Microporous carbon (MPC) was synthesized from polyvinylidene fluoride (PVDF) using an activation-free approach and used as a selenium host for high-performance lithium-selenium (Li-Se) batteries. The ...microporous carbon/selenium (MPC/Se) composites were applied a cathode in Li-Se batteries with a carbonate-based electrolyte. The influences of PVDF carbonization temperature (600 °C, 700 °C and 800 °C) and Se content (50 wt%, 60 wt%, and 70 wt%) in the cathode were investigated in order to establish correlation between MPC structure and MPC/Se electrochemical performance. The results revealed that the MPC/Se composite cathode, with MPC synthesized at 800 °C and with a Se content of 50 wt%, exhibited a superior reversible capacity of 508.8 mAh g−1 at 0.1C after 100 cycles. Moreover, the MPC/Se maintained a capacity retention of 354.0 mAh g−1 at 0.5C for 200 cycles. The reason for the excellent performance could be attributed to the dominant microporous feature of MPC, which could effectively confine Se and reduce side reactions with electrolytes. Furthermore, increasing Se content from 50 wt% to 70 wt% leaded to decrease in the specific capacity and rate capability of MPC/Se cathode, due to significantly reduced Li-ion diffusion coefficient. This work suggested the effectiveness of MPC derived from commercial PVDF through an activation-free and scalable approach as Se hosts for high-performance Li-Se batteries.
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•One-step activation-free synthesis of microporous carbon (MPC) from PVDF.•MPC/Se showed high excellent performance as cathode in Li-Se batteries.•Properties of MPC/Se depend on pore size and volume, and Se content in MPC/Se.•Micropores and micropore volume are the key merits for porous carbon as the Se host.
Lithium-tellurium (Li-Te) batteries have attracted increasing attention as a next-generation energy storage system due to the appealing electrical conductivity and volumetric capacity. Porous carbon ...hosts are widely used for Te confinement to achieve good electrochemical performance in Li–Te batteries. However, there is a lack of understanding of the effect of carbon pore structure on the performance of Te/C cathodes. Herein, two types of carbons, one with micropores (ASAC25) and the other with mixed micropores and mesopores (ASAC30) are selected as Te hosts to clarify the role of carbon pore structure. Detailed investigations reveal that micropores, rather than mesopores, are critical for effective Te confinement due to complete infiltration of Te in micropores and enhanced Te and C interaction, thus enabling superior stability in ASAC25-Te. The dramatic capacity decline of ASAC30-Te is caused by the dissolution of bulky Te and the loss of active materials in long cycles. ASAC25-Te also achieved exceptional capacity retention of 83.3% after 500 cycles at 1C. Moreover, this work found that the ASAC25 carbon host should be partially filled with Te up to ∼60 wt% to accommodate volume change of Te. The clarification is expected to provide guidance on the further development of high-energy-density Te-based rechargeable batteries.
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•Micropores, rather than mesopores, are critical for effective Te confinement.•ASAC25-Te shows an exceptional capacity retention of 83.3% after 500 cycles at 1C.•Carbon host should be partially filled with Te to buffer volume expansion of Te.
Mesoporous nanocrystalline nickel-alumina promoted catalysts with high surface area were prepared by microemulsion (ME) method and employed in dry reforming of methane reaction. The catalysts were ...characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller surface area analysis (BET), temperature programmed reduction (TPR) and temperature programmed oxidation (TPO) techniques. The results showed that the prepared catalysts had high porosity with great surface area and small crystallite size. Among the K
2
O, MgO, CaO and BaO promoters, the MgO promoter showed considerable effect on catalytic performance and coke suppression of catalyst.
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Nanocrystalline Fe⿿Cr⿿Cu catalysts were evaluated in HTS reaction.Catalysts were prepared by coprecipitation method in water-in-oil microemulsion.The effects of process parameters ...on the catalytic activity were investigated.The prepared catalyst exhibited higher activity than commercial catalyst.The best catalyst showed high stability during 10h in HTS reaction.
