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Post-lithium-ion batteries (LIBs) have been widely studied owing to the extensive exploitation of lithium resources. Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) are considered su...

Transition-metal sulfides have been extensively studied as anode materials for use in sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) due to their multi-electron reactions, high rate performance, and abundant available resources. However, the practical capacities of metal sulfides remain low due to conductivity issues, volume expansion, and the use of traditional carbonate electrolytes. To overcome these drawbacks, ether electrolytes can be combined with nanoparticle-based metal sulfide anodes. Herein, a nanoparticle-based nickel monosulfide (NiS) anode with high rate performance in the ether electrolytes of SIBs/PIBs was prepared by heating a mixture of nickel nanoparticles with sulfur. In SIBs, the NiS anode capacity was 286 mA h g-1 at a high current density of 100 A g-1, and excellent cycling performance was observed at 25 A g-1 with a capacity of 468 mA h g-1 after 1000 cycles. Moreover, a full-cell containing a Na3V2(PO4) cathode demonstrated a rate performance of 65 mA h g-1 at a high current density of 100 A g-1. In PIBs, the NiS electrode capacity was 642 and 37 mA h g-1 at 0.5 and 100 A g-1, respectively. Hence, the synthesised NiS nanoparticles possessed excellent storage capability, regardless of the alkali-ion type, suggesting their potential use as robust NiS anodes for advanced battery systems.

Transition metal oxide materials with high theoretical capacities have been studied as substitutes for commercial graphite in lithiumion batteries. Among these, SnO2 is a promising alloying reaction-based anode material. However, the problem of rapid capacity fading in SnO2 due to volume variation during the alloying/dealloying processes must be solved. The lithiation of SnO2 results in the formation of a Li2O matrix. Herein, the volume variation of SnO2 was suppressed by controlling the voltage window to 1 V to prevent the delithiation reaction between Li2O and Sn. Using this strategy the unreacted Li2O matrix was enriched with metallic Sn particles, thereby providing a pathway for lithium ions. The specific capacity decay in the voltage window of 0.05–3 V was 1.8% per cycle. However, the specific capacity decay was improved to 0.04% per cycle after the voltage window was restricted (in the range of 0.05–1 V). This strategy resulted in a specific capacity of 374.7 mAh g−1 at 0.1 C after 40 cycles for the SnO2 anode.

In this work, the hydrothermal method was employed to produce SnO2/rGO as anode material. Nanostructured SnO2 was prepared to enhance reversibility and to deal with the undesirable volume changes during cycling. The SnO2/rGO hybrid exhibits long cycle life in lithium-ion storage capacity and rate capability with an initial discharge capacity of 1327 mAh/g at 0.1 C rate. These results demonstrate that a fabricated SnO2/rGO matrix will be a possible way to obtain high rate performance.

Owing to the speculated price hike and scarcity of lithium resources, sodium-ion batteries are attracting significant research interest these days. However, sodium-ion battery anodes do not deliver good electrochemical performance, particularly rate performance. Herein, we report the facile electrospinning synthesis of a free-standing nickel disulfide (NiS2) embedded on carbon nanofiber. This electrode did not require a conducting agent, current collector, and binder, and typically delivered high capacity and rate performance. The electrode delivered a high initial capacity of 603 mAh g−1 at the current density of 500 mA g−1. Moreover, the electrode delivered the capacity of 271 mAh g−1 at the high current density of 15 A g−1. The excellent rate performance and high coulombic efficiency of the electrode were attributed to its low charge transfer resistance and unique structure.

Sulfurized polyacrylonitrile (S-PAN) is one of the best materials for addressing some of the intrinsic drawbacks of lithium–sulfur batteries, such as the intrinsic insulating properties of sulfur and the shuttle phenomenon. Moreover, while S-PAN nanofiber composites are flexible, they still presents shortcomings, such as low rate capability, which is due to their semiconductor electrical conductivity. In this study, we prepared S-PAN webs with high electrical conductivity via electrospinning using conducting agents. Additionally, we analyzed the electrochemical properties of the S-PAN webs prepared using various conducting agents (acetylene black, Ketjen black, and multi-walled carbon nanotubes). The specific capacity of the S-PAN web prepared using acetylene black was 740 mAh g–1 at the charge rate of 5 C. The excellent rate capability of S-PAN prepared using acetylene black was attributed to its low electrical resistance and low charge transfer resistance.

LiNixCoyAlzO2 (NCA) is one of the most promising candidates of cathode material for lithium ion batteries because of its high capacity, energy density, and low cost. However, Ni-rich NCA cathode materials suffer from side reaction (formation of lithium carbonate and hydrogen fluoride attack) between electrolyte and surface of electrode and irreversible phase transition leading to capacity fading and thermal instability. These problems could be improved by coating and doping of transition metal elements. Si doping contributes to stabilization of the unstable R-3m structure, and Ti coating is capable of prohibiting the direct physical contact of electrode with electrolyte. In this work, LiNi0.8Co0.15Al0.05O2 (NCA) cathode materials coated or/and doped by Ti and Si elements were fabricated by co-precipitation method using the ball-milling. The crystal structure, morphology and electrochemical properties are investigated using X-ray diffraction (XRD), scanning electron microscopy (FE-SEM), transmission electron microscopy (FE-TEM), and WBCS3000 (WonA tech Co., Ltd.). The EIS and charge/discharge results of Si doped and Ti coated NCA exhibited the lowest resistance value (147.19 Ω) and capacity retentions of 88% after 100 cycles at 0.5 C.

