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The PEAI additive helps in the crystal growth regulation of CsPbI2Br perovskite, which contributes to indoor/outdoor photovoltaic implementation with exceptional conversion efficiency.

Lithium-sulfur battery (LSB) technology has drawn enormous attention during the last decade. Benefitting from the high theoretical specific discharge capacity (1,675 mAh g−1) and energy density (2,600 Wh kg−1), LSBs have proved to be a suitable candidate for electric vehicles and large-scale power grid electrical energy storage systems. However, the commercialization of LSB is hindered by various barriers, which include the high insulating nature of sulfur and its discharge products, severe polysulfide shuttling phenomenon, extreme volume expansion during charging/discharging, and poor stability of Li metal anodes. Additionally, LSB technology faces considerable battery design challenges, which allows high sulfur content and/or sulfur-loading while simultaneously maintaining a low electrolyte/sulfur ratio. Therefore, in this review, we highlight recent effective strategies that lead to more practical and commercial LSBs. We restrict ourselves to various cathode architectures designed specifically to absorb dissolved polysulfide catholyte. The integration of dissolved lithium polysulfide catholyte with specially designed cathode substrates efficiently allows ultra-high sulfur loading and/or sulfur-content with low electrolyte/sulfur ratio while still exhibiting reasonable electrochemical performance and cycling stability. The effect of concentration variation of dissolved lithium polysulfide catholyte on the cell performance is also discussed in detail. Therefore, the present review encapsulates feasible strategies with practical parameters to address the problems associated with LSBs.

Safe and flexible batteries are expected to be the enabler for advancing the technology of wearable electronics to an unforeseen level in near future. However, to date the energy density of such devices is rather limited due to the rather large proportion of dead weight and volume to provide good flexibility. To overcome this hurdle, a disruptive change in the battery manufacturing process is needed. Herein, we not only introduce a simple phase inversion method for the preparation of free-standing and flexible β-Na0.33V2O5 cathodes without metal current collector, but also demonstrate the possibility to integrate those into fully flexible lithium metal batteries. Additionally, employing a LAGP-based hybrid solid electrolyte enables excellent high temperature stability and thus, enhanced safety characteristics of the device. Such integrated flexible batteries exhibit fast and stable lithium-ion storage capabilities, with a large specific capacity of 228 mA h g−1 at 0.1 C and excellent cycling stability translating into an outstanding specific energy of 407.8 Wh kg−1 on electrode level.

A defect structure and osseointegration capacity of sodium and chloride co-substituted hydroxyapatite (NaClAp) were newly studied. The NaClAp was prepared by reacting H3PO4 and Ca(OH)2 with NaNO3 and NH4Cl followed by sintering; pure hydroxyapatite (HAp) was synthesized as a control. After sintering, the co-substitution of Ca and OH with Na and Cl, respectively, produced charged point defects at Ca and PO4 sites. Also, OH molecules partially adopted a head-on structure. The calculated total system energy of NaClAp was higher, whereas the binding energies between each constituent elements and system were lower than those of HAp. These results suggest that NaClAp was less stable than HAp, due to the formation of various defects by co-substitution of Na and Cl. Indeed, NaClAp exhibited higher dissolution behavior in simulated body fluid (SBF) compared with HAp. Accordingly, this increased the capability to produce low crystalline hydroxyl carbonate apatite, likely due to the increasing degree of apatite supersaturation in SBF. Besides, the NaClAp granules showed noticeable improvements in osseointegration capacity four weeks after in vivo test compared with HAp. Collectively, these results imply that the defects made by multiple ion substitutions are useful to increase osseointegration capacity of hydroxyapatite.

The introduction of a functional interlayer between the cathode and anode in lithium–sulfur battery (LSB) technology results in significant improvements in electrochemical performance. Here, we developed hierarchically structured porous, conductive, and multifunctional N-doped carbon (N-C) nanofibers comprising homogeneously dispersed vanadium nitride quantum dots and hollow N-C nanocages as functional interlayers for advanced LSBs. The freestanding interlayer contains well-developed long-range channels and numerous interconnected hollow N-C nanocages derived from the metal–organic framework. Furthermore, the presence of a N-C framework and vanadium nitride quantum dots measuring several nanometers improves the redox reaction kinetics and provides numerous chemisorption sites for the effective trapping and reuse of lithium polysulfide. As a result, the assembled Li–S cell employing the unique nanostructured freestanding interlayer exhibits superior rate capability and stable cycling performance (decay rate of 0.02% per cycle at 0.5C) considering the high sulfur content (80 wt%) and loading (ca. 4 mg cm−2) in the sulfur electrodes. Even with an ultra-high sulfur loading of 11.0 mg cm−2, the Li–S cell delivered a stable areal capacity of 5.0 mA h cm−2 after 100 charge–discharge cycles at 0.05C. Thus, the uniquely nanostructured interlayer shows high potential for the development of advanced LSBs utilizing pure sulfur electrodes with realistic battery parameters.

