Effect of in situ annealing on pulsed laser ablated mixed metal oxide (BixMyOz; M=Mn, Mo) thin film electrodes for flexible hybrid supercapacitor devices

Abstract

Recently, solid-state thin film hybrid supercapacitor devices (TFHSCs) have had greater attention due to their miniaturized device assembly, portability, and superior cycling stability. Herein, for the first time, we assembled BiMn_xO_y ǁ PVA-KOH ǁ Bi₂MoO₆ thin-film solid-state supercapacitor devices by pulsed laser deposition (PLD) technique. In the present work, Bi₂MoO₆ and BiMn_xO_y thin film electrodes are fabricated at in-situ annealed conditions and their structural, morphological, and electrochemical performances are examined distinctly. We assembled a thin-film based BiMn_xO_y ǁ PVA-KOH ǁ BiMn_xO_y symmetric supercapacitor device (SSD) and that device delivers a functioning voltage of 1.4 V. Also, the device exhibits an extremely specific areal capacitance of 41 mF cm⁻² at 1 mA cm⁻². Similarly, a thin film-based Bi₂MoO₆ ǁ PVA-KOH ǁ Bi₂MoO₆ SSD attained a maximum specific areal capacitance of 13.33 mF cm⁻². Further, the assembled BiMn_xO_y ǁ PVA-KOH ǁ Bi₂MoO₆ TFHSC device delivers a voltage of 1.6 V and the TFHSC device exhibited a maximum specific areal capacitance of 52 mF cm⁻² at a fixed current density of about 2 mA cm⁻². The BiMn_xO_y ǁ PVA-KOH ǁ Bi₂MoO₆ TFHSC device shows outstanding stability performances such as 99 % of capacitance retention as well as 93 % of coulombic efficiency after 25,000 charge/discharge cycles. Additionally, the TFHSC device delivers a maximum areal energy density and power density of 18.5 μWh.cm⁻², and 978.7 μW cm⁻², respectively.