A highly ordered mesoporous carbon@iron disulfide (CMK-5@FeS2) composite was prepared via an in-situ impregnation and sulfurization method. The CMK-5 matrix with excellent conductivity and high surface area not only formed a continuous conductive network to improve the performance of the CMK-5@FeS2 composite, but also provided sufficient space to buffer the volume changes during cycling. The CMK-5@FeS2 cell exhibited excellent electrochemical performance. After 80 cycles, the CMK-5@FeS2 cell showed the discharge capacities of 650 and 380 mAh g–1 at 2 C and 5 C, respectively. The excellent results show that CMK-5 with unique mesoporous structure can contribute to accelerating ion transfer in the electrode due to the easy accessibility of the electrolyte, which implies CMK-5@FeS2 composite could be a promising cathode active material for rechargeable lithium ion (Li-ion) batteries.

Li[NixCoyMnz]O2 (LiNCM) is one of the candidate cathode material that can replace the currently commercialized LiCoO2 (LCO) cathode material for lithium-ion batteries (LiBs). The morphological feature having primary particle and secondary sphere particle could affect structural stability, tap density and electrochemical performance of LiNCM. In this work, two LiNCM particles without or with the morphological collapse of the secondary particles were prepared by using a co-precipitation-assisted, solid-phase method and ball milling, and its morphological, structural and electrochemical characteristics were evaluated. The results of XRD, and FESEM demonstrated that the as-prepared two LiNCMs have a typical α-NaFeO2 layered structure and the two morphological features of secondary particles needed in this study. The results of electrochemical properties indicated that the LiNCM electrode without collapsed secondary particles have a good stability in cycle performance compared to that with collapse of secondary particles at 0.5, 1.0 and 2 C-rate. The capacity retention of without and with collapsed NCM was 55.8% and 27.3% after 200 cycles at 1 C-rate, respectively.

Recently, sodium ion batteries have attracted considerable interest for large-scale electric energy storage as an alternative to lithium ion batteries. However, the development of anode materials with long cycle life, high rate, and high reversible capacity is necessary for the advancement of sodium ion batteries. Bi anode is a promising candidate for sodium ion batteries due to its high theoretical capacity (385 mAh g–1 or 3800 mAh l–1) and high electrical conductivity (7.7 × 105 S m –1). Herein, we report the preparation of Bi anode using micro-sized commercial Bi particles. DME-based electrolyte was used, which is well known for its high ionic conductivity. The Bi anode showed excellent rate-capability up to 16 C-rate, and long cycle life stability with a high reversible capacity of 354 mAh g–1 at 16 C-rate for 50 cycles.

To improve the electrochemical properties of Ni-rich LiNi0.8Co0.15Al0.05O2 (LiNCA) cathode material, Ti doped or/and Al(OH)3 coated were by co-precipitation-assisted solid-phase and ball milling method was employed in this work. The morphology, structure, and electrochemical performance of the cathode materials were evaluated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) with energy dispersive X-ray spectrometer (EDS), field emission transmission electron microscopy (FETEM) and electrochemical techniques. Ti doping is introduced into the octahedral lattice space occupied by Li-ions to widen the Li layer spacing and thereby increase the lithium diffusion kinetics. The Al(OH)3 coating also formed a non-uniform layer on the outside of LiNCA, thereby inhibiting side reactions between the electrode and the electrolyte. As a result, the LiNCA electrode showed a high initial discharge capacity of 167.4 mAh/g. However, after 100 cycles, it showed poor cycling stability of 41.7%. In contrast, Ti doped and Al(OH)3 coated LiNCA showed the best cycling stability of 82.2% after 100 cycles.

Sodium vanadium phosphate (NVP) is a potential cathode material for sodium-ion batteries, but its rate capability requires improvement. Herein, the electrode–electrolyte interface is modified using dimethyl ether (DME) electrolyte, such that the porous NVP cathode leads to ultrafast kinetics and ultra-long cycle life in comparison to those observed using conventional ethylene carbonate/propylene carbonate electrolytes. The rate capability and cycle life are the highest reported to date. The Na/NVP half-cell with DME affords good capacity (44 mA h g−1 at 100 A g−1; 854C) and stable ultra-long cycle life for 95 000 cycles with a negligible degradation rate (5.8 × 10−5 % per cycle at 50 A g−1, i.e., 1.05 Na+ reversibly reacts with NVP within 4.5 s). The NVP full cell coupled with a Sn anode delivers a reversible capacity of 70 mA h g−1 at 10 A g−1 for 5000 cycles with 100% coulombic efficiency. After 5000 cycles, the energy density is 217 W h kg−1 and the power density is 30 985 W kg−1 (based on NVP mass). The DME electrolyte effectively modifies the interface for fast kinetics both as a half-cell and a full cell. This simple strategy can be extended to other battery systems to achieve fast kinetics.

Removing decolorizing acid blue 113 (AB113) dye from textile wastewater is challenging due to its high stability and resistance to removal. In this study, we used an artificial neural network (ANN) model to estimate the effect of five different variables on AB113 dye removal in the sonophotocatalytic process. The five variables considered were reaction time (5–25 min), pH (3–11), ZnO dosage (0.2–1.0 g/L), ultrasonic power (100–300 W/L), and persulphate dosage (0.2–3 mmol/L). The most effective model had a 5-7-1 architecture, with an average deviation of 0.44 and R2 of 0.99. A sensitivity analysis was used to analyze the impact of different process variables on removal efficiency and to identify the most effective variable settings for maximum dye removal. Then, an imaginary sonophotocatalytic system was created to measure the quantitative impact of other process parameters on AB113 dye removal. The optimum process parameters for maximum AB 113 removal were identified as 6.2 pH, 25 min reaction time, 300 W/L ultrasonic power, 1.0 g/L ZnO dosage, and 2.54 mmol/L persulfate dosage. The model created was able to identify trends in dye removal and can contribute to future experiments.

