Electrochemical synthesis and performance of polyaniline/MnO2/graphene oxide composites cathode for seawater battery

Comparing the specific energy of the PANI/MnO2/GO(PMGO) electrode and the PANI/GO(PGO) electrode (d), it can be concluded that the PMGO electrode shows better electrochemical performance. The nanowire and 3D network morphology of the PMGO electrodes, as well as containing a certain amount of MnO2, are beneficial to reduce the polarization of PMGO electrode and promote electrode reaction. [Display omitted] •PANI/MnO2/GO(PMGO) composite as the cathode of Mg seawater battery is synthesized on the surface of oxidized graphite paper by an in-situ environment- friendly electrochemical oxidation method.•The nanowire and 3D network morphology of the PMGO electrodes, as well as containing a certain amount of MnO2, are beneficial to reduce the polarization and promote the electrode reaction.•The assembled PMGO/Mg seawater battery has high working voltage and high specific energy than those of pressed PM/Mg or AgCl/Mg battery. Conductive polyaniline (PANI) has been used as electrode materials in battery and supercapacitor for decades. However, there are few publications on PANI electrodes for seawater batteries because of its worse machinability and conductivity. This study demonstrates a durable and ultra-stable conductive PANI/MnO2/graphene oxide (PMGO) composite cathode synthesized by an in-situ electrochemical method on the graphite paper with excellent machinability and conductivity. The component, structures, and properties of the materials are characterized by FTIR, XRD, SEM, XPS, and other methods. The result reveals that the synchronization of polymerization and composite can assure PANI, MnO2, and graphene oxide(GO) form a nanocomposite 3D porous network with uniform dispersion. It exhibits better conductivity, higher discharge voltage (1.46 V average working voltage), lower polarization, and excellent discharge performance (500 ∼ 600 W·h·kg−1 specific energy) in the Mg seawater battery compared with the pressed PANI electrode and AgCl electrode. The PMGO composite cathode overcomes the disadvantage of PANI electrode, and is expected to be used in actual production.