The electrochemical performance of Polyaniline (PANI) can be significantly improved due to the incorporation of spinel-type transition metal oxide, i.e., 1 wt. % of Nickel Ferrite (NiFe 2O 4) into the PANI matrix. In this report, we have synthesised NiFe 2O 4 (NF), PANI1:1 ratio, PANI1:2 ratio, and PANI/NiFe 2O 4 nanocomposites, i.e., PANI1:1/NF1 and PANI1:2/NF2 nanocomposites by in-situ oxidative polymerization method. The conducting network formed in the nanocomposite significantly increases the multiple valence states of the metal for the electrolytic ions. The PANI/NiFe 2O 4 nanocomposite shows good interaction and was confirmed by Fourier Transform Infra-red Spectroscopy (FTIR) and Raman analysis. The SEM analysis reveals a uniformly porous and agglomerated globular morphology of the nanocomposite. Also, the PANI/NiFe 2O 4 composite (PANI1:1/NF1) exhibits enhanced supercapacitive properties due to improve strong conducting path of PANI, which helps to provide the delocalization of the electrons in the polymeric chain. The highest specific capacitance ~ 758 Fg -1 is achieved for PANI 1:1/NF1 sample as compared to bare PANI1:1 (677 Fg -1), PANI1:2 (500 Fg -1), NF (253 Fg -1) and other PANI1:2/NF2 (686 Fg -1) samples at 10 mV/s scan rate in a two-electrode system due to NF nanoparticles filling the vacant places in the polymeric matrix. The energy density (54 Whkg -1), power density (1705 Wkg -1) and good cycling stability approx. 97 % after 10000 GCD cycles of the device is found for PANI1:1/NF1. The EIS studies further confirm that the PANI 1:1/NF1 device has a lower charge transfer resistance (R ct) ~ 0.35 Ohm in comparison to other fabricated devices. It seems that NiFe 2O 4 acts as a “superhighway” for charge transportation between PANI which is beneficial for supercapacitors.
Abstract: Current state-of-the-art Mg-Air batteries or Mg-Air Fuel cells are interchangeably used and involve, Mg-Anode, highly porous carbon cathode as Gas Diffusion Layer (GDL) for air to flow in the cathode and reduces as hydroxyl ion (Oxygen Reduction Reaction) (ORR). The present studies aim at the development of hydroxyl ions doped Conducting Polymer and/or mixed metal oxide phyllosilicates-based cathode for Mg-Air Fuel Cells. This cathode directly supplies OH- ions to the anode for the formation of Mg(OH) 2 and subsequently MgO without involving ORR reaction. Thus, the internal resistance associated with ORR is eliminated and improves the performance of Mg-Air Fuel Cells (FCs). Two cells were fabricated were, Cell 1 with phyllosilicates and Mg-rich phyllosilicate as the cathode and Mg(OH) 2 soaked membrane respectively, Mg anode. Cell 2 with polyaniline cathode, Mg-enriched phyllosilicates as Mg(OH) 2 soaked membrane and Mg anode. The cell configurations are Cell1: SS/Phyllosilicate//Mg(OH)2 soaked Mg-enriched phyllosilicate membrane//Mg/Al Cell2: SS/OH- ions doped Polyaniline//Mg(OH)2 soaked Mg-enriched phyllosilicate membrane//Mg/Al Both the cells were subjected to Galvanostatic Charge/Discharge studies at room temperature at discharge rate of 50mA/g. Cell 1 with naturally occurring mixed oxide silicates (phyllosilicates) performed efficiently then the Cell 2 to conducting polymer cathode.
Microfibrillated cellulose (MFC) with reinforcing effects is a useful building block in the fabrication of flexible and thin supercapacitors. Herein, a hybrid tin oxide-cellulose nanocomposite was hydrothermally produced and coated on MFC thin films to form a supercapacitor. The hybrid tin oxide-cellulose thin films were structurally analyzed using scanning electrode microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. The cellulose thin film with the highest loading of hybrid tin oxide-cellulose nanocomposite exhibited a specific capacitance of 225.88 F/g at 100 mV/s and 486.38 F/g at 20 mV/s in the three-electrode electrochemical system. In addition, it revealed good cyclic stability up to 40 cycles run continuously with 95% cyclic retention. The high specific capacitance and superior cyclic stability could be related to the enhanced charge mobility and ion diffusion between the solid and electrolyte interface. The cellulose thin film coated with flower-like hybrid nanocomposite showed great potential in energy storage.