One-dimensional polythiophene/multi-walled carbon nanotube composite cathodes for rechargeable magnesium battery: Evidence of improved stability and electrochemically induced rearrangement in electrode morphology

• Published in: Electrochimica acta 2022-02, Vol.404, p.139707, Article 139707
• Main Authors: Raju, Vadthya, Rani, J Vatsala, Basak, Pratyay
• Format: Article
• Language: English
• Subjects: Cathodes; Charge transport; Chemical synthesis; Composite materials; Discharge; Electrochemical analysis; Electrode materials; Electrodes; Emission analysis; Field emission; Fourier transforms; Lithium; Magnesium; Morphology; Multi wall carbon nanotubes; MWCNT; Photoelectrons; Polymer composite; Polymer matrix composites; Polymers; Polythiophene; Rechargeable batteries; Rechargeable magnesium batteries; Stability
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2021.139707

•Single-phase polythiophene-MWCNT composite achieved through in-situ chemical oxidative synthetic procedure.•PTh/MWCNT application as cathode for rechargeable Mg battery demonstrates improved electrochemical activity over pristine PTh.•A high discharge capacity of ∼157 mAh.g−1 achieved at an applied current density of 60 mA.g−1, sustained for >100 cycles.•Post electrochemical analysis defines the multi-polaron state associated with polythiophene composite electrode.•Electrochemically induced rearrangement/reorganization in electrode morphology imparts improved stability. This paper showcases polythiophene/multi-walled carbon nanotube (PTh/MWCNT), synthesized via chemical in-situ oxidative method as an active cathode material for rechargeable magnesium (Mg) battery. Successful formation of the composite material is confirmed by Fourier transform-Infra Red and X-ray diffraction analysis. Morphological evaluations of the cathode materials employing field emission scanning- and transmission- electron microscopy (FESEM and TEM) reveal the composites’ one-dimensional, homogeneous phase formation. The feasibility of PTh/MWCNT composite as a prospective positive electrode for rechargeable magnesium battery is assessed using cyclic voltammetry and galvanostatic charge-discharge. Comprehensive electrochemical studies demonstrate a significantly enhanced performance of the optimized PTh/MWCNT cathode composition. A considerably high specific capacity of ∼157 mAh.g−1 coupled with appreciable coulombic efficiency (∼70%) and excellent reversibility (>100 cycles), at high current density, indicates great promise. Analysis by X-ray photoelectron spectroscopy confirms the existence of multi-polaron state of the polymer/composites providing crucial clues towards proposing a plausible mechanism of charge transport and storage. Affirmation of improved stability and electrochemically induced rearrangement in electrode morphology is clearly evidenced from the FESEM studies post charge-discharge cycles. These encouraging findings suggest PTh/MWCNT composite electrodes possess the desirable physical and electrochemical properties, to be considered as a potential polymer electrode for rechargeable Mg-battery. Schematic representation of red-ox reactions occurring in the Mg-PTh/MWCNT cell consisting 1.0M Mg(ClO4)2/acetonitrile electrolyte and representative cyclic voltammetry of the cell over multiple number of cycles [Display omitted] .