The relationship between the conformation of a polyelectrolyte and the performance of organic thermoelectric multilayers was studied. The conformational change of a weak polyelectrolyte via controlling assembling pH gave rise to a different thermoelectric behaviour in thin films. Organic thermoelectric multilayers were fabricated by alternately depositing bilayers (BL) of a positively-charged polyaniline (PANi) and multiwalled carbon nanotubes (MWNT), stabilized in poly(acrylic acid) (PAA), via a layer-by-layer assembly technique. The electrical conductivity and See-beck coefficient of PANi/MWNT-PAA nanocomposites were measured by varying assembly pH of PAA solutions. Altering the deposition pH of PAA resulted in different thermoelectric performances. A 40 BL thin film (∼210 nm thick) of PANi/MWNT-PAA assembled at pH 2.5/6.5 exhibited electrical conductivity of 95.2 S/cm and a Seebeck coefficient of 35 µV/K. This translates to a power factor of 11.7 µW/m·K2, which is 50 times higher than that of the same film with all components deposited at pH 2.5. Enhancement of thermoelectric behaviour in PANi/MWNT-PAA nanocomposites is attributed to a conjugated π-π network, together with a tightly packed nanostructure.

Stretchable/flexible electronic devices such as smart electronics, medical instruments, stretchable skin etc. are indeed necessary to make the life of human beings more comfortable. Viability of fully stretchable/flexible electronic equipment heavily relies on development of stretchable/flexible energy storage system. Since electrolyte plays a key role in ion transport and safety of these energy storage systems, stretchability in electrolyte can generate better scope for stretchable/flexible electronic devices as it will provide the greater mechanical sturdiness to the devices while regulating the ion transport. From last few years stretchable electrolytes has become a booming research topic. Thus, this mini review mainly highlights some of the latest works dealing with categories, synthesis strategies and applications of stretchable electrolytes.

Fibrous network of highly-integrated CNTs/MoO3 composite bundle in which CNTs anchored with MoO3 nanoplates was prepared by electrospinning process and subsequent simple heat-treatment. By performing the pre-acid-treatments of both CNTs and PAN, dipole-dipole interactions and hydrogen bonding between CNTs and PAN could form MoO2(acac)2-PAN-CNTs complex in a solution, which allows for the formation of a stable jet during electrospinning. Notably, by selectively removing PAN in as-spun fibers during heat-treatment, a highly integrated CNTs/MoO3 bundle network anchored with MoO3 nanoplates was obtained. This unique CNTs/MoO3 percolation network makes it possible to achieve a superior lithium ion storage performance by improving electrical conductivity and structure stability. Thus, the unique nanostructure has high discharge capacities of 972 mA h g−1 after 100 cycles at 1.0 A g−1 and 905 mA h g−1 after 800 long-term cycles at 2.0 A g−1, when applied as anode materials for lithium-ion batteries. The discharge capacities of 980, 920, 819, 742, 599, 484, and 374 mA h g−1 were observed at current densities of 0.5, 1.0, 2.0, 3.0, 5.0, 7.0, and 10.0 A g−1, respectively.

The development of a suitable cathode host that withstands high sulfur content/loading and low electrolyte/sulfur (E/S) ratio is particularly important for practically sustainable Li-S batteries. Herein, a facile approach is utilized to prepare free-standing 3D cathode substrates comprising nitrogen-doped carbon (N-C) scaffold and metal-organic framework derived interconnected chain-like hollow N-C nanocages, forming a highly porous N-C nanofiber (HP-N-CNF) framework. The N-C skeleton provides highly conductive pathways for fast lithium ion/electron diffusion. The hollow interconnected N-C nanocages not only offer enough space to absorb a high volume of active material but also effectively channelize severe volume stress during the electrochemical performance. The Li-S cell utilizing HP-N-CNF as cathode host displays exceptional battery parameters with high effective sulfur content (83.2 wt%), ultrahigh sulfur loading (14.3 mg cm