Sn/SnO2 nanocomposite of core-shell structure covered with multilayer graphene was synthesized by one step process of electrical wire explosion in liquid media. The synthesized Sn/SnO2 nanocomposites were characterized by various analyzers such as Raman, XRD, FESEM, FETEM, XPS and TGA. The electrochemical performance of the electrode has been investigated by galvanostatic cycling and cyclic voltammetry. FESEM and FETEM results showed that diameter of the Sn/SnO2 nanoparticles is around 10–50 nm and the thickness of the SnO2 shell is about 5–8 nm. The nanocomposite electrode showed a high specific capacity of 1270 mAhg−1 after 100 cycles. Furthermore, the nanocomposite exhibited high reversible capacity of around 650 mAhg−1 at the current density of 5000 mAg−1. These results indicated that multilayer graphene-encapsulated Sn/SnO2 nanocomposites are one of rational structural design to improve the electrochemical performance of Sn-based anode materials for LIBs.

A freestanding porous sulfurized polyacrylonitrile/vapor grown carbon fiber (SVF) composite was prepared as cathode material for high-performance lithium sulfur batteries by a facile electrospinning technique. The synthesized composite possessed high sulfur utilization, high Coulombic efficiency, and excellent cycling stability with the property of flexibility, essential to the development of flexible batteries. The capacity retentions of the SVF cell were 903 mAh g−1 after 150 cycles at 1 C and 600 mAh g−1 after 300 cycles at 2 C. At a high rate of 4 C, the SVF composite showed reasonable capacity retention. The superior performance of SVF composite was attributed to the highly porous structure, which effectively improved the wettability, accessibility, and absorption of electrolyte to facilitate rapid ion transfer in the cell. Vapor-grown carbon fibers embedded inside SVF as a carbon material notably enhanced the electrical conductivity of the cell, guaranteeing the electrochemical performance at high C-rates. The freestanding porous SVF fiber composite is a promising cathode material for advanced flexible lithium sulfur batteries.

Iron sulfide (FeS) has gained reasonable attention as a potential electrode material for lithium-ion batteries owing to its high specific capacity. However, along with the intrinsically low conductivity of FeS, the generation of polysulfide intermediates and volume expansion encountered during the cycling process deteriorates its electrochemical performance. A viable solution would be to design conductive carbon nanoarchitectures capable of effectively accommodating electrochemically active FeS to provide an appropriate conductive pathway which can accelerate ion/electron transport. With this objective, we report a facile, green strategy that facilitates the in situ generation of FeS nanoparticles within graphitic carbon capsules (FeS@GCC) derived from waste biomass. Unlike the complex synthetic procedures reported before, the proposed ecofriendly strategy consists of simpler and fewer processing steps, thereby advocating the versatility of this method as a scalable and economic approach. The FeS@GCC comp...

During the development of sodium ion batteries (SIBs), a long cycle life, high capacity, and high rate are required for the anode materials. In this study, CuS is synthesized by heating S on a Cu current collector at 80 °C for 5 h, which is a simple and scalable process. The CuS exhibits excellent cycle stability of 517 mA h g−1 at 5 A g−1 after 2000 cycles, with 99.2% retention and a coulombic efficiency of almost 100%. CuS also exhibits an ultrahigh rate capability up to 100 A g−1 with a 268 mA h g−1. The CuS electrode is suitable for mass production and displays excellent electrochemical performance; therefore, it is a promising anode for SIBs. Moreover, ex situ scanning electron microscopes are applied to investigate their structural changes. During cycling, the shape of the electrode changes to multiundulating, and then to a flat plate covered with nanometer-sized particles, which can be induced by cracking, pulverization, and agglomeration. Through agglomeration, the CuS recovers from the electric isolation caused by pulverization. This self-healing characteristic could represent a new way of obtaining a long cycle life for anodes with volume changes.

A freestanding γ-Fe2O3/carbon nanofiber composite as the anode of lithium ion batteries has been prepared with γ-Fe2O3 nanoparticles aligned in the tubular channels of the nanofibrous carbon matrix. Innovatively, a large amount of voids are generated for confining a very high active mass content by facilely verifying the ratio of carbon source and the sacrificing pore-forming agent, poly(methyl methacrylate). The best electrochemical performance at an active mass ratio of 70% is obtained with a high discharge capacity of 1088 mAh g−1 retained after 300 cycles at 0.2 C. Good rate capability and long life-span performance are further achieved at 0.5 and 2 C for 600 and 1000 cycles, respectively. In situ X-ray patterns further reveal better exploitation of the active materials for this γ-Fe2O3/carbon nanofiber composite electrode. The enhanced electrochemical performance of lithium ion batteries can be ascribed to the well-dispersed γ-Fe2O3 nanoparticles within the porous carbon matrix, as well as the cross-linked fiber morphology. Consequently, this study provides a superior electrode architecture for constructing flexible anodes of high-performance lithium ion batteries.

