▎ 摘　　要

The present work is about synthesis of La doped (1-5 vol %) manganese oxide (MnO2) @ graphene oxide (GO) composite electrode. The thin films are obtained using a facile and binder free successive ionic layer adsorption and reaction (SILAR) method. The scanning electron microscopic image of 3%La-MnO2@GO composite thin film shows porous spongy-like nanoparticles. Nitrogen desorption analysis shows that mesoporous sheets of 3%La-MnO2@GO exhibits large surface area up to 149 m(2) g(-1). The highest electrochemical specific capacitance of 729 F g(-1) at the scan rate of 5 mV s(-1) is obtained for 3%La-MnO2@GO electrode. The 3%La-MnO2@GO thin film electrode exhibits 94% capacitive retention over 5000 CV cycles. The flexible symmetric solid state supercapacitor device of configuration SS/3%La-MnO2@GO/PVA-Na2SO4/3%La-MnO2@GO/SS operating in potential window 1.8 V shows maximum specific capacitance of 140 F g(-1) with energy density of 64 Wh kg(-1) at power density of 1 kW kg(-1) and capacitive retention of 90% after 5000 CV cycles at the scan rate of 100 mVs(-1). (C) 2020 Elsevier Ltd. All rights reserved.