Co-precipitation synthesis of pseudocapacitive λ-MnO2 for 2D MXene (Ti3C2Tx) based asymmetric flexible supercapacitor

Abstract

The rapid growth of wearable/portable electronics imposes a development of flexible, lightweight and highly efficient energy storage devices. In this work, we have synthesized A-MnO2 nanoplates through one step co-precipitation method and used for flexible asymmetric supercapacitor (SC). The structural, morphological and electrochemical properties of synthesized A-MnO2 were systematically investigated. The optical and electronic properties of A-MnO2 were studied using UV-vis spectroscopy and density functional theory (DFT) calculations. The pseudocapacitive A-MnO2 nanoplates-like electrode showed a maximum specific capacitance of 288.5 F g-1 at the scan rate of 5 mV s- 1. To check the practicability, symmetric (A-MnO2//A-MnO2) as well as asymmetric (A-MnO2//AC and A-MnO2//Ti3C2Tx MXene) SCs were fabricated and their performances were compared. The asymmetric A-MnO2//Ti3C2TxMXene SC demonstrated a maximum energy density of 15.5 Wh kg-1 at the power density 1100 W kg-1 along with 86.3 % of capacitive retention after 5000 cycles. Besides, to confirm the suit-ability of these electrodes for flexible energy storage, a flexible A-MnO2//Ti3C2Tx asymmetric SC was fabricated using PVA: Na2SO4 gel polymer electrolyte that operated in the potential window of 2 V and supplies high areal energy density of 39.9 & mu;Wh cm-2 at a power density of 8586 & mu;W cm-2. Therefore, the A-MnO2 prepared with a simple and scalable co-precipitation method may play a promising role in flexible energy storage.