Lithium–sulfur (Li–S) chemistry is projected to be one of the most promising for next-generation battery technology, and controlling the inherent “polysulfide shuttle” process has become a key ...research topic in the field. Regulating intermediary polysulfide dissolution by understanding the metamorphosis is essential for realizing stable and high-energy-density Li–S batteries. As of yet, a clear consensus on the basic surface/interfacial properties of the sulfur electrode has not been achieved, although the catalytic phenomenon has been shown to result in enhanced cell stability. Herein, we present evidence that the polysulfide shuttle in a Li–S battery can be stabilized by using electrocatalytic transition metal dichalcogenides (TMDs). Physicochemical transformations at the electrode/electrolyte interface of atomically thin monolayer/few-layer TMDs were elucidated using a combination of spectroscopic and microscopic analysis techniques. Preferential adsorption of higher order liquid polysulfides and subsequent conversion to lower order solid species in the form of dendrite-like structures on the edge sites of TMDs have been demonstrated. Further, detailed electrochemical properties such as activation energy, exchange current density, rate capabilities, cycle life, etc. have been investigated by synthesizing catalytically active nanostructured TMDs in bulk quantity using a liquid-based shear-exfoliation method. Unveiling a specific capacity of 590 mAh g–1 at 0.5 C rate and stability over 350 cycles clearly indicates yet another promising application of two-dimensional TMDs.
With the unique‐layered structure, MXenes show potential as electrodes in energy‐storage devices including lithium‐ion (Li+) capacitors and batteries. However, the low Li+‐storage capacity hinders ...the application of MXenes in place of commercial carbon materials. Here, the vanadium carbide (V2C) MXene with engineered interlayer spacing for desirable storage capacity is demonstrated. The interlayer distance of pristine V2C MXene is controllably tuned to 0.735 nm resulting in improved Li‐ion capacity of 686.7 mA h g−1 at 0.1 A g−1, the best MXene‐based Li+‐storage capacity reported so far. Further, cobalt ions are stably intercalated into the interlayer of V2C MXene to form a new interlayer‐expanded structure via strong V–O–Co bonding. The intercalated V2C MXene electrodes not only exhibit superior capacity up to 1117.3 mA h g−1 at 0.1 A g−1, but also deliver a significantly ultralong cycling stability over 15 000 cycles. These results clearly suggest that MXene materials with an engineered interlayer distance will be a rational route for realizing them as superstable and high‐performance Li+ capacitor electrodes.
The interlayer spacing and coordination of V2C MXenes are engineered via atomic cobalt covalent bonding. The obtained V2C electrode with tuned 0.735 nm interlayer spacing delivers the best MXene‐based Li+‐storage capacity reported so far. The Co‐intercalated V2C electrode exhibits a superior capacity (1117.3 mA h g−1, higher than theoretical values of V2C) and ultralong cycling stability (over 15 000 cycles).
Solar‐assisted electrochemical desalination has offered a new energy–water nexus technology for sustainable development in recent studies. However, only a few reports have demonstrated insufficient ...photocurrent, a low salt removal rate, and poor stability. In this study, a high‐quality freshwater level of 5–10 ppm (from an initial feed of 10 000 ppm), an enhanced salt removal rate (217.8 µg cm−2 min−1 of NaCl), and improved cycling and long‐term stability are achieved by integrating dye‐sensitized solar cells (DSSCs) and redox‐flow desalination (RFD) under light irradiation without additional electrical energy consumption. The DSSC redox electrolyte (I−/I3−) is circulated between the photoanode (N719/TiO2) and intermediate electrode (graphite paper). Two DSSCs in parallel or series connections are directly coupled to the RFD device. Overall, this hybrid system can be used to boost photo electrochemical desalination technology. The energy–water nexus technology will open a new route for dual‐role devices with photodesalination functions without energy consumption and solar‐to‐electricity generation.