Sulfurized polyacrylonitrile (SPAN) is a promising active material for Li/S batteries owing to its high sulfur utilization and long-term cyclability. However, because SPAN electrodes are synthesized using powder, they require large amounts of electrolyte, conducting agents, and binder, which reduces the practical energy density. Herein, to improve the practical energy density, we fabricated bulk-type SPAN disk cathodes from pressed sulfur and polyacrylonitrile powders using a simple heating process. The SPAN disks could be used directly as cathode materials because their π–π structures provide molecular-level electrical connectivity. In addition, the electrodes had interconnected pores, which improved the mobility of Li+ ions by allowing homogeneous adsorption of the electrolyte. The specific capacity of the optimal electrode was very high (517 mA h gelectrode−1). Furthermore, considering the weights of the anode, separator, cathode, and electrolyte, the Li/S cell exhibited a high practical energy density of 250 W h kg−1. The areal capacity was also high (8.5 mA h cm−2) owing to the high SPAN loading of 16.37 mg cm−2. After the introduction of 10 wt% multi-walled carbon nanotubes as a conducting agent, the SPAN disk electrode exhibited excellent cyclability while maintaining a high energy density. This strategy offers a potential candidate for Li/S batteries with high practical energy densities.

The efficiency of heavy metal in biofilm reactors depends on absorption process parameters, and those relationships are complicated. This study explores artificial neural networks (ANNs) feasibility to correlate the biofilm reactor process parameters with absorption efficiency. The heavy metal removal and turbidity were modeled as a function of five process parameters, namely pH, temperature(°C), feed flux(ml/min), substrate flow(ml/min), and hydraulic retention time(h). We developed a standalone ANN software for predicting and analyzing the absorption process in handling industrial wastewater. The model was tested extensively to confirm that the predictions are reasonable in the context of the absorption kinetics principles. The model predictions showed that the temperature and pH values are the most influential parameters affecting absorption efficiency and turbidity.

Usage of cyclic volatile methyl siloxanes (cVMSs) in the industrial process is unavoidable due to their superior properties; however, it is hazardous to human health. Photocatalytic zinc oxide coated aluminum anode is used to degrade the cVMSs in wastewater. In this work, we investigated the relationship among degradation process parameters such as current density (4–20 mA/cm2), initial pH (5–9), plate distance (8–24 cm), UV intensity (0–120 W), and reaction time (30–100 min) vis-a-vis cVMSs removal efficiency by using data-driven artificial neural networks(ANN) model. The ANN model was trained using a backpropagation algorithm with the sigmoid activation function between input, hidden, and the output layers. Two hidden layers with eight neurons in each layer presented the minimum average training error (0.24) and higher (0.99) correlation coefficient values (both Pearson’s r and Adj. R2) as compared with the conventional regression model. The effect and relationship between the parameters and cVMSs removal efficiency were analyzed by single, two variable sensitivity analysis, qualitative and quantitative estimation.

In this paper, the relationship between the pore spatial structures, pore sizes, and pore types of highly ordered mesoporous CMK-based carbons (CMK-1, CMK-3, and CMK-5) and their electrochemical performance in Li-S batteries is investigated. CMK-1 has a complex spatial structure and small pores. The structure is good for limiting polysulfide in the pores, but not for rapid transfer of Li+ ions in the cell. CMK-3 and CMK-5 have similar spatial structures and pore sizes, but different pore types. Compared to the single pore structure of CMK-3, the bimodal pore structure of CMK-5 not only improves the electrolyte accessibility, but also increases the number of reaction sites, resulting in better electrochemical performance. Studying the correlation between the physical structure of carbon-based materials and their electrochemical performance in Li-S batteries will provide new insights for optimizing porous electrode materials.

In this study, NiS/graphene nanocomposites were synthesized by simple heat treatment method of three graphene materials (graphene oxide (GO), reduced graphene oxide (rGO) and nitrogen-doped graphene oxide (N-rGO)) and NiS precursor. The morphology and crystal structure of NiS/graphene nanocomposites were characterized using field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Electrochemical properties were also investigated. NiS/graphene nanocomposites homogeneously wrapped by graphene materials have been successfully manufactured. Among the three nanocomposites, NiS/N-rGO nanocomposite exhibited the highest initial and retention capacity in discharge, respectively, of 1240 mAh/g and 467 mAh/g up to 100 cycles at 0.5 C.

FeS2/C core–shell nanofiber webs were synthesized for the first time by a unique synthesis strategy that couples electrospinning and carbon coating of the nanofibers with sucrose. The design of the one-dimensional core–shell morphology was found to be greatly beneficial for accommodating the volume changes encountered during cycling, to induce shorter lithium ion diffusion pathways in the electrode, and to prevent sulfur dissolution during cycling. A high discharge capacity of 545 mAh g−1 was retained after 500 cycles at 1 C, exhibiting excellent stable cycling performance with 98.8 % capacity retention at the last cycle. High specific capacities of 854 mAh g−1, 518 mAh g−1, and 208 mAh g−1 were obtained at 0.1 C, 1 C, and 10 C rates, respectively, demonstrating the exceptional rate capability of this nanofiber web cathode.

