Uniformly dispersing Sb2Se3 nanoparticles in porous carbon as an anode material for enhancing sodium storage capacity

About 60 nm Sb2Se3 nanoparticles are uniformly embedded in a porous carbon substrate to prepare a Sb2Se3/C composite through a combination of pyrolysis reduction and solid-phase selenization. The Sb2Se3/C anode exhibits excellent sodium storage capacity. The initial discharge capacity is up to 420 mA h g-1 at 0.1 A g-1, and the specific capacity still remains 339 mA h g-1 after 1000 cycles, with a high capacity retention rate of 80%.

Sb nanoparticles embedded uniformly on the surface of porous carbon fibres for high-efficiency sodium storage

Sb nanoparticles (∼50 nm) are embedded uniformly on the surface of carbon fibers (Sb NPs-SCFs) without scattered Sb NPs. The Sb NPs-CNFs anode exhibits excellent sodium storage, delivering a second cycle discharge capacity of 455.7 mA h g-1 at 1.0 A g-1 and a stable capacity of 381.9 mA h g-1 after 200 cycles, achieving a notable retention of 83.8%.

Coordination Regulation Strategy in Fabricating Bi2S3@CNFs Composites with Uniform Dispersion for Robust Sodium Storage

To solve large volume change and low conductivity of Bi2S3-based anodes, a coordination regulation strategy is proposed to prepare Bi2S3 nanoparticles dispersed in carbon fiber (Bi2S3@CNF) composites. It has been discovered that introducing trimesic acid as a ligand can significantly improve the loading and dispersion of Bi3+ in polyacrylonitrile fibers. The results exhibit that Bi2S3 nanoparticles of 200-300 nm are uniformly anchored on the superficial surface layer of CNFs, and Bi2S3 nanoparticles of about 20 nm are evenly dispersed in the interior of CNFs. Assessed as sodium-ion batteries' anode material, the discharge capacity of the Bi2S3@CNF anode in the second cycle is 669.3 mAh g-1 at 0.1 A g-1 and still retains 620.2 mAh g-1 after 100 cycles, with the capacity retention rate of 92.7%. Even at 0.5 A g-1, the specific capacity of the second cycle is 432.99 mAh g-1, which still keeps 400.9 mAh g-1 after 800 cycles, with a retention rate of 92.5%. The excellent cycle stability is mainly attributed to the uniform distribution of small Bi2S3 nanoparticles in CNFs providing abundant active sites, preventing side reactions, relieving volume expansion, improving the electrical conductivity, and accelerating the electrochemical reaction kinetics.

Statistics design for the synthesis optimization of lignin-sulfonate sulfur-doped mesoporous carbon materials: promising candidates as adsorbents and supercapacitors materials

This study employed lignin-sulfonated (LS) to develop biobased carbon materials (LS-Cs) through a sulfur-doping approach to enhance their physicochemical properties, adsorption capabilities, and energy storage potentials. Various characterization techniques, including BET surface area analysis, SEM imaging, XPS, Raman spectroscopy, and elemental composition (CHNS), were employed to assess the quality of the LS-Cs adsorbent and electrode samples. Response Surface Methodology (RSM) was utilized for optimizing the two main properties (specific surface area, ABET, and mesopore area, AMESO) by evaluating three independent factors (i.e., activation temperature, ZnCl2:LS ratio, and sulfur content). According to the statistical analysis, ABET and AMESO were affected by ZnCl2 and sulfur content, while the pyrolysis temperature did not affect the responses in the studied conditions. It was found that increasing the ZnCl2 and sulfur contents led to an increment of the ABET and AMESO values. The LS-C materials exhibited very high ABETvalues up to 1993 m2 g-1 and with predominantly mesoporous features. The S-doping resulted in LS-Cs with high sulfur contents in their microstructures up to 15% (wt%). The LS-C materials were tested as adsorbents for sodium diclofenac (DCF) adsorption and reactive orange 16 dye (RO-16) and as electrodes for supercapacitors. The LS-Cs exhibited excellent adsorption capacity values for both molecules (197-372 mg g-1) for DCF, and (223-466 mg g-1) for RO-16. When tested as electrodes for supercapacitors, notably, LS-C3, which is a doped sample with sulfur, exhibited the best electrochemical performance, e.g. high specific capacitance (156 F/g at 50 mV/s), and delivered an excellent capacitance after 1000 cycles (63 F/g at 1 A/g), which denotes the noteworthy capacitive behavior of the S-doped electrode. Thus, the present work suggests an eco-friendly resource for developing effective, productive carbon materials for adsorbent and electrodes for SC application. However, further studies on the complete application of these materials as adsorbents and electrodes are needed for a deeper understanding of their behavior in environmental and energy storage applications.