Flow‐based dye‐sensitized solar cell is directly integrated with redox‐flow desalination device to achieve high performance of photo‐desalination. A high‐quality water product of 5 ppm is obtained from the initial salt feed concentration of 10 000 ppm. The salt removal rate is up to 209.7 µg cm−2 min−1.
Cost effective modes of transport keeping in conjunction with sustainable outlooks for the future have ensured new technologies and initiatives being taken across the globe. Lighter electric vehicles ...including two-wheelers or scooters have risen in popularity, with both government and private backed industries investing heavily in green energy. Various state of the art energy systems has been discussed, along with unique approaches to ensure optimum efficiency and lifetime, such as preventing thermal runway reactions, and minimal degradation of electrodes. Supercapacitors, and hybrid fuel cells show potential to be adapted on large scale. New materials and approaches to synthesising the former have also been addressed, with emphasis on the powering of the next generation vehicles. Hybrid motor and engine setups developed over the last several years show great improvement and consume minimal quantity of energy. Clever braking technologies further showcase regenerative techniques and improve mileage. Fuel cost comparisons and recycling methodologies are seen to be researched extensively, while multiple challenges have been addressed. Major problems such as reducing carbon footprints and minimising several particulate pollutions present in the atmosphere are demonstrated to be overcome by implementation of electric two wheelers with regions like Europe and Asia showing the most promise in current times. This review will aim to integrate the individual functions and piece the whole system together. Analysis of future opportunities will allow for a comprehensive overview as well.
Polymer dielectrics find applications in modern electronic and electrical technologies due to their low density, durability, high dielectric breakdown strength, and design flexibility. However, they ...are not reliable at high temperatures due to their low mechanical integrity and thermal stability. Herein, a self‐assembled dielectric nanocomposite is reported, which integrates 1D polyaramid nanofibers and 2D boron nitride nanosheets through a vacuum‐assisted layer‐by‐layer infiltration process. The resulting nanocomposite exhibits hierarchical stacking between the 2D nanosheets and 1D nanofibers. Specifically, the 2D nanosheets provide a thermally conductive network while the 1D nanofibers provide mechanical flexibility and robustness through entangled nanofiber–nanosheet morphologies. Experiments and density functional theory show that the nanocomposites through thickness heat transfer processes are nearly identical to that of boron nitride due to synergistic stacking of polyaramid units onto boron nitride nanosheets through van der Waals interactions. The nanocomposite sheets outperform conventional dielectric polymers in terms of mechanical properties (about 4–20‐fold increase of stiffness), light weight (density ≈1.01 g cm−3), dielectric stability over a broad range of temperature (25–200 °C) and frequencies (103–106 Hz), good dielectric breakdown strength (≈292 MV m−1), and excellent thermal management capability (about 5–24 times higher thermal conductivity) such as fast heat dissipation.
A thermally conductive dielectric nanocomposite with mechanical flexibility and robustness and temperature stability is developed by integrating 1D polyaramid nanofibers and 2D boron nitride nanosheets for next‐generation electronic device and electric power systems.
The burgeoning energy demands of an increasingly eco-conscious population have spurred the need for sustainable energy storage devices, and have called into question the viability of the popular ...lithium ion battery. A series of natural polyaromatic compounds have previously displayed the capability to bind lithium
polar oxygen-containing functional groups that act as redox centers in potential electrodes. Lawsone, a widely renowned dye molecule extracted from the henna leaf, can be dimerized to bislawsone to yield up to six carbonyl/hydroxyl groups for potential lithium coordination. The facile one-step dimerization and subsequent chemical lithiation of bislawsone minimizes synthetic steps and toxic reagents compared to existing systems. We therefore report lithiated bislawsone as a candidate to advance non-toxic and recyclable green battery materials. Bislawsone based electrodes displayed a specific capacity of up to 130 mA h g
at 20 mA g
currents, and voltage plateaus at 2.1-2.5 V, which are comparable to modern Li-ion battery cathodes.
