Buffer Matrix Research Articles

New chemistry supporting portable solutions for end-stage renal disease dialysis treatment

A new polymeric adsorbent to improve portable dialysis treatment by simplifying urea removal at the dialysate regeneration step is proposed. An adsorbent to remove urea was synthesized by molecular imprinting technology that can potentially overcome drawbacks existing in urease enzyme-based dialysate regeneration technology. Molecularly imprinted polymer (MIP) for urea generates cavities both in shape and in size targeted for urea. Using the synthesized MIP, we have shown removal of urea present in the dialysate buffer. Various experimental conditions such as choice of monomers, porogen, and template to monomer ratios were optimized to achieve highest binding capacity on a column flow through system monitored using high-performance liquid chromatography (HPLC). Taking advantage of the basicity of urea molecule, monomers having Brønsted acidic groups such as acrylic acid, methacrylic acid and itaconic acid were screened. The MIP synthesized using urea:acrylic acid:EGDMA (1:4:12) in acetonitrile:ethylene dichloride (1:1) as porogen gave highest binding capacity of 24.5g/kg of urea in the dialysate buffer matrix.

Enhanced Cycle Stability of Zinc Sulfide Anode for High-Performance Lithium-Ion Storage: Effect of Conductive Hybrid Matrix on Active ZnS.

Zinc sulfide (ZnS) nanocrystallites embedded in a conductive hybrid matrix of titanium carbide and carbon, are successfully fabricated via a facile high-energy ball-milling (HEBM) process. The structural and morphological analyses of the ZnS-TiC-C nanocomposites reveal that ZnS and TiC nanocrystallites are homogeneously distributed in an amorphous carbon matrix. Compared with ZnS-C and ZnS composites, the ZnS-TiC-C nanocomposite exhibits significantly improved electrochemical performance, delivering a highly reversible specific capacity (613 mA h g−1 over 600 cycles at 0.1 A g−1, i.e., ~85% capacity retention), excellent long-term cyclic performance (545 mA h g−1 and 467 mA h g−1 at 0.5 A g−1 and 1 A g−1, respectively, after 600 cycles), and good rate capability at 10 A g−1 (69% capacity retention at 0.1 A g−1). The electrochemical performance is significantly improved, primarily owing to the presence of conductive hybrid matrix of titanium carbide and amorphous carbon in the ZnS-TiC-C nanocomposites. The matrix not only provides high conductivity but also acts as a mechanical buffering matrix preventing huge volume changes during prolonged cycling. The lithiation/delithiation mechanisms of the ZnS-TiC-C electrodes are examined via ex situ X-ray diffraction (XRD) analysis. Furthermore, to investigate the practical application of the ZnS-TiC-C nanocomposite, a coin-type full cell consisting of a ZnS-TiC-C anode and a LiFePO4–graphite cathode is assembled and characterized. The cell exhibits excellent cyclic stability up to 200 cycles and a good rate performance. This study clearly demonstrates that the ZnS-TiC-C nanocomposite can be a promising negative electrode material for the next-generation lithium-ion batteries.

Preparation and electrochemical properties of Sn/C composites

The metal tin (Sn), as one potential anode material for lithium-ion batteries, rapidly degrades its cyclic performance due to huge volume expansion/contraction during lithium intercalation/de-intercalation process. Amorphous carbon was adopted as conductive and buffer matrix to form Sn/C composites. The products were prepared by hydrothermal reaction and carbothermal reduction using tin tetrachloride and glucose as raw materials. The composites were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV) and galvanostatic charge/discharge measurements. The results show that relative smaller metallic tin particles in 1:8 Sn/C composite are formed and distributed more uniformly in the carbon matrix. The lithium intercalation capacity of Sn/C composites reaches 820.4 mAh·g−1, and the capacity retention over 60 cycles remains 54.1%. 1:8 Sn/C composite exhibits enhanced rate performance and cyclic stability compared to 1:5 and 1:10 samples.

