Effect of lithium doping on the electrochemical properties of Bi₂Sr₂Co₂O_y misfit-layered oxides for supercapacitor applications

The effect of lithium (Li) doping on Bi₂Sr₂Co₂O_y misfit layer oxides for supercapacitor applications is reported for the first time in this research paper. Four different compositions, which included Bi₂Li_0.1Sr_1.9Co₂O_y, Bi₂Li_0.1Sr₂Co₁.₉O_y, Bi₂Li_0.2Sr_1.8Co₂O_y, and Bi₂Li_0.2Sr₂Co_1.8O_y, were synthesized using a solution combustion method. The obtained powders were further calcined at 900 °C for 10 hours and subsequently characterized using field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) analysis and Raman spectroscopy to study the morphology, crystal structure, surface area, elemental identification, quantification, and bonding nature of Li-doped Bi₂Sr₂Co₂O_y. Cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) were performed for electrochemical characterization to study the effect of Li doping on the charge storage performance of Bi₂Sr₂Co₂O_y. Li doping enhanced the charge storage ability of Bi₂Sr₂Co₂O_y by 3 to 5 fold, and all compositions demonstrated a diffusion-based charge storage mechanism. The Bi₂Li_0.1Sr₂Co₁.₉O_y solid-state asymmetric device attained the highest specific capacity of 299.6 C/g at 5 mV/s and 241.5 C/g at 1 A/g with 53.7 Wh/kg energy density.