B. Balamuralitharan

Bio: B. Balamuralitharan is an academic researcher from Pusan National University. The author has contributed to research in topics: Supercapacitor & Electrode. The author has an hindex of 8, co-authored 8 publications receiving 246 citations.

Phase transition kinetics and surface binding states of methylammonium lead iodide perovskite.

Abstract: We have presented a detailed analysis of the phase transition kinetics and binding energy states of solution processed methylammonium lead iodide (MAPbI3) thin films prepared at ambient conditions and annealed at different elevated temperatures. It is the processing temperature and environmental conditions that predominantly control the crystal structure and surface morphology of MAPbI3 thin films. The structural transformation from tetragonal to cubic occurs at 60 °C with a 30 minute annealing time while the 10 minute annealed films posses a tetragonal crystal structure. The transformed phase is greatly intact even at the higher annealing temperature of 150 °C and after a time of 2 hours. The charge transfer interaction between the Pb 4f and I 3d oxidation states is quantified using XPS.

V2O5 nanorod electrode material for enhanced electrochemical properties by a facile hydrothermal method for supercapacitor applications

Abstract: Metal oxides have attracted considerable interest due to their distinguished electrochemical properties and applications in multiple fields such as supercapacitors and solar cells. It is beneficial to exploit V2O5 electrode materials with desired structures as well as potential applications due to their low-cost, low toxicity, wide voltage windows and multiple oxidation states. A facile hydrothermal method for synthesizing V2O5 nanorods using ammonium metavanadate with an acidic reducing agent at 200 °C is reported. The surface morphology, crystallinity and functional group modifications of the nanorods are analyzed by scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray analysis. V2O5 nanorods on stainless steel (SS) plate architecture exhibit an outstanding electrochemical performance in supercapacitors with high areal specific capacitance of 417.4 mF cm−2 at a scan rate of 5 mV s−1, excellent rate capability, and good cycling stability for 5000 cycles in 0.5 M sodium sulfate in comparison to the observations in 0.5 M sulfuric acid and 0.5 M KCl electrolytes. Moreover, a three electrode setup is used to scrutinize the electrochemical performance of the V2O5-nanorod electrode; it shows superior performance in terms of high areal specific capacitance, which is the highest reported value so far, and it also shows long cycling stability. Our study demonstrates that the as-fabricated V2O5 nanorods can be applied in both high energy density fields and high power density applications such as flexible electronics, electric vehicles and energy storage devices.

Novel high-temperature supercapacitor combined dye sensitized solar cell from a sulfated β-cyclodextrin/PVP/MnCO3 composite

Abstract: A novel sulfated β-cyclodextrin/PVP/MnCO3 composite has been synthesized for a parallel-connected supercapacitor and dye-sensitized solar cell (counter electrode). β-Cyclodextrin has sulfonated, thermally cross-linked with PVP, and incorporated with MnCO3 nanoparticles. The composite electrode exhibited 202.6 F g−1 capacitance, 197.96 W h kg−1 energy density, 5.57% η (DSSC) and 70% performance up to 200 °C with a [BMI][TFSI] electrolyte.

Hybrid Reduced Graphene Oxide/Manganese Diselenide Cubes: A New Electrode Material for Supercapacitors

Abstract: The integration of 2 D graphene nanosheets and layered transition-metal dichalcogenides has been recognized as one of the most extensive strategies for the synthesis of promising electrode materials for energy-storage devices. In this study, cubic manganese diselenide (MnSe2) and hybrid reduced graphene oxide/MnSe2 (G-MnSe2) materials were synthesized by a facile hydrothermal method. Metallic selenium impurities are considered to be a major unwanted byproduct in this method. An effective means to remove such bulk chalcogenides is a key challenge. For the synthesis of the G-MnSe2 hybrid material, we used a strategy in which the graphene oxide was mixed with manganese and selenium precursors. Surprisingly, the final G-MnSe2 product contained a negligible amount of selenium impurity. The MnSe2 and G-MnSe2 hybrid materials were characterized in detail. For the first time, the electrochemical energy-storage behavior of MnSe2-based materials was assessed for supercapacitor applications. The specific capacitance of the MnSe2 electrode was approximately 57.8 mF cm−2, whereas the hybrid G-MnSe2 electrode showed a much higher specific capacitance of 93.3 mF cm−2 at a scan rate of 1 mV s−1. A symmetric cell made from the G-MnSe2 hybrid material showed excellent long-term stability for 4500 cycles and approximately 106 % retention of its initial capacitance, which is impressive compared with the cycle life of the MnSe2-based symmetric cell (80 % capacitance retention at the 4500th cycle).