Biodegradation kinetics and microbial dynamics of toluene removal in a two-stage cell-biochar-filled biotrickling filter

Abstract The effectiveness of a series-connected biotrickling filter (SC-BTF) system in treating toluene vapors in a waste gas stream was evaluated. The SC-BTF was packed with cell-immobilized biochar beads and seeded mainly with Pseudomonas sp. YATO411 (a toluene degrader). The characteristics of packed beads and operating conditions, kinetics and microbial community of the SC-BTF in the removal of toluene were examined. The adsorption capacity of the cell-biochar beads was 16.03 kg toluene/m3-biochar beads. With a toluene loading of 100 g/m3·h, the first biotrickling filter (BTF1) acted as a buffering matrix that reduced the cell toxicity of toluene to the microorganisms upon adsorbed toluene. The runoff toluene was completely degraded in the second biotrickling filter (BTF2). The maximum reaction rate (Vm) of the cell-biochar bead-packed SC-BTF system (1134 g toluene/m3·d) was 1.6 times that of another that was packed with Raschig rings. Microbial community analysis indicated that the YATO411 originally inoculated in the SC-BTF were the dominant strains under a moderate, starving, or shock loading of toluene.

Analytical Strategies for Quantification of Adeno-Associated Virus Empty Capsids to Support Process Development.

Recombinant adeno-associated virus (rAAV)-mediated gene therapy is a fast-evolving field in the biotechnology industry. One of the major challenges in developing a purification process for AAV gene therapy is establishing an effective yet scalable method to remove empty capsids, or viral vectors lacking the therapeutic gene, from full capsids-viral product containing the therapeutic sequence. Several analytical methods that can quantify the empty-to-full capsid ratio have been reported in the literature. However, as samples can vary widely in viral titer, buffer matrix, and the relative level of empty capsids, understanding the specifications and limitations of different analytical methods is critical to providing appropriate support to facilitate process development. In this study, we developed a novel anion-exchange high-performance liquid chromatography assay to determine the empty-to-full capsid ratio of rAAV samples. The newly developed method demonstrated good comparability with both the transmission electron microscopy and analytical ultracentrifugation methods used in empty-to-full capsid ratio quantification, while providing much higher assay throughput and reducing the minimum sample concentration requirement to 2.7E11 viral genomes/mL.

Boosting High Energy Density Lithium-Ion Storage via the Rational Design of an FeS-Incorporated Sulfurized Polyacrylonitrile Fiber Hybrid Cathode.

In order to satisfy the escalating energy demands, it is inevitable to improve the energy density of current Li-ion batteries. As the development of high-capacity cathode materials is of paramount significance compared to anode materials, here we have designed for the first time a unique synergistic hybrid cathode material with enhanced specific capacity, incorporating cost-effective iron sulfide (FeS) nanoparticles in a sulfurized polyacrylonitrile (SPAN) nanofiber matrix through a rational in situ synthesis strategy. Previous reports on FeS cathodes are scarce and consist of an amorphous carbon matrix to accommodate the volume changes encountered during the cycling process. However, this inactive buffering matrix eventually increases the weight of the cell, reducing the overall energy density. By the rational design of this hybrid composite cathode, we ensure that the presence of covalently bonded sulfur in SPAN guarantees high sulfur utilization, while effectively buffering the volume changes in FeS. Meanwhile, FeS can compensate for the conductivity issues in the SPAN, thereby realizing a synergistically driven dual-active cathode material improving the overall energy density of the composite. Simultaneous in situ generation of FeS nanoparticles within the SPAN fiber matrix was carried out via electrospinning followed by a one-step heating procedure. The developed hybrid cathode material displays enhanced lithium-ion storage, retaining 688.6 mA h g(FeS@SPANcomposite)-1 at the end of 500 cycles at 1 A g-1 even within a narrow voltage range of 1-3.0 V. A high discharge energy density > 900 W h kg(FeS@SPANcomposite)-1, much higher than the theoretical energy density of the commercial LiCoO2 cathode, was also achieved, revealing the promising prospects of this hybrid cathode material for high energy density applications.

