. Electrochemical characterization including galvanostatic charge discharge (GCD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) were performed to probe the electroactive nature of the composites. The initial characterization predicts the battery grade nature of synthesized composites which were confirmed through theoretical approach. The sample S3 indicates highest specific capacity of 192 Cg-1 in CV at a scan rate of 10 mV/s and 196 C/g in GCD at a current density of 0.4 A/g. In light of electrochemical performance, the 50/50% composite electrode was further investigated for supercapattery by sandwiching it with activated carbon electrode (capacitive electrode). The supercapattery (AC//S3) operates reliably at 0–1.7 V wider potential window in 1 M KOH environment and showing excellent specific capacity of 122.5 C/g at 0.6 A/g while demonstrating better rate capability of 37% at 3.0 A/g. Besides, this device expresses an outstanding performance in terms of energy and power density, 28.9 Wh/kg of maximum specific energy is achieved in line with 1020 W/kg of power density at 0.4 A/g. This device reveals an excellent power density of 5100 W/kg at the cost of 10.95 Wh/kg energy density. In last the device durability was examined by subjecting it to 2000 consecutive charge discharge cycles. Strontium phosphide/PANI composites would be novel electrode materials for state of the art supercapattery devices.