In this paper nanocrystalline mesoporous iron-based high temperature water gas shift catalysts were prepared by coprecipitation method in water-in-oil (W/O) microemulsion. The prepared samples were characterized by using X-ray diffraction (XRD), N2 adsorption (BET), temperature-programmed reduction (TPR), Fourier transform infrared spectroscopy (FTIR), transmission and scanning electron microscopies (TEM, SEM) techniques. The results revealed that the Fe2O3 possessed low specific surface area and catalytic activity in high temperature water gas shift reaction. The addition of copper to Fe2O3 favored the active phase formation and significantly decreased the reduction temperature of hematite to magnetite and consequently improved the catalytic activity of Fe2O3. The incorporation of chromium in hematite increased the surface area and catalytic activity of Fe2O3. The results also showed that the prepared Fe⿿Cr⿿Cu catalyst showed higher activity than the commercial catalyst. In addition, the effects of GHSV, steam/gas ratio, and calcination temperature were investigated on the catalytic performance of Fe⿿Cr⿿Cu catalyst.
Lithium-selenium (Li-Se) batteries are a promising energy storage system in electric vehicles due to their high capacity and good kinetics. However, the shuttle effect issue, caused by polyselenide ...dissolution from the Se cathode, has hampered the development of Li-Se batteries. Herein, we developed a facile preparation of porous carbon from a metal-organic framework (MOF) to confine Se (Se/CZIF) and protect the Se/CZIF composite with an alucone coating by molecular layer deposition (MLD). The optimal alucone coated Se/CZIF cathode prepared exhibits a one-step reversible charge/discharge process in the carbonate electrolytes. The inhibition of polyselenide dissolution is credited with the improved electrochemical performance, formation of thin and stable solid electrolyte interphase (SEI) layers, and a reduction in charge transfer resistance, thus improving the overall performance of Li-Se batteries.
Sodium-selenium (Na–Se) batteries are promising energy storage systems due to their relatively low cost and high volumetric energy density of Se cathode. However, the practical application of Na–Se ...batteries has been hindered by the polyselenides dissolution (or shuttle effect phenomena), which could cause low Coulombic efficiency and poor cycling lifetime. Herein, we addressed the polyselenides dissolution by using microporous carbon (MPC) derived from poly (vinylidene fluoride) as the Se host and fluoroethylene carbonate (FEC) as the additive in the electrolyte. The MPC/Se cathode with 3% FEC additive maintained a specific capacity of 382 and 350 mAh g−1 in the 100th and 200th cycle, respectively, while the MPC/Se cathode without FEC could only deliver 317 and 245 mAh g−1 after 100 and 200 cycles, respectively. Another important finding was that the use of FEC additive could prevent the corrosion of Na metal anode from soluble polyselenides, and preserve the structural integrity of Na anode, contributing to the enhanced cycling stability and specific capacity of Na–Se batteries. It is expected that this work could draw researchers’ attention to the importance of reporting and studying Na metal anode while optimizing Se cathode for Na–Se batteries.
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•Microporous carbon derived from poly vinylidene fluoride as the Se host.•The MPC/Se cathode exhibited excellent rate capability and cycle life.•Polyselenide dissolution suppressed by fluoroethylene carbonate (FEC).•Preserve the structural integrity of Na anode by adding FEC.
Lithium-selenium (Li–Se) batteries represent a promising energy storage system due to the relatively high electronic conductivity and high volumetric energy density of Se as a cathode. The design of ...porous carbon with tunable structure and low cost is a key to enabling Se cathodes for high-performance Li–Se batteries. In this study, hierarchically microporous activated carbon (AC) was fabricated from waste coffee grounds through a carbonization and KOH-activation process. Despite the simple synthesis process, the optimized AC (AC-700) had a high surface area of 1355 m2 g−1 and a large microspore volume of 0.52 cm³ g−1. The Se/AC-700 cathode showed a reversible capacity of 655 mAh g−1 after 100 cycles at 0.1C in Li–Se batteries based on a carbonate electrolyte. Moreover, the Se/AC-700 cathode demonstrated excellent cyclic performance over 400 cycles without appreciable capacity decay. The main reason for the good battery performance was attributed to fast electron transfer and Li-ion diffusion in Se confined in the microporous carbon of AC-700. It is expected that this work will shed light on the development of low-cost and stable Se cathodes for high-energy Li–Se batteries.