Development and Characterization of Monoclonal Antibodies to Botulinum Neurotoxin Type E.

Botulism is a devastating disease caused by botulinum neurotoxins (BoNTs) secreted primarily by Clostridium botulinum. Mouse bioassays without co-inoculation with antibodies are the standard method for the detection of BoNTs, but are not capable of distinguishing between the different serotypes (A–G). Most foodborne intoxications are caused by serotypes BoNT/A and BoNT/B. BoNT/E outbreaks are most often observed in northern coastal regions and are associated with eating contaminated marine animals and other fishery products. Sandwich enzyme-linked immunosorbent assays (ELISAs) were developed for the detection of BoNT/E3. Monoclonal antibodies (mAbs) were generated against BoNT/E3 by immunizing with recombinant peptide fragments of the light and heavy chains of BoNT/E3. In all, 12 mAbs where characterized for binding to both the recombinant peptides and holotoxin, as well as their performance in Western blots and sandwich ELISAs. The most sensitive sandwich assay, using different mAbs for capture and detection, exhibited a limit of detection of 0.2 ng/ml in standard buffer matrix and 10 ng/mL in fish product matrices. By employing two different mAbs for capture and detection, a more standardized sandwich assay was constructed. Development of sensitive and selective mAbs to BoNT/E would help in the initial screening of potential food contamination, speeding diagnosis and reducing use of laboratory animals.

In-situ encapsulation of Ni3S2 nanoparticles into N-doped interconnected carbon networks for efficient lithium storage

Due to the conversion reaction induced high specific capacity, low cost and rich types, the interest on transition metal sulfides for efficient lithium storage has grown. Unfortunately, the intrinsically poor electrical conductivity and structure instability restrict their practical applications. Herein, an in-situ encapsulation strategy is developed to prepare the Ni3S2 nanoparticles encapsulated in interconnected N-doped porous carbon (Ni3S2@NC) through a facile freeze-drying approach and subsequent in-situ conversion. When evaluated as anode material for lithium-ion batteries (LIBs), the as-prepared Ni3S2@NC exhibits a remarkable lithium storage performance, including high reversible capacity (1335.4 mAh g−1 after 100 cycles at 0.1 A g−1), superior rate capability (507.7 mAh g−1 at 4 A g−1) and excellent long-term cycling stability (961.4 mAh g−1 after 600 cycles at 0.5 A g−1 and 862.8 mAh g−1 after 600 cycles at 1 A g−1), displaying one of the best lithium storage performances among the Ni3S2-based electrodes reported by now. Such an excellent lithium storage performance should be attributed to the unique structure advantages of Ni3S2@NC inherited from the in-situ encapsulation strategy, such as tight combination, increased electrical conductivity, shortened ion diffusion distance and buffering matrix provided by N-doped porous carbon networks. Importantly, the facile design and engineering strategy should also be applied to explore other nanoarchitectures to boost their lithium storage performances.

Electrochemical performance of porous CaFe2O4 as a promising anode material for lithium-ion batteries

Abstract The performance of existing lithium-ion batteries (LIBs) is greatly hindered by the low specific capacity of graphite-based anodes (372 mAh g−1). Therefore, development of suitable anode materials that exhibit higher and stable capacity is necessary to improve performance. Transition metal oxides have attracted tremendous attention as next-generation anode materials for LIBs due to their high theoretical capacity. Herein, we report the synthesis of a porous CaFe2O4 by a facile and time efficient solution combustion synthesis technique for use in an anode for LIBs. The as-prepared material exhibited improved electrochemical performance with specific discharge capacities of 441 mAh g−1, 518 mAh g−1, and 516 mAh g−1 for the initial three cycles. It achieved stability with a deliverable specific discharge capacity of 551 mAh g−1 after 150 cycles at a current density of 200 mA g−1. The porous CaFe2O4 exhibits improved cyclic performance and rate capability. These improvements are attributed to the porous nature of active material and, more importantly, the presence of CaO, which effectively alleviates the volume changes by acting as a buffer matrix.