A High-Performance, Low Defected, and Binder-Free Graphene-Based Supercapacitor Obtained via Synergistic Electrochemical Exfoliation and Electrophoretic Deposition Process

An integrated electrochemical exfoliation and electrophoretic deposition (EPD) method is developed to achieve a high-performance graphene supercapacitor. The electrochemical delamination of graphite sheet has obtained a low-defected few-layer graphene adorned with oxygen-containing functional groups. Then, the EPD process produced a binder-free electrode to alleviate the graphene restacking problem. The electrode prepared using a deposition voltage of 5 V exhibits the highest specific capacitance of 145.95 F/g at 0.5 A/g from three-electrode measurement. Moreover, this EPD-prepared electrode also demonstrates superior electrochemical properties compared to electrodes fabricated using PVDF binder. In the real symmetrical cell, the EPD-prepared electrode also shows excellent performance with a high rate capability of 82.31 % (from 0.5 A/g to 10 A/g), high cycling stability of 95.00 % (at 5 A/g) after 10,000 cycles, and rapid frequency response with short relaxation time (τ 0 ${{\tau }_{0}}$ ) of 9.73 ms. These results indicate that this integration method is beneficial to construct a high performance binder-free supercapacitor electrode consisting of low-defected graphene materials, low electrode resistance, and less agglomeration of graphene sheets by utilizing an environmentally friendly process.

N-doped 3D carbon encapsulating nickel selenide nanoarchitecture with cation defect engineering: An ultrafast and long-life anode for sodium-ion batteries

Transition metal chalcogenides (TMCs) hold great potential for sodium-ion batteries (SIBs) owing to their multielectron conversion reactions, yet face challenges of poor intrinsic conductivity, sluggish diffusion kinetics, severe phase transitions, and structural collapse during cycling. Herein, a self-templating strategy is proposed for the synthesis of a class of metal cobalt-doped NiSe nanoparticles confined within three-dimensional (3D) N-doped macroporous carbon matrix nanohybrids (Co-NiSe/NMC). The cation defect engineering within the developed Co-NiSe and 3D N-doped carbon plays a crucial role in enhancing intrinsic conductivity, reinforcing structural stability, and reducing the barrier to sodium ion diffusion, which are verified by a series of electrochemical kinetic analyses and density functional theory calculations. Significantly, such cation defect engineering not only reduces overpotential but also accelerates conversion reaction kinetics, ensuring both exceptional high-rate capability and extended durability. Consequently, the optimally engineered Co-NiSe/NMC demonstrates a remarkable rate performance, delivering 390 mAh g-1 at 10 A g-1. Moreover, it exhibits an unprecedented lifespan, maintaining a remarkable capacity of 403 mAh g-1 after 1400 cycles and 318 mAh g-1 after 4000 cycles, even at high rates of 1.0 and 2.0 A g-1, respectively. This work marks a substantial advancement in achieving both high performance and prolonged cycle life in sodium-ion batteries.

Effect of Sulfur Modification on Structural and Electrochemical Performance of Pitch-Based Carbon Materials for Lithium/Sodium Ion Batteries

Coal tar pitch (CTP) has become an ideal choice in the preparation of anode precursors for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) because of its abundant carbon content, competitive pricing and adjustable structure properties. In this paper, sulfurized pitch-based carbon (SPC-800) was obtained by allowing CTP to react with sulfur at 350 °C and subsequently achieve carbonization at 800 °C. SPC-800 was more disordered and had a larger layer spacing than carbonized CTP (PC-800). Upon utilization as an anode for LIBs, SPC-800 possessed a higher reversible specific capacity (478.1 mAh g-1 at 0.1 A g-1), while utilization in SIBs displayed a capacity of 220.9 mAh g-1 at 20 mA g-1. This work is an important guide to the design of high-performance anodes suitable for use with both LIBs and SIBs.

