We report a new class of Zn anodes modified by a three-dimensional nanoporous ZnO architecture (Zn@ZnO-3D), which can accelerate the kinetics of Zn2+ transfer and deposition, inhibit dendrite growth, and reduce the side-reactions.
Sodium-ion capacitors can potentially combine the virtues of high power capability of conventional electrochemical capacitors and high energy density of batteries. However, the lack of high-performance electrode materials has been the major challenge of sodium-based energy storage devices. In this work, we report a microwave-assisted synthesis of single-crystal-like anatase TiO mesocages anchored on graphene as a sodium storage material. The architecture of the nanocomposite results in pseudocapacitive charge storage behavior with fast kinetics, high reversibility, and negligible degradation to the micro/nanostructure. The nanocomposite delivers a high capacity of 268 mAh g at 0.2 C, which remains 126 mAh g at 10 C for over 18 000 cycles. Coupling with a carbon-based cathode, a full cell of sodium-ion capacitor successfully demonstrates a high energy density of 64.2 Wh kg at 56.3 W kg and 25.8 Wh kg at 1357 W kg, as well as an ultralong lifespan of 10 000 cycles with over 90% of capacity retention.
Layered oxide LiNi x Co y Mn z O 2 (0 < x,y,z < 1, x + y + z = 1) or NCM is becoming the dominating cathode material in high-energy lithium-ion batteries (LIBs), which have degradation issues after cycling due to Li loss and phase changes. Directly resolving these issues to generate new cathodes cannot only reduce the high cost but also prevent environmental pollution from disposal of used LIBs. However, currently there is no effective approach to tackle this challenge. Here we demonstrate a nondestructive process to directly regenerate degraded NCM cathode particles to obtain new active particles. Using this method, nearly ideal stoichiometry, low cation mixing, and high phase purity were achieved in the regenerated NCM particles, which offer high specific capacity, good cycling stability, and high rate capability, all reaching pristine materials. Our work represents a simple yet efficient approach to directly regenerate high-performance NCM cathodes with distinct advantages over traditional hydrometallurgical methods and builds an important foundation for the sustainable manufacturing of energy materials.
A green, simple and energy-efficient strategy that combines hydrothermal treatment and short thermal annealing has been developed to recycle and regenerate faded lithium ion battery cathode materials with high electrochemical performance.
Novel composite separators containing metal–organic‐framework (MOF) particles and poly(vinyl alcohol) are fabricated by the electrospinning process. The MOF particles containing opened metal sites can spontaneously adsorb anions while allowing effective transport of lithium ions in the electrolyte, leading to dramatically improved lithium‐ion transference number tLi+ (up to 0.79) and lithium‐ion conductivity. Meanwhile, the incorporation of the MOF particles alleviates the decomposition of the electrolyte, enhances the electrode reaction kinetics, and reduces the interface resistance between the electrolyte and the electrodes. Implementation of such composite separators in conventional lithium‐ion batteries leads to significantly improved rate capability and cycling durability, offering a new prospective toward high‐performance lithium‐ion batteries.
The use of semiconductor nanocrystal quantum dots (QDs) in optoelectronic devices typically requires postsynthetic chemical surface treatments to enhance electronic coupling between QDs and allow for efficient charge transport in QD films. Despite their importance in solar cells and infrared (IR) light-emitting diodes and photodetectors, advances in these chemical treatments for lead chalcogenide (PbE; E = S, Se, Te) QDs have lagged behind those of, for instance, II-VI semiconductor QDs. Here, we introduce a method for fast and effective ligand exchange for PbE QDs in solution, resulting in QDs completely passivated by a wide range of small anionic ligands. Due to electrostatic stabilization, these QDs are readily dispersible in polar solvents, in which they form highly concentrated solutions that remain stable for months. QDs of all three Pb chalcogenides retain their photoluminescence, allowing for a detailed study of the effect of the surface ionic double layer on electronic passivation of QD surfaces, which we find can be explained using the hard/soft acid-base theory. Importantly, we prepare highly conductive films of PbS, PbSe, and PbTe QDs by directly casting from solution without further chemical treatment, as determined by field-effect transistor measurements. This method allows for precise control over the surface chemistry, and therefore the transport properties of deposited films. It also permits single-step deposition of films of unprecedented thickness via continuous processing techniques, as we demonstrate by preparing a dense, smooth, 5.3-μm-thick PbSe QD film via doctor-blading. As such, it offers important advantages over laborious layer-by-layer methods for solar cells and photodetectors, while opening the door to new possibilities in ionizing-radiation detectors.
A new nanocomposite formulation of the FeS-based anode for lithium-ion batteries is proposed, where FeS nanoparticles wrapped in reduced graphene oxide (RGO) are produced via a facile direct-precipitation approach. The resulting nanocomposite FeS@RGO structure has better lithium ion storage properties, exceeding those of FeS prepared without RGO sheets. The enhanced electrochemical performance is attributed to the robust sheet-wrapped structure with smaller FeS nanoparticles and synergetic effects between FeS and RGO sheets, such as increased conductivity, shortened lithium ion diffusion path, and the effective prevention of polysulfide dissolution.
For the past five years, nanostructured niobium-based oxides have emerged as one of the most prominent materials for batteries, supercapacitors, and fuel cell technologies, for instance, TiNb2O7 as an anode for lithium-ion batteries (LIBs), Nb2O5 as an electrode for supercapacitors (SCs), and niobium-based oxides as chemically stable electrochemical supports for fuel cells. Their high potential window can prevent the formation of lithium dendrites, and their rich redox chemistry (Nb(5+)/Nb(4+), Nb(4+)/Nb(3+)) makes them very promising electrode materials. Their unique chemical stability under acid conditions is favorable for practical fuel-cell operation. In this review, we summarized recent progress made concerning the use of niobium-based oxides as electrodes for batteries (LIBs, sodium-ion batteries (SIBs), and vanadium redox flow batteries (VRBs)), SCs, and fuel cell applications. Moreover, crystal structures, charge storage mechanisms in different crystal structures, and electrochemical performances in terms of the specific capacitance/capacity, rate capability, and cycling stability of niobium-based oxides are discussed. Insights into the future research and development of niobium-based oxide compounds for next-generation electrochemical devices are also presented. We believe that this review will be beneficial for research scientists and graduate students who are searching for promising electrode materials for batteries, SCs, and fuel cells.
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