Na2SnO3 as a novel anode for high performance lithium storage and its electrochemical reaction mechanism

Herein, Na2SnO3 is employed as an anode for rechargeable lithium ion battery (LIB). We thoroughly investigated the electrochemical performance of Na2SnO3 in comparison with the most commonly used Sn based oxides, such as SnO2 and Li2SnO3. It is found that Na2SnO3 is greatly superior to SnO2 and Li2SnO3 in terms of capacity, cycling stability and rate capability. Impressively, Na2SnO3 presents favorable specific capacity of 480 mA h g−1 at current density of 200 mA g−1 after 100 cycles and still delivers a capacity of 439 mA h g−1 at extremely large current density of 1000 mA g−1, which are leading the performance in anodes for LIBs. Ex situ SEM analysis of anodes after different cycles revealed the surface microstructure of anodes plays a critical role in determining cycling stability. The SEM results show big cracks on the surface of electrode for SnO2 after less 15 cycles and for Li2SnO3 after more 100 cycles, resulting from their severe volume change during charging-discharging process. However, Na2SnO3 electrode exhibits uniform surface morphology after 100 cycles. It is concluded the “Na2O″ intrinsic matrix of Na2SnO3 combining with “Li2O″ formed from the conversion reaction can act as a mixture buffering matrix that contributes to keeping the electrochemically formed nanoscale Sn particles apart and preventing their agglomeration during Li−Sn alloy formation and decomposition, thus inhibiting the volume expansion and the capacity fading by maintaining the electrode integrity. In addition, the electrochemical reaction mechanism of Na2SnO3 with Li is investigated by ex situ XRD technique. The findings in this study provide a new valuable anode for high-performance LIBs and an insightful viewpoint of developing anode materials with high electrochemical performance by introducing the electrochemical inactive intrinsic matrix.

Dandelion-like Mesoporous SiOx@C Nanoparticles for High-Capacity and Ultralong Lifespan Lithium-Ion Battery Anode

Silicon suboxide (SiOx, 0˂x˂2) is one of the promising anode materials for lithium-ion batteries (LIBs) due to its high specific capacity, low operating voltage (˂0.4 V) and rich natural resource [1]. SiOx converts to Si nanoparticles and inert components (lithium oxide and lithium silicate) during initial lithiation process, where the Si nanoparticles can reversibly store lithium ions and the inert components act as buffer matrix to accommodate the large volume variation of nano-sized Si. Compared to pure Si, SiOx electrode shows relatively good cycling stability while maintaining high specific capacity, thus is a promising anode material for high energy density Li-ion batteries. Nevertheless, bulk SiOx electrode cannot withstand long-term cycling due to the inevitable volume variation upon lithium uptake and removal. In addition, the poor intrinsic electrical conductivity of SiOx often limits the capacity utilization [2]. In this work, we prepared mesoporous SiOx@C nanoparticles with unique “dandelion flower” structure by a facile microemulsion method combined with a subsequent carbon coating process. The SiOx particles display a dandelion flower like porous structure with large void space and specific surface area. A uniform carbon layer wholly encapsulates the SiOx backbone, forming a 3D mono-dispersed SiOx@C particle with particle size of ~70 nm. The abundant mesopores inside particle can accommodate the volume expansion of SiOx during lithiation and lower the diffusion-induced stresses, which prevent from the electrode pulverization and thus maintain the structural integrity of SiOx@C electrode during repeated cycles. The 3D carbon network not only effectively facilitates the fast electron transport throughout the whole SiOx particle and thereby improving the electrode reaction kinetics, but also homogenizes the local current density of active particles and hence decreases the mechanical stress induced by volume change of SiOx. Benefiting from these advantages, the prepared SiOx@C anode exhibits ultrahigh reversible capacity (1261 mAh g-1 at 0.1 A g-1), ultralong lifespan (635 mAh g-1 at 2 A g-1 after 1000 cycles with retention of 88.6%), as well as superior rate capability (293 mAh g-1 at 10 A g-1). [1] Journal of Power Sources, 2017, 363: 126-144. [2] J. Mater. Chem. A, 2014, 2, 3521-3527.