Sn0.1-Li4Ti5O12/C as a promising cathode material with a large capacity and high rate performance for Mg-Li hybrid batteries

The development prospects of conventional Li-ion batteries are limited by the paucity of Li resources. Mg-Li hybrid batteries (MLIBs) combine the advantages of Li-ion batteries and magnesium batteries. Li+ can migrate rapidly in the cathode materials, and the Mg anode has the advantage of being dendrite-free. In this study, a type of Li4Ti5O12 composite material doped with Sn4+ and a conductive carbon skeleton (Li4Ti4.9Sn0.1O12/C, Sn0.1-LTO/C) was prepared by a simple one-pot sol-gel method. The doped Sn4+ replaces part of Ti4+ in the crystal lattice, which makes Ti3+ require charge compensation, thus improving the ionic conductivity. The intervention of the conductive carbon skeleton further improves the conductivity of the Sn0.1-LTO/C composite material. The performance of Sn0.1-LTO/C as the cathode of MLIBs is explored. The initial discharge capacity was 159.1 mA h g-1 at 0.5 C, and it was maintained at 105 mA h g-1 even after 500 cycles. The excellent electrochemical performance is attributed to a small amount of Sn doping and the involvement of the conductive carbon skeleton, which indicated that the Sn0.1-LTO/C composite material provides great potential application in MLIBs.

Etching-induced ion exchange engineering of two-dimensional layered NiFeCo-based hydroxides for high energy charge storage

Efficient and rapid synthesis of transition metal-based hydroxides with tailored microstructures has emerged as a promising approach to fabricate high-performance electrode materials for energy storage devices. However, many conventional synthesis methods are cumbersome, expensive and time-consuming, and the microstructures of electrode materials are usually uncontrollable. Herein, we propose a fast and cost-effective approach to electrochemically in situ grow NiFeCo-based ternary hydroxides (NiFeCo-THs) with layered nanosheet structures on pretreated nickel foam (NF). The in situ grown NiFeCo-THs were in direct contact with the NF to form a monolithic electrode as NiFeCo/NF. By engineering the ion exchange process for controlling the ionic ratio, the monolithic Ni1(Fe/Co = 1/1)0.5/NF electrode was fabricated and found to show the optimum electrochemical behavior with a specific capacitance of 2.32 C cm-2 at 2 mA cm-2 as a result of its characteristic microstructures. Furthermore, a hybrid supercapacitor was constructed utilizing the monolithic Ni1(Fe/Co = 1/1)0.5/NF electrode and activated carbon as the cathode and anode, respectively, and it was found to have an energy density of 81.1 μW h cm-2 at a power density of 808.8 μW cm-2. After 5000 cycles, 84.0% of the initial capacitance of the hybrid supercapacitor was maintained, and the monolithic Ni1(Fe/Co = 1/1)0.5/NF electrode still retained the arrayed nanosheet structure.

In-situ electrodeposited Co0.85Se@Ni3S2 heterojunction with enhanced performance for supercapacitors

Rational design of porous heterostructured electrode materials for high-performance supercapacitors remains a big challenge. Herein, we report the in situ synthesis of Co0.85Se@Ni3S2 hybrid nanosheet arrays supported on carbon cloth (CC) substrate though an efficient two-step electrodeposition method. Compared with pure Co0.85Se and Ni3S2, the well-defined Co0.85Se@Ni3S2 heterojunction possesses enriched active sites, improved electrical conductivity, and reduced ion diffusion resistance. Benefiting from its hierarchically porous nanostructure and the synergistic effect of Co0.85Se and Ni3S2, the as-synthesized Co0.85Se@Ni3S2 electrode delivers a gravimetric capacitance (Cg)/volumetric capacitance (Cv) of 1644.1F g-1/3161.7F cm-3 at 1 A g-1, outstanding rate capability of 60.7% capacitance retention at 20 A g-1, as well as good cycling performance of 87.8% capacitance retention after 5000 cycles. Additionally, a hybrid supercapacitor (HSC) device presents a maximum energy density (E) of 65.7 Wh kg-1 at 696.2 W kg-1 with 93.3% cyclic durability after 15,000 cycles. Thus, this work proposes a simple and effective strategy to fabricate porous heterojunctions as high-performance electrode materials for energy storage devices.

Integration of Multiple Heterointerfaces in a Hierarchical 0D@2D@1D Structure for Lightweight, Flexible, and Hydrophobic Multifunctional Electromagnetic Protective Fabrics