In this study, polyethylene oxide (PEO) is introduced into methylammonium lead iodide (MAPbI3) perovskite to replace the standard anti-solvent washing process of perovskite solar cells. By forming PEO-MAPbI3 composites, we achieved controllability of the perovskite surface morphology. Furthermore, the PEO addition improved the electronic properties of the composites by suppressing the trap density of the MAPbI3 perovskite. We observed a significant increase in the average power conversion efficiency (PCE) of the perovskite solar cells (PVSCs) from 0.24% to 7.25% using the proper PEO-perovskite composition ratio (1.5:1), based on their fabrication without any organic anti-solvent treatment. Moreover, the performance uniformity and outdoor stability were significantly enhanced by employing the composite. The proposed PEO-perovskite composite offers a promising pathway for the industrialization of PVSCs in terms of PCE, uniformity, stability, and feasibility—without involving current anti-solvent washing process.

Hierarchical yolk-shell-structured NiCoSe2/CNT [HYS-(NiCo)Se2/CNT] hybrid microspheres consisting of a porous yolk and embossed hollow thin shell were prepared by one-step spray pyrolysis and subsequent selenization heat treatment for potential use as anode materials for sodium-ion batteries. The unique HYS-(NiCo)Se2/CNT microspheres had a hierarchical configuration of an external thin shell, inside porous yolk, and interstitial hollow space. In particular, the porous yolk is composed of CNTs walls and contained interconnected mesopores formed by PS decomposition during one-step spray pyrolysis. The discharge capacity of the HYS-(NiCo)Se2/CNT microspheres was 366 mA h g−1 after 10,000 cycles at a high current density of 3.0 A g−1, and their capacity retention after the 2nd cycle was 85%. The HYS-(NiCo)Se2/CNT microspheres have discharge capacities of 444, 429, 400, 380, 352, 329, 300, 266, 222, and 163 mA h g−1 at current densities of 0.5, 1.0, 2.0, 3.0, 5.0, 7.0, 10.0, 12.0, 15.0 and 20.0 A g−1, respectively. The synergistic effects of the uniquely hierarchical yolk-shell structure, CNTs walls with high electrical conductivity, interstitial mesopores, and anchored (Ni,Co)Se2 nanoparticles resulted in high structural stability during the cycles and excellent sodium-ion storage performance.

This paper introduces a new synthesis strategy suitable for the one-step synthesis of hollow 1-dimensition nanostructures and highly desirable for the simple preparation of well-defined hollow nanostructures with high product yields using camphene. The viscosity gradient of the jet during the electrospinning results in the inward movement of the camphene. Subsequently, the sublimation of camphene generates internal hollow space without further processing. The resulting nanofibers exhibit a reversible discharge capacity of 956 mA h g −1 after 400 cycles when applied as anodes for lithium-ion batteries. The discharge capacities of the nanofibers are 1050, 1024, 937, 796, 643, and 483 mA h g −1 at current densities of 0.5, 1.5, 3.0, 5.0, 7.0, and 10.0 A g −1 , respectively. The NiO nanofibers with hollow structure show high structural stability and shorten the Li + -ion diffusion pathway during cycles, which resulted in excellent lithium-ion storage properties.

Increasing demand for sodium-ion batteries (SIBs), one of the most feasible alternatives to lithium ion batteries (LIBs), has resulted because of their high energy density, low cost, and excellent cycling stability. Consequently, the design and fabrication of suitable electrode materials that govern the overall performance of SIBs are important. Aerosol-assisted spray processes have gained recent prominence as feasible, scalable, and cost-effective methods for preparing electrode materials. Herein, recent advances in aerosol-assisted spray processes for the fabrication of nanostructured metal chalcogenides (e.g., metal sulfides, selenides, and tellurides) for SIBs, with a focus on improving the electrochemical performance of metal chalcogenides, are summarized. Finally, the improvements, limitations, and direction of future research into aerosol-assisted spray processes for the fabrication of various electrode materials are presented.

This paper presents a hierarchical yolk–shell-structured microsphere comprising a hierarchical carbon nanotube (CNT)-(NiCo)O/C yolk and an embossed hollow thin shell (hereafter denoted as CNT-(NiCo)O/C microsphere) prepared by a one-pot spray pyrolysis process for potential use as an anode in lithium-ion batteries. During spray pyrolysis, the hierarchical CNT-(NiCo)O/C yolk, whose frame is linked with CNTs, is formed by mutual binding of the CNTs and size-controlled polystyrene (PS) nanobeads and subsequent selective decomposition of these nanobeads. Further, phase separation of melted poly(vinylpyrrolidone) facilitates the formation of the hollow shell. The discharge capacity of the CNT-(NiCo)O/C microspheres after 1000 cycles at an extremely high current density of 5.0 A g−1 is 598 mA h g−1. The CNT-(NiCo)O/C microspheres show reversible discharge capacities of 886, 709, 509, and 294 mA h g−1 at current densities of 0.5, 5, 20, and 50 A g−1, respectively. The unique nanostructure of the CNT-(NiCo)O/C microspheres with high electrical conductivity promotes the transfer kinetics of electrons and Li+ ions, which consequently leads to their improved electrochemical performances.