In situ growth of sandwich-like NiMoO4 nanowires/reduced graphene oxide hybrid for high-performance lithium storage

Transition metal oxide electrodes, with rational structure as well as component design and combination with carbonaceous conductive support, are widely used in high-performance lithium-ion batteries (LIBs). Herein, NiMoO4 nanowires in situ decorated on reduced graphene oxide (NiMoO4/rGO) were synthesized through a facile hydrothermal and subsequent annealing method. Due to the enhanced electrical conductivity and buffering matrix provided by rGO and the synergistic effect between NiMoO4 and rGO, the resultant NiMoO4/rGO exhibits short ion transport pathways and improved diffusion kinetics. The results reveal that NiMoO4/rGO hybrid shows much improved lithium storage performances compared with pure NiMoO4 nanowires including a high specific capacity (1212.4 mAh g−1 after 100 cycles at 0.2 A g−1), high rate capability (988.6 mAh g−1 at 2 A g−1 and 928.1 mAh g−1 at 4 A g−1) and excellent cycling performance at high current density (1007.6 mAh g−1 after 1000 cycles at 1 A g−1) when applied as anode material for LIBs, outperforming most of the reported metal molybdates-based electrodes. Besides, such excellent lithium storage performance, combined with the simple hydrothermal-annealing synthesis strategy, makes the NiMoO4/rGO a promising anode material for high-performance LIBs.

A three-dimensional highly conductive structure of Si/NiSi2 anode for Li-ion battery

The low conductivity, structural degradation during cycling and severe capacity loss in the initial cycle make silicon difficult to meet the increasing demand in various aspects as one of the promising anodes material. Here we introduce a conductive three-dimensional structure to tackle these problems. The design of the electrode is achieved via plasma enhanced chemical vapor deposition (PECVD) of silicon nanoparticles onto three-dimensional nickel foam, forming a 3D conductive network. The three-dimensional networks provide abundant electrochemical activity sites and conductive transport paths. Besides, this design can significantly improve the energy density of the electrode since no binders or conductive agents are deposited. The initial columbic efficiency of Si anode is greatly improved by tuning the deposition time. A secondary phase of NiSi2 is found from XPS results which serves as an inactive buffer matrix in the composite. The anode with 40min deposition time achieves remarkable electrochemical performance as 84.84% initial columbic efficiency and 525.5mAh·g−1 specific capacity after the 100th cycles. This preferable performance is the result of enhanced physical and mechanical properties of the electrode with a 3D conductive structure.

Single‐Phase Cu3SnS4 Nanoparticles for Robust High Capacity Lithium‐Ion Battery Anodes

AbstractWith the evolution of Li‐ion batteries, they have been employed in many applications. However, high energy density and power density batteries are yet to be developed to meet the necessities at the application end. Sulfides are a good choice as anode material as they show a much higher specific capacity than conventional graphite anodes. But unfortunately, sulfide dissolution and polysulfide shuttling are big drawbacks for their operation. Herein, single phase ternary metal sulfide Cu3SnS4 (CTS) nanoparticles are synthesized with high Cu : Sn ratio and examined for application as Li‐ion battery anode. High specific capacities of 1082 mAh g−1 at 0.2 A g−1 and 440 mAh g−1 at a high rate of 3 A g−1 are realized with superior stability tested up to 950 cycles. Utilizing the CTS NPs can minimize the polysulfide dissolution. The high Cu : Sn ratio provides excess Cu atoms as the buffer matrix for volume expansion of Sn, leading to high stability and specific capacity. Compared to other reported Cu based mixed phase or composite ternary sulfide materials, the CTS NPs presented herein show a better performance. In a full cell device using LiCoO2 (LCO) as cathode, a good performance is achieved as well with an energy density of 405 Wh/Kg at 0.1 A g−1.