Tin-based materials, due to their high theoretical capacity of 994 mAh g-1 are potential candidates which can substitute the commercialized graphite anodes (372 mAh g-1). However, practical usage of pure tin in Li-ion cells has been hampered by the tremendous volume expansion of more than 260% during the lithium insertion/extraction process, resulting in particle pulverization and electrical disconnection from the current collector. In order to overcome this shortcoming, Sn/Cu6Sn5/C composites in this work were prepared by using pulsed wire explosion in a liquid medium and subsequently in situ polymerization. For comparison, Sn/C composite without tin-copper chemical compounds are also fabricated under a similar process. The Sn/Cu6Sn5/C and Sn/C composites were used as anodes for lithium-ion batteries. The Sn/Cu6Sn5/C composite anode showed good cyclability (scalability) and was maintained up to a capacity of 430 mAh g-1 after 100 cycles at 1 C-rate. The rate capability of the Sn/Cu6Sn5/C composite anode also showed higher performance (280 mAh g-1) than that (200 mAh g-1) of Sn/C composite at the 5 C-rate.

Recently, tin oxide (SnO2) has received significant attention for use as an anode material for next generation lithium-ion batteries (LIBs) owing to its high theoretical capacity (782 mAh g-1), which is more than twice of that of the commercialized graphite (372 mAh g-1). Several additional advantages, such as low cost, environmental friendliness, easy fabrication and natural abundance improve its promise. Although the theoretical capacity of SnO2 is high, volume expansion during cycling causes issue with cycling stability. In this study, an ordered mesoporous SnO2 was synthesized using a hard template (SBA-15), such that its mesoporous structure can buffer SnO2 particles from cracks caused by volume expansion. It can also allow effective electrolyte infiltration to ensure better reactivity of the active material with Li+ ions. The capacity of synthesized mesoporous SnO2 improved to 218.4 mAh g-1 compared regular SnO2 nanoparticles (69.6 mAh g-1) after 50 cycles at a rate of 0.1 C. Furthermore, carbon-coated mesoporous SnO2 enhanced capacity retention upon cycling (844.6 mAh g-1 after 50 cycles at 0.1 C) by insulating and preventing the cracking of the active material during lithiation and delithiation.

Organic cathode materials are of great interest for application in batteries due to their abundant availability and environmental compatibility. An approach to make long chain molecules of these organic materials in order to overcome the problem of dissolution in a liquid electrolyte (LE) and incorporate a highly conducting material to enhance the poor electric conductivity of these materials would be of great research interest. In this work, a novel polyimide (PI)/multiwalled carbon nanotube (MWCNT) nanocomposite is prepared as the cathode material for organic Na-ion batteries (NIBs), via a two-step imidization reaction using perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) and diaminopropane (DAP) to form an insoluble PI. The MWCNT in the composite serves as the conductive channel to maximize the utilization of the active material in the electrode. Furthermore, a three-dimensional fiber network is prepared from an electrospun polyacrylonitrile nanofibrous membrane and used as a gel polymer electrol...

Amorphous phase TiO2 nanotube (NT) arrays as sulfur reservoir are fabricated by anodization method on Ti plate used as current collector. Properties of the NT arrays before heat-treatment are evaluated with those after heat-treatment for applicability as a reservoir and conductor of sulfur electrode. A reasonably high amount of sulfur is loaded (14.8%) from 30% feed sulfur solution at 160 °C in the candidate NT array chosen as the sulfur reservoir. Three electrodes from the only NT array, the sulfur-loaded NT array with and without coating layer are evaluated on electrochemical performances. The sulfur electrode with coating layer, consisting of super-P and PVdF, exhibits the highest initial and retention capacity in discharge, respectively, of 1547 mAh g−1 and 1085 mAh g−1 up to 100 cycles. Rate capability at various C-rates from 0.1 to 30 C is also found to be exceptionally good.

A hierarchically porous carbon nanofiber (HPCNF) material was prepared by a facile electrospinning method, with polyvinylpyrrolidone (PVP) as the carbon source and silica formed in-situ as the template. The carbon nanofibers showed a well-designed pore structure: centered macropores are surrounded by a denser cycle consisting of micro-/mesopores near the surface. Sulfur was encapsulated into the pores by solution penetration, followed by a melt diffusion method to generate a flexible sulfur/HPCNF (S/HPCNF) cloth as the binder-free cathode in lithium sulfur (Li-S) batteries. The HPCNF carbon with multi-scaled pores acts as an efficient host for large amounts of sulfur, and accommodates the associated volume expansion during electrochemical cycling. Moreover, the hierarchical architecture significantly reduces the escape of polysulfides during the cycling. The unique material allowed sulfur loading of 2.2–12.1 mg cm −2 , and exhibited a high sulfur utilization of more than 80% with high areal capacity of 11.3 mAh cm −2 , demonstrating that S/HPCNF is a promising cathode material for Li-S batteries of high energy density.

Pb powder was investigated as an active material as anode for sodium-ion batteries. Precisely, a Pb anode comprising micrometer-sized Pb powder modified with multi-walled carbon nanotubes was fabricated. The anode showed an excellent rate capability, as well as reversible capacities of 370 mAh g−1 at 12.8 C (6208 mA g−1). In addition, the Pb anode exhibited a stable cycle life during 1000 cycles at 10 C with a high reversible capacity of 423 mAh g−1. Using electrochemical tests, scanning electron microscopy, and energy-dispersive X-ray spectroscopy, we revealed the origin of this excellent performance: the micrometer-sized Pb powder undergoes self-healing during cycling, resulting in fiber-like nanometer-sized Pb particles that reinforce the anode structure and provide fast electron transport pathways.

