In the present work, an eco-friendly and low-cost lithium-ion full cell assembled using Mn<sub>3</sub>O<sub>4</sub>-mesoporous (MnMC) composite anode and LiFePO<sub>4</sub> cathode (LFP) is investigated for energy storage applications. Hydrothermally synthesized Mn<sub>3</sub>O<sub>4</sub> nanoflakes with a length of 40-50 nm are physically mixed with mesoporous carbon (MC) to obtain MnMC nanocomposite, and sol-gel method in the presence of citric acid is employed to synthesize the cathode material LiFePO<sub>4</sub>. The structural and morphological details of LFP cathode are investigated using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) techniques and the electrochemical performance is evaluated by assembling half cells with lithium metal as the counter electrode. The MnMC nanocomposite is pre-lithiated and combined with LFP cathode for the full lithium ion cell with a cathode limiting capacity. The LFP-MnMC full cells exhibit reversible capacity of the LFP cathode and show good cycling stability with a capacity retention of 66% and the average Coulombic efficiency is found to be 98% after 100 cycles.
Carbon material derived from biomass is used to modify the sulfur cathode. The modified sulfur cathode composite (ACS) together with PEDOT: PSS-CNT interlayer is used to visualize high performance Li-S cells. The Li-S cells with the interlayer inserted between the separator and ACS cathode shows remarkably improved electrochemical activity with an initial discharge capacity of 950 mA h g<sup>-1</sup> at 0.2 C. The improved performance for the interlayer assisted Li-S cells is due to the conductivity of the interlayer, also it can hold back the migrating polysulfides with in the cathode region and hindering the polysulfide shuttling phenomenon.
Supercapacitors (SCs) have got much attention in energy storage devices because of their higher power densities, fast charge-discharge processes, and extended cycle life. Conjugated polymers such as polyaniline (PANI) are widely used for the supercapacitor electrode applications due to its chemical stability, high conductivity, cost-effectiveness and ease of synthesis. PANI/multiwalled carbon nanotube (MWCNT) composite was synthesized via in-situ polymerization method. Morphological studies confirmed the formation of PANI/MWCNT composite. Detailed electrochemical characterization was carried out with aluminum and carbon cloth (CC) as a current collector for the fabrication of SC. PANI/MWCNT composite shows a specific capacitance of 0.02 F/g and 158.4 F/g using aluminum and carbon cloth as current collector, respectively, at a current density of 1 A/g within the potential range of 0 to 1 V in 1M lithium perchlorate electrolyte. The Charge storage in PANI/MWCNT composite SC is a combination of pseudocapacitance and electrical double layer capacitance. PANI/MWCNT composite with CC as current collector reaches a specific capacitance of ~174 F/g at a current density of 0.5 A/g. With the CC current collector, the composite electrode shows high cycling stability for more than 1000 cycles. Fiber-like 3D structure improves the surface area of the electrode and thereby increases the performance of the electrode in terms of cycling stability. The result shows that the synthesized binary composite is a promising electrode material for supercapacitor applications.
In the present work, attempts have been made to embed Silver (Ag) /Gold (Au) - nanoparticles into polyaniline (PANI)
matrix using an easy wet chemical route. It is expected that the resulting nanocomposite will show the interesting third
order nonlinear optical characteristics of Ag/Au-nanoparicles modified by the advantageous properties of the conducting
polymer PANI. Structural characterisation of Ag/Au-PANI nanocomposite samples was done using X-ray diffraction
and Raman studies. UV-visible absorption spectra show the presence of surface plasmon resonance (SPR) peaks centred
at 410 nm and 520 nm for Ag-PANI and Au-PANI nanocomposite films respectively, which is a signature of nano
dimensionality of the composite samples. Third order nonlinear behaviour of the nanocomposite films was analysed
using Z Scan technique employing the second harmonic output (532 nm) of a Q-switched Nd:YAG laser (Minilite,
Continuum). It is seen that Ag/Au-PANI nanocomposite film samples show simultaneous presence of saturable
absorption (SA) and reversible saturable absorptions (RSA) behaviour at 50 μJ laser excitation. This switching between
SA and RSA has been reported in many metal nanocomposite systems. However similar behavior in nanocomposite film
samples has not been pursued much. The highlight of the present work is the observation of the switching between SA
and RSA in Ag/Au polyaniline nanocomposite films. The switching behavior can be ascribed to the interplay between
ground state plasmon band bleaching and excited state absorption. Two photon assisted absorption has been identified as
the prime factor contributing towards the observed RSA in these nanocomposite films.
The present work highlights the prospects of application of the nanocomposite, polyaniline (PANI) -
polyvinylchloride(PVC)- Multi Walled Carbon Nanotube (MWNT), in pressure sensing devices. The above
nanocomposite sample in the form of pressed pellet shows orders of change in electrical conductivity with applied
pressure in the range 10E5 Pa to 10E9 Pa, even for very small applied bias of a few milli-volts. The percentage variation
of electrical conductivity with applied pressure is strikingly large for this composite. There is ample scope for further
investigations in this direction especially if the samples can be cast in the form of free-standing films.