For use in next-generation energy storage applications, including electric vehicles, capacity and cycle life of lithium ion batteries need further improvement. Moreover, to achieve fast lithiation kinetics of the electrode materials, high power density and quick charging ability are necessary. Nickel vanadate (Ni3V2O8) microsphere with tens of nanocavities is one of candidates for anode materials suitable for lithium ion batteries. The synthesis of microspheres is possible by a pilot-scale spray drying process and facile one-step oxidation heat treatment. Dextrin, which is present in the microspheres after spray drying process, plays a key role in the formation of nanocavities. Oxidation at different temperatures yields carbon composite microspheres with nanocavities and hierarchical Ni3V2O8 microspheres with nanocavities. The nanocavities facilitate electrolyte contact with the electrode material and alleviate volume change during lithiation/delithiation. The merits of the nanocavities in the Ni3V2O8 microspheres enable a high discharge capacity of 1045 mA h g−1 for the 2nd cycle at 1 A g−1 and long cycle life. Furthermore, Ni3V2O8 microspheres deliver a high discharge capacity of 612 mA h g−1 at a high current density of 6 A g−1.

The asymmetric electrochemical capacitor was realized by MnO2/Vertical graphene nanosheets (VGN) and Fe2O3/VGN as positive and negative electrodes, respectively. The surface of VGN skeleton is independently decorated with MnO2 having sponge gourd-like morphology and Fe2O3 having nanorice like morphology. Both the electrodes have shown around 250 times higher charge-storage capacity than the bare VGN (0.47 mF/cm2) with the specific capacitance of 118 (MnO2/VGN) and 151 mF/cm2 (Fe2O3/VGN). The fabricated asymmetric device exhibited a specific capacitance of 76 mF/cm2 and energy density of 71 μWh/cm2 with an excellent electrochemical stability up to 12,000 cycles, over a potential window of 2.6 V.

Highly integrated and interconnected carbon nanotube (CNT) hybrid nanofibers decorated with α-Fe2O3 (denoted hereafter as HI-CNT/Fe2O3 nanofibers) were first introduced for potential use as freestanding anodes in flexible lithium polymer batteries. CNTs were modified to have a carboxyl group attached. Polyacrylonitrile (PAN) was also hydrolyzed, forming sulfonated polyacrylamide. Dipole–dipole interactions and hydrogen bonding between CNTs and PAN can form Fe(acac)3–PAN–CNT complexes, thus allowing for the formation of highly integrated CNTs in a stable jet without being aggregated during electrospinning. The discharge capacity of a freestanding HI-CNT/Fe2O3 nanofiber anode after 100 cycles at 100 mA g−1 was 651 mA h g−1. The specific capacity of a flexible full-cell combined with a LiFePO4 cathode was maintained at 148.5 mA h g−1 (cathode-based) even after bending for 10 cycles as compared with 148.9 mA h g−1 before bending.

Recently, CsPbI3−xBrx (x = 1–2) all-inorganic perovskites have been studied to overcome the phase instability of CsPbI3. However, the addition of Br inevitably leads to a bandgap that is too wide (1.93–2.03 eV) compared to that of CsPbI3 (1.73 eV). To avoid this, the present study focuses on developing stable α-CsPbI3−xBrx (x < 0.7) perovskite films with lower Br levels. Our dynamic CsBr treatment incorporates Br− into the CsPbI3 lattice, greatly enhancing the morphology, optical properties, stability, and photovoltaic performance of the resultant CsPbI3−xBrx (x < 0.7) perovskite films. At x = 0.66, the perovskite film with the relatively low bandgap of 1.84 eV contributes to achieving an impressive power conversion efficiency (PCE) of 14.08% and, after 1200 h storage under a nitrogen atmosphere without encapsulation, the PCE remains at around 70% of this initial level. This two-step growth using dynamic CsBr treatment opens up promising routes for the feasible fabrication of inorganic perovskite photovoltaics with exceptional stability.