The ideal sulfur supporting material for room-temperature sodium-sulfur (RT-NaS) batteries would concurrently incorporate adsorption capabilities, and high-electrical conductivity, which are essential for improving cycling stability and crucial for enhancing cycling stability and implementation in large-scale applications. In this work, the layered-like structure of TiO2-Ti3C2 Mxene was prepared by a simple hydrothermal method. The prepared TiO2-Ti3C2 material possesses a better optimal structure, which showed the evenly dispersed TiO2 on the Ti3C2 (Ti3C2). The layered-like structure material combines the decrease of volume expansion and the high conductivity of Ti3C2. After being impregnated with sulfur, a significant specific capacity of 255.196 mA h/g was achieved after 1500 cycles at a 1 C-rate with a low-capacity decay. The layered-like structure of TiO2-Ti3C2 prepared by the hydrothermal method is an auspicious cathode material for RT-NaS batteries.

A highly ordered mesoporous sulfurized polyacrylonitrile (MSPAN) composite has been synthesized via in situ polymerization of polyacrylonitrile (PAN) in an SBA-15 template followed by sulfurization. The synthesized composite possessed high sulfur utilization, high Coulombic efficiency, and excellent cycling stability as a cathode active material for high-rate lithium sulfur (Li–S) batteries. A highly ordered mesoporous structure was observed in the MSPAN composite from transmission electron microscopy. Excellent electrochemical and stable cycling performances of the MSPAN composite were obtained, especially at high C rates. The capacity retention of the MSPAN cell was 755 mAh g–1 after 200 cycles at 1 C and 610 mAh g–1 after 900 cycles at 2 C. Even at a higher rate of 5 C, the composite showed reasonable capacity retention. The superior performance of the MSPAN composite was attributed to its highly porous structure, which could effectively improve the wettability, accessibility, and absorption of electro...

Lithium-sulfur (Li-S) batteries are attractive and prominent power sources due to high theoretical capacity and the availability of sulfur at a low price. However, sulfur has limitations such as the formation of polysulfides and low conductivity. To overcome these problems, we prepared a cheese-like carbon (CLC) using a simple annealing process from an egg white. The as-prepared carbon material contains NaCl and KCl compounds. The CLC with nanoholes were formed after cleaning with distilled water and ethanol several times. The prepared CLC had a strong polysulfide capturing ability, high conductivity, a large surface area, and high catalytic activity. To prepare the CLC/S composite, sulfur was added by the melt diffusion method. CLC/S cathode material exhibited a high initial capacity of nearly 1420 mA h g−1 at 0.1 C and excellent rate capability with a low capacity-fading rate. The present work revealed that CLC/S cathodes are potential candidate cathodes for Li-S batteries.

Heavy metal ions in aqueous solutions are taken into account as one of the most harmful environmental issues that ominously affect human health. Pb(II) is a common pollutant among heavy metals found in industrial wastewater, and various methods were developed to remove the Pb(II). The adsorption method was more efficient, cheap, and eco-friendly to remove the Pb(II) from aqueous solutions. The removal efficiency depends on the process parameters (initial concentration, the adsorbent dosage of T-Fe3O4 nanocomposites, residence time, and adsorbent pH). The relationship between the process parameters and output is non-linear and complex. The purpose of the present study is to develop an artificial neural networks (ANN) model to estimate and analyze the relationship between Pb(II) removal and adsorption process parameters. The model was trained with the backpropagation algorithm. The model was validated with the unseen datasets. The correlation coefficient adj.R2 values for total datasets is 0.991. The relationship between the parameters and Pb(II) removal was analyzed by sensitivity analysis and creating a virtual adsorption process. The study determined that the ANN modeling was a reliable tool for predicting and optimizing adsorption process parameters for maximum lead removal from aqueous solutions.

The room temperature sodium-sulfur batteries are an attraction to worldwide industrial and academic as a next-generation energy storage system due to the high energy density, theoretical capacity, and cheap cost of sulfur. However, the practical application is being overdue by fast decay, poor conductivity, and the shuttle effect attributed to the low coulombic efficiency. The present study focuses on preparing MoS2/rGO/S cathode material to overcome the disadvantages of room temperature sodium-sulfur (RT-NaS) batteries. We used hydrothermal method to prepare MoS2, rGO, and MoS2/rGO composite and the sulfur was infused by the melt diffusion. The MoS2/rGO/S composite shows a high reversible capacity of 190 mAh/g after 1000 cycles at a 2 C-rate. The flower-like MoS2/rGO/S composite increases the conductivity and buffers the volume expansion during cycling.

Tin (Sn) based anode materials are the most promising anode materials for lithium-ion batteries due to their high theoretical capacity corresponding to the formation of Li4.4Sn composition (Li4.4Sn, 994 mAh/g). However, the applications of tin based anodes to lithium-ion battery system are generally limited by a large volume change (>260%) during lithiation and delithiation cycle, which causes pulverize and poor cycling stability. In order to overcome this shortcoming, we fabricate a Sn/C nanoparticle with a yolk-shell structure (Sn/void/C) by using pulsed wire evaporation process and oxidation/reduction heat treatment. Sn nanoparticles are encapsulated by a conductive carbon layer with structural buffer that leaves enough room for expansion and contraction during lithium insertion/desertion. We expect that the yolk-shell structure has the ability to accommodate the volume changes of tin and leading to an improved cycle performance. The Sn/Void/C anode with yolk-shell structure shows a high specific capacity of 760 mAh/g after 50 cycles.