Application of Sn-Ni Alloy as an Anode for Lithium-Ion Capacitors with Improved Volumetric Energy and Power Density

Lithium-ion capacitors (LIC) constructed by combining a supercapacitor-like cathode and battery-like anode are expected to bridge a gap between low power density from lithium-ion batteries (LIB) and low energy density from the supercapacitors. In this study, we synthesize the Sn-Ni alloy by electrodeposition in the aqueous solution as an anode for LIC. The lower volume expansion rate of Sn-86 than pure Sn anode can be confirmed by in-operando investigation using an optically transparent cell during the 1st charging process. This is attribute to the co-deposited Ni can act as a buffer matrix to restrain volume expansion. For the full-cell test, the pre-lithiation condition of Sn-Ni was investigated with different depth of discharge levels. As a result, a LIC consisting of activated carbon (AC) cathode and Sn-86 exhibits a good cyclability for 3000 cycles with a capacity retention of 80% and coulombic efficiency of 98% at 3000th cycle. The Sn-Ni//AC LIC shows improved volumetric energy and power density than graphite//AC LIC. This study presents a new possibility of Sn-Ni alloy as an anode for the improved electrochemical performance of LIC.

Invasive alien plant species, fragmentation and scale effects on urban forest community composition in Durban, South Africa

BackgroundUrban forests are under increased pressure from invasion by exotic (alien) species. The vegetation present in the matrix of urban sites is a rich source of alien invasive propagules, which increases the risk of alien invasion in forests within an urban space, leading to a decline in indigenous species. Therefore, determining the distribution patterns of native and exotic species as influenced by environmental factors can assist in quantifying the impact of exotic species at broad scales based on responses on a finer scale. Quantifying the effects of multiple environmental factors on the distribution patterns of both indigenous and alien species in the ecosystem may help in prescribing suitable management efforts.MethodsFifteen forest patches were sampled in the eThekwini (Durban) Municipality and data collected from 74 100-m2 plots with different degrees of invasion. Indigenous and alien species of trees, shrubs and climbers occurring in ten and more plots were considered for analysis and the CANOCO 5.1 package was used to run various constrained ordination analyses. Variation partitioning analysis was used to assess the impact of environmental variables at different spatial scales, namely the plot and patch scales.ResultsCanopy gaps are the major controlling factor for invasive alien plants (IAPs) occurrence at fine scale. At patch level, residential and industry areas outside the boundaries (buffer area) of forest patches have a high influence on the distribution of IAPs. Communities dominated by the invasive Chromolaena odorata (L.) R.M. King are most common on the lowland coastal forests while communities dominated by either Litsea glutinosa (Lour.) C.B.Rob. or Cardiospermum grandiflorum Sw. can prevail in both lowland coastal and scarp forests.ConclusionsCanopy gaps in lowland forests can facilitate the transition of native forests to novel communities containing a variety of alien plant species. Communities of shrub, climber and tree IAPs occur in lowland coastal forests while climber and tree IAPs dominate the high-elevation scarp forests. The resilience shown by some native species to the tree, shrub and climber IAPs by remaining when IAPs establish makes these species very suitable for restoration projects. Forest patches surrounded by a high incidence of residential and industrial areas in the buffer matrix are likely to have a high diversity of IAPs. Larger patch size and high connectivity to nearby native forests are key in reducing invasion by IAPs.

