Ranadip Bera

Effect of γ-PVDF on enhanced thermal conductivity and dielectric property of Fe-rGO incorporated PVDF based flexible nanocomposite film for efficient thermal management and energy storage applications

Here, we investigate the effect of thermal conductivity of γ-crystallites of PVDF in Fe-rGO/PVDF nanocomposite, which are of potential use as actuators and temperature sensors for thermal management applications. The formation of γ-crystallites help to increase the thermal conductivity of the nanocomposite up to 0.89 W mK−1 at low level of filler loading (3 wt%) and we showed that the thermal conductivity depends on the amount of crystalline polar γ-phase in addition to filler concentration. Although thermal conductivity depends on the crystallinity of the nanocomposite, here enhancement of thermal conductivity is not related only to crystallinity, as the crystallinity is decreased compared to neat PVDF. However the thermal conductivity increases because of the generation of a higher number of γ-crystallites of small size. Furthermore, the nanocomposite at low filler loading also shows high dielectric constant with low dielectric loss of the order of ≈57 and ≈0.13, respectively, at 1 kHz. Moreover, the energy storage property and its dependence on γ-crystallite size reveals that the material can also exhibit superior released energy density (1.45 J cm−3) as compared to pure PVDF.

An Approach To Fabricate PDMS Encapsulated All-Solid-State Advanced Asymmetric Supercapacitor Device with Vertically Aligned Hierarchical Zn–Fe–Co Ternary Oxide Nanowire and Nitrogen Doped Graphene Nanosheet for High Power Device Applications

We highlight the design and fabrication of a polydimethylsiloxane (PDMS) encapsulated advanced all-solid-state asymmetric supercapacitor (ASC) device consisting of hierarchical mesoporous zinc-iron-cobalt ternary oxide (ZICO) nanowire coated nickel (Ni) foam (ZICO@Ni foam) as a promising positive electrode and nitrogen doped graphene coated Ni foam (N-G@Ni foam) as negative electrode in the presence of PVA-KOH gel electrolyte. Owing to outstanding electrochemical behavior and ultrahigh specific capacitance of ZICO (≈ 2587.4 F/g at 1 A/g) and N-G (550 F/g at 1 A/g) along with their mutual synergistic outputs, the assembled all-solid-state ASC device exhibits an outstanding energy density of ≈40.5 Wh/kg accompanied by a remarkable long-term cycle stability with ≈95% specific capacitance retention even after 5000 charge-discharge cycles. The exclusive hierarchical ZICO nanowires were synthesized by a facile two-step process comprising of a hydrothermal protocol followed by an annealing treatment on a quartz substrate. While Zn2+ gives the stability of the oxide system, Fe and Co ions provide better electronic conductivity and capacitive response under vigorous cyclic condition. The extraordinary performance of as-fabricated ASC device resembles its suitability for the construction of advanced energy storage devices in modern electronic industries.

Single wall carbon nanohorn (SWCNH)/graphene nanoplate/poly(methyl methacrylate) nanocomposites: a promising material for electromagnetic interference shielding applications

Single wall carbon nanohorn (SWCNH)/graphene nanoplates (GNP)/poly(methyl methacrylate) (PMMA) nanocomposites were prepared through addition of GNP/PMMA bead into the SWCNH dispersed PMMA matrix during its polymerization. Three dimensional continuous network of GNP–SWCNH–GNP or SWCNH–GNP–SWCNH has been formed throughout the PMMA matrix outside the GNP/PMMA beads that played a crucial role for high electrical conductivity and electromagnetic interference shielding effectiveness (EMI SE) in the nanocomposites. Thus, high electrical conductivity (4.54 × 10−2 S cm−1) and high EMI SE value ∼(−23.6 dB) were achieved in the nanocomposites even at a low loading of SWCNH and GNP. The ratio of volume (vol%) and weight (wt%) of the all the components (SWCNH : GNP : PMMA) in the final nanocomposites were 1.072 : 0.089 : 98.839 and 1.0 : 0.175 : 98.825, respectively. The GNP/PMMA beads act as excluded volume and also attenuates the microwave energy through multiple reflections. The nonconductive GNP/PMMA beads also create dielectric mismatch which influences the internal multiple reflection property of the nanocomposites.

Fabrication of an advanced asymmetric supercapacitor based on a microcubical PB@MnO2 hybrid and PANI/GNP composite with excellent electrochemical behaviour

Metal Organic Framework (MOF) based supercapacitors are one of the best energy storage devices for future portable electronics. In this study, we report in detail the design and low-cost fabrication of an advanced asymmetric supercapacitor (ASC) which was assembled with a Prussian blue (PB)/MnO2 (PB@MnO2) hybrid as the positive electrode and a polyaniline (PANI)/graphene nanoplatelet (GNP) (PG) composite as the negative electrode with aq. KNO3 electrolyte. Both the electrodes were made by the coating of the respective electrode materials on conducting stainless steel (SS) fabric. The MOF based positive electrode material, i.e., the PB@MnO2 hybrid was synthesized via reducing agent assisted chemical bath deposition of MnO2 nanolayers on faradaic PB microcubes and showed an appreciable specific capacitance (Csp) of 608 F g−1 at 1 A g−1 current density in the three-electrode measurement and the assembled PB@MnO2//PG ASC device manifests favourable Csp of 98 F g−1 at 1 A g−1. Moreover, this ASC device exhibits significant energy density of 16.5 W h Kg−1 at the power density of 550 W Kg−1 along with notable long-term cycling stability (retention of 93% capacitance even after 4000 cycles of charging and discharging). Thus, the obtained results reflect the great potential of the ASC device for exploring state-of-art futuristic applications as an advanced energy storage system.