We prepared sulfur/active carbon composites via a simple solution-based process using the following commercial activated carbon-based materials: coal, coconut shells, and sawdust. Although elemental sulfur was not detected in any of the sulfur/activated carbon composites based on Thermogravimetric analysis, X-ray diffraction, and Raman spectroscopy, Energy-dispersive X-ray spectroscopy results confirmed its presence in the activated carbon. These results indicate that sulfur was successfully impregnated in the activated carbon and that all of the activated carbons acted as sulfur reservoirs. The sulfur/activated carbon composite cathode using coal exhibited the highest discharge capacity and best rate capability. The first discharge capacity at 1 C (1.672 A g−1) was 1240 mAh g−1, and a large reversible capacity of 567 mAh g−1 was observed at 10 C (16.72 A g−1).

Si film electrodes were fabricated on surface-modified Cu current collectors using an oxidation-reduction process. Flower-like nanostructures (FLNSs) with diameters of 2–3 μm and plate-like nanostructures (PLNSs) with lengths of 1 μm were formed on the Cu foil oxidized at 423 K for 0.5 h, but only the PLNSs remained after sonication. Reduction of the preoxidized Cu foil at 673 K resulted in the formation of plate-like and coral-like nanostructures on the Cu foils reduced for 1 and 3 h and a smooth surface without specific structures on the Cu foil reduced for 6 h. The best electrochemical properties in terms of the first columbic efficiency (85.4%) and the cycle performance (67.3% at 50 cycles) were obtained from the Si film electrode fabricated on the Cu foil that had been reduced for 3 h because the coral-like nanostructures on the Cu foil enhanced the adhesion of the Si film and improved the structural stability of the Si film electrode during the electrochemical reactions.

Si-based electrodes are being designed for use in Lithium-ion batteries with an aim at attaining large energy density and long and stable cycle life. In view of its high theoretical capacity (4200 mAh g −1 ), Si has huge potential as anode material. In this study, we report improvement in the cycling performance of the cell designed with electrode having Si-nanopowder contained in the TiO 2 nanotube array, which is not a composite material. Si-nanopowder is incorporated on the nanotube arrays by three different protocols. The Si-nanopowder electrode prepared by using the facile brushing method, proposed in this study, followed by the surface coating with binder exhibited high cycling behavior. Especially, the cell made with the anode material fabricated by brushing of Si-nanopowder into the TiO 2 nanotube array, having diameter of 150 nm, yield high capacity retention of 1824.9 mAh g −1 up to 300 cycles in the lithiation process at 0.1 C-rate.

A CaO-SiO2 layer was deposited on a pure magnesium substrate that had been prepared by using the spark plasma sintering of atomized powders via a sol-gel process. Various concentrations of tetraethyl orthosilicate (TEOS) were added during the synthesis of the CaO-SiO2 nanocomposites on the pure magnesium substrate; the effects of the TEOS concentration on the corrosion protection and the adhesive properties of the material were investigated. The total thickness of the coating layer ranged from approximately 6 to 10 μm and was affected by the TEOS concentration. Despite the slight surface cracking that occurred on the coating as a result of the strain induced by the annealing process during the deep coating procedure, excellent corrosion and adhesive properties were observed when the TEOS concentration was higher than 15 vol%. When the TEOS concentration was increased to 15 vol%, the corrosion resistance was enhanced, but the adhesive strength was unaffected. Therefore, to produce a CaO-SiO2 coating on pure magnesium for bio-applications, we consider the optimal TEOS concentration to be higher than 15%.

Si, Sn, Al, Ge, and their compounds are some of the potential candidates for use as anodic materials in Li-ion secondary batteries. Especially, Si is a promising anode material for Li-ion batteries due to the high theoretical capacity of 4200 mAh/g-based on the formation of Li4.4Si phase. However, the formation of Li4.4 Si induces a large volume expansion in the electrode and leads to a rapid drop in capacity. To overcome this problem many experiments and theoretical efforts have been focused on enhancing structural stability of an Si in electrode. Several methods have been also reported for the fabrication of three-dimensional electrode arrays. In this study, we report an improvement of the cycling performance of an Si-nanopowder-based electrode. Si-nanopowder was inserted and confined on the C-coated anodic aluminum oxide by using a new method. It is confirmed from this study that cycling behavior of the Si-powder electrode can be significantly improved by using the method proposed in this study.

The structural and electrochemical properties of Si film electrodes with Ni/Ti films on a Cu current collector (Si electrodes) were investigated after annealing in a temperature range of 400–600 °C. Metal-induced crystallization (MIC) and Kirkendall effects were simultaneously observed in the Si electrodes annealed above 450 °C for 2 h. The MIC effect led to the partial formation of strongly -oriented Si in the Si film, and the crystallinity of Si increased with increasing annealing temperature. The Kirkendall effect led to the diffusion of Cu and formed a Cu3Si layer on the surface of the Si film. The capacity of the Si electrodes decreased owing to the formation of the silicide and the efficiency was improved with increasing annealing temperature. A Si electrode annealed at 500 °C for 2 h exhibited good cycle performance with an activation region owing to the anisotropic lithiation during the initial cycles and the Cu3Si layers supporting the Si film.