Fabrication of lithium-ion batteries that operate from room temperature to elevated temperatures entails development and subsequent identification of electrolytes and electrodes. Room temperature ...ionic liquids (RTILs) can address the thermal stability issues, but their poor ionic conductivity at room temperature and compatibility with traditional graphite anodes limit their practical application. To address these challenges, we evaluated novel high energy density three-dimensional nano-silicon electrodes paired with 1-methyl-1-propylpiperidinium bis(trifluoromethanesulfonyl)imide (Pip) ionic liquid/propylene carbonate (PC)/LiTFSI electrolytes. We observed that addition of PC had no detrimental effects on the thermal stability and flammability of the reported electrolytes, while largely improving the transport properties at lower temperatures. Detailed investigation of the electrochemical properties of silicon half-cells as a function of PC content, temperature, and current rates reveal that capacity increases with PC content and temperature and decreases with increased current rates. For example, addition of 20% PC led to a drastic improvement in capacity as observed for the Si electrodes at 25 °C, with stability over 100 charge/discharge cycles. At 100 °C, the capacity further increases by 3–4 times to 0.52 mA h cm–2 (2230 mA h g–1) with minimal loss during cycling.
Coherent nonlinear spectroscopies and imaging in the X-ray domain provide direct insight into the coupled motions of electrons and nuclei with resolution on the electronic length scale and timescale. ...The experimental realization of such techniques will strongly benefit from access to intense, coherent pairs of femtosecond X-ray pulses. We have observed phase-stable X-ray pulse pairs containing more than 3 × 107 photons at 5.9 keV (2.1 Å) with ∼1 fs duration and 2 to 5 fs separation. The highly directional pulse pairs are manifested by interference fringes in the superfluorescent and seeded stimulated manganese Kα emission induced by an X-ray free-electron laser. The fringes constitute the time-frequency X-ray analog of Young’s double-slit interference, allowing for frequency domain X-ray measurements with attosecond time resolution.
Nature-inspired solutions to energy storage are aimed at sustainability, cost-efficiency, and humanitarian issues surrounding current lithium ion battery (LIB) technologies. Tetrakislawsone (TKL), a ...tetramer derived from the natural tattooing dye henna, yields a promising cathode material for recyclable and environmentally friendly LIBs. Previously, small organic molecules as LIB materials have displayed precipitous capacity fading and poor cycling lifetimes due to their instability in organic electrolytes. Our study finds that tetrakislawsone exhibits stable gravimetric capacities exceeding 100 mAh g–1 for over 300 charge/discharge cycles owed to the coordination of four Li ions as well as the unique stability of lithium salts of TKL in electrolytes. The mechanistic investigation of metal ion binding was aided by DFT computations, solid-state NMR, and in situ spectroscopy studies revealing that the molecule adopts a nonplanar coordination geometry. This allows for reversible lithium ion binding between the carbonyl and hydroxyl functional groups of TKL subunits.
Li-S batteries still suffer from two of the major challenges: polysulfide shuttle and low inherent conductivity of sulfur. Here, we report a facile way to develop a bifunctional separator coated with ...fluorinated multiwalled carbon nanotubes. Mild fluorination does not affect the inherent graphitic structure of carbon nanotubes as shown by transmission electron microscopy. Fluorinated carbon nanotubes show an improved capacity retention by trapping/repelling lithium polysulfides at the cathode, while simultaneously acting as the "second current collector". Moreover, reduced charge-transfer resistance and enhanced electrochemical performance at the cathode-separator interface result in a high gravimetric capacity of around 670 mAh g
at 4C. Unique chemical interactions between fluorine and carbon at the separator and the polysulfides, studied using DFT calculations, establish a new direction of utilizing highly electronegative fluorine moieties and absorption-based porous carbons for mitigation of polysulfide shuttle in Li-S batteries.
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