The development of wearable multifunctional electromagnetic protective fabrics with multifunctional, low cost, and high efficiency remains a challenge. Here, inspired by the unique flower branch shape of "Thunberg's meadowsweet" in nature, a nanofibrous composite membrane with hierarchical structure was constructed. Integrating sophisticated 0D@2D@1D hierarchical structures with multiple heterointerfaces can fully unleash the multifunctional application potential of composite membrane. The targeted induction method was used to precisely regulate the formation site and morphology of the metal-organic framework precursor, and intelligently integrate multiple heterostructures to enhance dielectric polarization, which improves the impedance matching and loss mechanisms of the electromagnetic wave absorbing materials. Due to the synergistic enhancement of electrospinning-derived carbon nanofiber "stems", MOF-derived carbon nanosheet "petals" and transition metal selenide nano-particle "stamens", the CoxSey/NiSe@CNSs@CNFs (CNCC) composite membrane obtains a minimum reflection loss value (RLmin) of -68.40 dB at 2.6 mm and a maximum effective absorption bandwidth (EAB) of 8.88 GHz at a thin thickness of 2.0 mm with a filling amount of only 5 wt%. In addition, the multi-component and hierarchical heterostructure endow the fibrous membrane with excellent flexibility, water resistance, thermal management, and other multifunctional properties. This work provides unique perspectives for the precise design and rational application of multifunctional fabrics.

Metal-organic framework derived bimetallic selenide embedded in nitrogen-doped carbon hierarchical nanosphere for highly reversible sodium-ion storage

Bimetallic selenides with various valence transitions and high theoretical capacities are extensively studied as anodes for sodium-ion-batteries (SIBs), but their huge volume changes and poor capacity retention limit their practicality. Herein, a facile and controllable strategy using a binary Ni-Co metal-organic framework (MOF) precursors followed by the selenization process, which produced a cobalt nickel selenide/N-doped carbon composite ((CoNi)Se₂/NC) that maintained the hierarchical nanospheres structure. Such a distinctive structure affords both Na⁺ and electron diffusion pathways in the electrochemical reactions as well as high electrical conductivity, thus leading to superior electrochemical performance when the designed composite is utilized as an anode in SIBs. The resulting nanospheres-like (CoNi)Se₂/NC hierarchical structure exhibits a high specific capacity of 526.8 mA h g^-1 at 0.2 A/g over 100 cycles, a stable cycle life with no obvious capacities loss at 1.0 and 3.0 A/g after 500 cycles, and exceptional rate capability of 322.9 mA h g^-1 at 10.0 A/g.

Amino Phenyl Copper Phosphate-Bridged Reactive Phosphaphenanthrene to Intensify Fire Safety of Epoxy Resins

To improve the compatibility between flame retardant and epoxy resin (EP) matrix, amino phenyl copper phosphate-9, 10-dihydro-9-oxygen-10-phospha-phenanthrene-10-oxide (CuPPA-DOPO) is synthesized through surface grafting, which is blended with EP matrix to prepare EP/CuPPA-DOPO composites. The amorphous structure of CuPPA-DOPO is characterized by X-ray diffraction and Fourier-transform infrared spectroscopy. Scanning electron microscope (SEM) images indicate that the agglomeration of hybrids is improved, resisting the intense intermolecular attractions on account of the acting force between CuPPA and DOPO. The results of thermal analysis show that CuPPA-DOPO can promote the premature decomposition of EP and increase the residual amount of EP composites. It is worth mentioning that EP/6 wt% CuPPA-DOPO composites reach UL-94 V-1 level and limiting oxygen index (LOI) of 32.6%. Meanwhile, their peak heat release rate (PHRR), peak smoke production release (PSPR) and CO₂ production (CO₂P) are decreased by 52.5%, 26.1% and 41.4%, respectively, compared with those of EP. The inhibition effect of CuPPA-DOPO on the combustion of EP may be due to the release of phosphorus and ammonia free radicals, as well as the catalytic charring ability of metal oxides and phosphorus phases.

Improving the Thermal Stability and Flame Retardancy of Epoxy Resins by Lamellar Cobalt Potassium Pyrophosphate

In order to improve the fire retardancy of epoxy resin (EP), lamellar cobalt potassium pyrophosphate (LCPP) nanocrystal whiskers with a length of 100-300 nm were designed and synthesized by a liquid technique. LCPP with high thermal stability was blended into EP to prepare the EP/LCPP composites. The results show that the EP/LCPP composites have higher thermal stability and produce more residues compared to pure EP. The combustion results display that the LOI value of the EP/10wt%LCPP composites was significantly improved to 35.9%, and the EP/6wt%LCPP composite can reach a UL-94 V-1 rating. Additionally, the peak heat release rate and peak smoke production rate of the EP/10wt%LCPP composites dramatically decreased by 43.8% and 48.5%, respectively. The improved flame retardancy and smoke suppression are mainly attributed to the inherent physical barrier of LCPP and the excellent catalytic carbonization ability of LCPP.