Sodium-metal chloride batteries have been highlighted as one of the massive energy storage systems for its intrinsically excellent safety and the use of abundant sodium. Nickel and sodium chloride have been the most studied for cathode materials because this chemistry allows high open-circuit voltage and high energy density among the candidates. However, there is a need to reduce the material cost due to costly nickel powders which are used in large quantities for the electrical connection in the cathode. This study proposes an electrochemically activated Na/ZnCl2 battery using less-expensive carbon felt to maintain efficient electron percolation in the cathode and evaluates the charge-discharge behavior and cell impedance. The Na/ZnCl2 cell, which has a capacity of 220 mAh with a new cathode configuration, significantly reduces the charge transfer resistance compared to conventional cells by approximately 42% and 62% at the 10th and 51st cycles, respectively. When the designed capacity increases to 440 mAh with the constant active area of an electrolyte, the reduction of resistance becomes apparent. This enhancement occurs because the carbon felt sufficiently conducts electrons in the cathode compartment and results in a uniform electrode reaction, which is also revealed in our analysis of the microstructure of the electrode.

Sn is one of the promising anode material for lithium-ion and sodium-ion batteries because of Sn has many advantages such as a high theoretical capacity of 994 mAh/g, inexpensive, abundant and nontoxic. However, Sn-based anodes have a critical problem from pulverization of the particles due to large volume change (>300% in lithium-ion battery and 420% in the sodium-ion battery) during alloying/dealloying reaction. To overcome this problem, we fabricate Sn/C particle of core/shell structure. Sn powder was produced by pulsed wire explosion in liquid media, and amorphous carbon coating process was prepared by hydrothermal synthesis. The charge capacity of Sn electrode and amorphous carbon coated Sn electrode was 413 mAh/g and 452 mAh/g after 40 cycles in lithium half-cell test. The charge capacity of Sn electrode and amorphous carbon coated Sn electrode was 240 mAh/g and 487 mAh/g after 40 cycles in sodium half-cell test. Amorphous carbon coating contributed to the improvement of capacity in lithium and sodium battery systems. And the effect of amorphous carbon coating in sodium battery system was superior to that in lithium battery system.

Gel polymer electrolytes (GPEs) were prepared with electrospun poly(vinylidene fluoride-co-hexafluoropropylene) [P(VdF-HFP)] nanofibrous membrane containing low molecular-weight polymer plasticizers, poly(ethylene glycol) dimethyl ether (PEGDME, Mw = 250 and 500). The fibers of electrospun membrane were stacked in layers to give fully interconnected pore structure with high porosity. The porous structure acted as a good host matrix to accommodate the polymer plasticizers. Thermogravimetric analysis (TGA) and field emission scanning electron microscope (FE-SEM) were used for thermal and physical characterizations, respectively. The GPEs exhibit high electrolyte uptake, high ionic conductivity, high anodic stability, and low interfacial resistance. Ionic conductivity and electrolyte uptake increased with the decrease in molecular weight of the polymer plasticizer. Prototype cells using electrospun P(VdF-HFP) nanofibrous GPEs with polymer plasticizers showed stable cyclic performances at different C-rates.

Magnesium doped Li1−2xMgxFePO4/C (x = 0.00, 0.01, 0.03, 0.05) cathode materials were synthesized by sol–gel method, and the effect of magnesium doping as well as its content on the electrochemical properties for lithium batteries was also investigated. Their morphology was studied with field emission scanning electron microscope and Li1−2xMgxFePO4 materials showed the olivine phase without impurities. The thin carbon layer of Li1−2xMgxFePO4/C was confirmed by high resolution transmission electron microscopy. The magnesium doped Li1−2xMgxFePO4/C particles were smaller than those undoped. The Li1−2xMgxFePO4/C materials showed better cycling behavior than undoped LiFePO4, especially at high C-rate in which Li0.94Mg0.03FePO4/C composition exhibited the best electrochemical properties.

Polyaniline (PAN!) was doped with different lithium salts such as LiPFG and LiClO4 and evaluated as cathode-active material for application in room-temperature lithium batteries. The doped PANT was characterized by FTIR and XPS measurements. In the FTIR spectra, the characteristic peaks of PANT are shifted to lower bands as a consequence of doping, and it is more shifted in the case of PANI doped with LiPFG. The cathodes prepared using PANT doped with LiPF6 and LiClO4 delivered initial discharge capacities of 125 mAh g(-1) and 112 mAh g(-1) and stable reversible capacities of 114 mAh g(-1) and 81 mAh g(-1), respectively, after 10 charge-discharge cycles. The cells were also tested using polymer electrolyte, which delivered highest discharge capacities of 142.6 mAh g(-1) and 140 mAh g(-1) and stable reversible capacities of 117 mAh g(-1) and 122 mAh g(-1) for PANT-LiPF6 and PANI-LiClO4, respectively, after 10 cycles. The cathode prepared with LiPFG doped PANT shows better cycling performance and stability as compared to the cathode prepared with LiClO4 doped PANT using both liquid and polymer electrolytes.

Various physical, chemical and mechanical methods, such as inert gas condensation, chemical vapor condensation, sol-gel, pulsed wire evaporation, evaporation technique, and mechanical alloying, have been used to synthesize nanoparticles. Among them, chemical vapor condensation (CVC) has the benefit of its applicability to almost all materials because a wide range of precursors are available for large-scale production with a non-agglomerated state. In this work, Fe nanoparticles and nanowires were synthesized by chemical vapor condensation method using iron pentacarbonyl (Fe(CO)5) as the precursor. The effect of processing parameters on the microstructure, size and morphology of Fe nanoparticles and nanowires were studied. In particular, we investigated close correlation of size and morphology of Fe nanoparticles and nanowires with atomic quantity of inflow precursor into the electric furnace as the quantitative analysis. The atomic quantity was calculated by Boyle's ideal gas law. The Fe nanoparticles and nanowires with various diameter and morphology have successfully been synthesized by the chemical vapor condensation method.