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•Microporous carbon is synthesized from waste coffee grounds (WCG).•WCG-derived carbon is used as a Se cathode host in Li–Se batteries.•Se/carbon cathode exhibits high a reversible capacity and long cycling life.•Micropores in carbon are key to enabling fast e− transfer and Li+ diffusion in Se.
Selenium (Se) is a promising cathode material for rechargeable lithium batteries due to its prominent volumetric capacity and relatively high electrical conductivity. However, designing a sustainable ...and cost-effective porous carbon as Se host in the cathode with appealing electrochemical performance is a challenge. Herein, a hierarchically porous carbon was synthesized from soybean in a carbonization/activation process and used to develop the selenium cathode material for lithium-selenium (Li-Se) batteries. The effect of activation temperature (500, 600, and 700 °C) on the porous structure of the activated carbons was investigated and correlated to the electrochemical performance of their carbon/selenium (C/Se) cathode composite in Li-Se batteries with a carbonate-based electrolyte. It was revealed that the specific surface area and pore volume of the porous carbon increased with elevating the activation temperature. The Li-Se battery using the carbon activated at 600 °C (C600) showed a superior reversible discharge capacity of 640 mAh g−1 at 0.1 C after 100 cycles, exceptional rate capability, and good long cycling stability of ∼400 mAh g−1 at 1 C over 500 cycles. The superior electrochemical performance of C600/Se cathode compared to the other samples was attributed to its microporous structure coupled with large surface area and pore volume, which could favor effective confinement of Se, electrolyte wetting, Li-ion diffusion, and accommodation of volume change. This work suggests the sustainable development of microporous carbon with a structure suitable for cathode material in Li-Se batteries.
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•Uniform aluminum oxynitride (AlOxNy) developed by atomic layer deposition.•AlOxNy adopted as the surface coating on Si anode for the first time.•Improved capacity retention and ...stability of Si by ultrathin AlOxNy coating (∼2 nm).•AlOxNy as a rigid and ion-conducting artificial solid electrolyte interphase.
Silicon (Si) has received great attention as a promising anode material for lithium-ion batteries (LIBs) due to its high gravimetric capacity and large abundance. However, the use of Si anodes in LIBs has been hindered by their inferior electrochemical performance, resulting from its vast volume expansion and unstable solid electrolyte interphase (SEI). To address these problems, a novel surface coating material, aluminum oxynitride (AlOxNy), was developed using a plasma-enhanced atomic layer deposition technique with trimethylaluminum and plasma N2/H2 as the precursors. The effects of AlOxNy surface coatings on the electrochemical properties of Si electrodes were investigated. With the optimal AlOxNy coating (∼2 nm), the reversible capacity after 140 cycles was improved from 331 mAh g−1 for bare Si electrode to 1297 mAh g−1 for AlOxNy-coated one, and the capacity retention was elevated from 13% to 72%. Post-cycling analysis revealed that the AlOxNy coating significantly suppressed the charge transfer and SEI resistances and maintained the structural integration of Si electrodes by suppressing continuous electrolyte decomposition and electrode delamination from the current collector. This study provides a new perspective on designing advanced functional coating materials for atomic layer deposition for lithium-ion batteries.
Mesoporous nano-crystalline γ-Al
2
O
3
with high surface area prepared by a microemulsion (ME) method was employed as carrier for nickel catalysts in dry reforming of methane for syngas production. ...The structural properties of the catalysts were characterized by X-ray diffraction, Brunauer–Emmett–Teller surface area analysis, temperature programmed reduction and oxidation and scanning electron microscopy techniques. Microemulsion showed it to be a promising way for the production of nano-crystalline aluminum oxide, and the nickel catalysts prepared with this support have significant features and properties to use in the dry reforming reaction. The results revealed that the prepared γ-Al
2
O
3
exhibited a nano-crystalline structure (crystal size: c.4.8 nm) with a high specific surface area (308 m
2
g
−1
). In addition, the catalysts with different nickel contents exhibited high catalytic activity in the dry reforming reaction. The results also showed that an increase in Ni loading from 5 to 15 wt% caused a decrease in the specific surface area and nickel dispersion.
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