Electrolyte-imprinted graphene oxide–chitosan chelate with copper crosslinked composite electrodes for intense cyclic-stable, flexible supercapacitors

Abstract: Electrolyte-imprinted and copper crosslinked hybrid flexible electrodes have been considered as long-term stability supercapacitors. Graphene oxide, chitosan and copper (copper chloride) were crosslinked under ionic liquid medium using a hydrothermal technique. The fabricated flexible supercapacitor exhibits a maximum 356 F g−1 specific capacitance and possesses extreme cyclic stability up to 200000 cycles.

Ultracapacitors: Why, How, and Where is the Technology

Abstract: The science and technology of ultracapacitors are reviewed for a number of electrode materials, including carbon, mixed metal oxides, and conducting polymers. More work has been done using microporous carbons than with the other materials and most of the commercially available devices use carbon electrodes and an organic electrolytes. The energy density of these devices is 3¯5 Wh/kg with a power density of 300¯500 W/kg for high efficiency (90¯95%) charge/discharges. Projections of future developments using carbon indicate that energy densities of 10 Wh/kg or higher are likely with power densities of 1¯2 kW/kg. A key problem in the fabrication of these advanced devices is the bonding of the thin electrodes to a current collector such the contact resistance is less than 0.1 cm2. Special attention is given in the paper to comparing the power density characteristics of ultracapacitors and batteries. The comparisons should be made at the same charge/discharge efficiency.

Compound Copper Chalcogenide Nanocrystals

Abstract: This review captures the synthesis, assembly, properties, and applications of copper chalcogenide NCs, which have achieved significant research interest in the last decade due to their compositional and structural versatility. The outstanding functional properties of these materials stems from the relationship between their band structure and defect concentration, including charge carrier concentration and electronic conductivity character, which consequently affects their optoelectronic, optical, and plasmonic properties. This, combined with several metastable crystal phases and stoichiometries and the low energy of formation of defects, makes the reproducible synthesis of these materials, with tunable parameters, remarkable. Further to this, the review captures the progress of the hierarchical assembly of these NCs, which bridges the link between their discrete and collective properties. Their ubiquitous application set has cross-cut energy conversion (photovoltaics, photocatalysis, thermoelectrics), en...

Flexible electrodes and supercapacitors for wearable energy storage: a review by category

Abstract: Supercapacitors are important energy storage devices capable of delivering energy at a very fast rate. With the increasing interest in portable and wearable electronic equipment, various flexible supercapacitors (FSCs) and flexible electrodes (FEs) have been investigated widely and constantly in recent years. Currently-developed FEs/FSCs exhibit myriad physical forms and functional features and form a complicated and extensive system. Herein, we summarize the recent results about FEs/FSCs and present this review by categories. According to different micro-structures and macroscopic patterns, the existing FEs/FSCs can be divided into three types: fiber-like FEs/FSCs; paper-like FEs/FSCs; and three-dimensional porous FEs (and corresponding FSCs). Subsequently each type of the FEs/FSCs is further sub-classified based on their construction rules, and mechanical and electrochemical properties. To our best knowledge, this is the first time such a hierarchical and detailed classification strategy has been propose. We believe it will be beneficial for researchers around the world to understand FEs/FSCs. In addition, we bring up some fresh ideas for the future development of wearable energy storage devices.

Trapped charge-driven degradation of perovskite solar cells

Abstract: Perovskite solar cells have shown unprecedent performance increase up to 22% efficiency. However, their photovoltaic performance has shown fast deterioration under light illumination in the presence of humid air even with encapulation. The stability of perovskite materials has been unsolved and its mechanism has been elusive. Here we uncover a mechanism for irreversible degradation of perovskite materials in which trapped charges, regardless of the polarity, play a decisive role. An experimental setup using different polarity ions revealed that the moisture-induced irreversible dissociation of perovskite materials is triggered by charges trapped along grain boundaries. We also identified the synergetic effect of oxygen on the process of moisture-induced degradation. The deprotonation of organic cations by trapped charge-induced local electric field would be attributed to the initiation of irreversible decomposition.

A piperidinium salt stabilizes efficient metal-halide perovskite solar cells.

Abstract: Longevity has been a long-standing concern for hybrid perovskite photovoltaics. We demonstrate high-resilience positive-intrinsic-negative perovskite solar cells by incorporating a piperidinium-based ionic compound into the formamidinium-cesium lead-trihalide perovskite absorber. With the bandgap tuned to be well suited for perovskite-on-silicon tandem cells, this piperidinium additive enhances the open-circuit voltage and cell efficiency. This additive also retards compositional segregation into impurity phases and pinhole formation in the perovskite absorber layer during aggressive aging. Under full-spectrum simulated sunlight in ambient atmosphere, our unencapsulated and encapsulated cells retain 80 and 95% of their peak and post-burn-in efficiencies for 1010 and 1200 hours at 60° and 85°C, respectively. Our analysis reveals detailed degradation routes that contribute to the failure of aged cells.