Hierarchical Sb2MoO6 microspheres for high-performance sodium-ion battery anode

Antimony (Sb)-based materials have been extensively studied as anodes for sodium-ion batteries (SIBs) because of the high theoretical capacity of Sb (660 mA h/g). However, the poor electrochemical behaviors caused by the severe volume expansion of Sb during the sodiation/desodiation process constrains its practical applications. Herein we report a facile microwave-assisted hydrothermal method for the synthesis of hierarchical Sb2MoO6 microspheres assembled by one-dimensional nanobelts without the use of any surfactants. When used as an anode material for SIBs, it delivers large reversible capacities of 637.3 and 498.7 mA h/g at current densities of 200 and 1000 mA/g after 100 cycles, respectively, exceptional rate capability with 428.1 mA h/g retained at 5 A/g and long cycle life (460.6 mA h/g with capacity retention of 98.7% after 450 cycles at 2 A/g). Moreover, a sodium-ion full cell with Sb2MoO6 anode was assembled, presenting a large capacity and stable cyclability with a high output voltage. Based on extensive experimental analyses and first-principles calculations, we find that such superior electrochemical performances can be attributed to its distinctive capability of forming a self-constructing conductive Na-Mo-O buffer matrix during discharge/charge process, which not only efficiently buffers the volume expansion of the Na-Sb alloying/dealloying, but also provides good electronic conductivity to facilitate electron transfer. Notably, the novel hierarchical Sb2MoO6 microsphere anode exhibits excellent electrochemical performances without hybridizing with any special carbonaceous materials. Such high-performance novel anode material together with the new findings in electrochemical mechanism in this work may open a way for the design of future energy storage devices.

Functionalized Charcoal as a Buffering Matrix of Copper and Zinc Availability

ABSTRACT: High copper (Cu) and zinc (Zn) contents in soil can cause phytotoxicity to plants and contaminate surface and groundwater, with negative effects on agriculture and the environment. Functionalized charcoal (OCh) has high cation exchange capacity (CEC) and the ability to adsorb Cu and Zn and control their availability in the soil and water. An adsorption study at two pH levels was carried out to evaluate increasing Cu and Zn sorption capacity provided by the functionalization process of a charcoal. [...]

Constructing Three-Dimensional Porous Carbon Framework Embedded with FeSe2 Nanoparticles as an Anode Material for Rechargeable Batteries.

Metal selenides have caused widespread concern due to their high theoretical capacities and appropriate working potential; however, they suffer from large volume variation during cycling and low electrical conductivity, which limit their practical applications. In this article, a three-dimensional (3D) porous carbon framework embedded with homogeneous FeSe2 nanoparticles (3D porous FeSe2/C composite) was synthesized by a facile calcined approach, following a selenized method without a template. As the uniformity of FeSe2 nanoparticles and 3D porous structure are beneficial to accommodate volume stress upon cycling and shorten electrons/ions transport path, associated with carbon as a buffer matrix for increasing conductivity, the 3D porous FeSe2/C composite displays excellent electrochemical properties with high reversible capacities of 798.4 and 455.0 mA h g-1 for lithium-ion batteries and sodium-ion batteries, respectively, when the current density is 100 mA g-1 after 100 cycles. In addition, the as-prepared composite exhibits good cycling stability as compared to bare FeSe2 nanoparticles. Therefore, the facile synthetic strategy in the current work provides a new perspective in constructing a high-performance anode.

SnO2 Nanosheets Anchored on a 3D, Bicontinuous Electron and Ion Transport Carbon Network for High-Performance Sodium-Ion Batteries.

Here, we demonstrate the in situ growth of SnO2 nanosheets on a freestanding carbonized eggshell membrane (CEM), which provides three-dimensional, bicontinuous electron and ion transport pathways through a massively interconnected carbon fiber skeleton and interpenetrated pore network, respectively. This CEM has other advantages such as the ability to alleviate mechanical stress during cycling as a buffer matrix. When used as an additive-free anode in a sodium-ion battery, SnO2 nanosheets can realize a complete electrochemical reaction and maintain good cycling stability with the help of a CEM. For instance, SnO2 nanosheets delivered a high reversible capacity of 656 mA h g-1 in the 5th cycle at 0.1 A g-1, approaching 98% of its theoretical specific capacity, and maintained a high reversible specific capacity of 420 mA h g-1 after 200 cycles at 0.2 A g-1.