Fast Capacity Research Articles

High‐Current Capable and Non‐Flammable Protic Organic Electrolyte for Rechargeable Zn Batteries

AbstractWiederaufladbare Zinkbatterien (RZBs) gelten aufgrund ihrer zahlreichen Vorteile als potente Konkurrenten für elektrochemische Geräte der nächsten Generation. Dennoch können herkömmliche wässrige Elektrolyte aufgrund der komplexen Reaktionskinetik in wässrigen Systemen durch schnellen Kapazitätsabfall und schlechte Coulomb′sche Effizienz (CE) ernsthafte Gefahren für den langfristigen Batteriebetrieb verursachen. Wir haben hier die neuartige Verwendung des protischen Amid‐Lösungsmittels N‐Methylformamid (NMF) als Zinkbatterie‐Elektrolyt vorgeschlagen, dass eine hohe Dielektrizitätskonstante und einen hohen Flammpunkt besitzt, um gleichzeitig eine schnelle Kinetik und Batteriesicherheit zu fördern. Die dendritenfreie und körnige Zn‐Abscheidung im Zn‐NMF‐Elektrolyten gewährleistet eine ultralange Lebensdauer von 2000 Stunden bei 2.0 mA cm−2/2.0 mAh cm−2, ein hohes CE von 99.57 %, ein breites elektrochemisches Fenster (≈3.43 V vs. Zn2+/Zn) und eine hervorragende Haltbarkeit bis zu 10.0 mAh cm−2. Diese Arbeit wirft ein Licht auf die effiziente Leistung des protischen nichtwässrigen Elektrolyten, der neue Möglichkeiten zur Förderung sicherer und energiedichter RZBs eröffnen wird.

Ag Plumes Grown on Cu for Li-Lean Anode of High Energy Density Li-Metal Batteries

Li metal combines the advantages of low redox potential and high theoretical specific capacity, being an ideal candidate anode for high energy density secondary batteries. However, Li-metal anode tends to grow dendrites that are highly reactive to electrolyte and cause issues such as fast capacity decaying and safety risk. To address these issues, we propose a Li-lean anode featuring Ag plumes on Cu substrate. The Ag plumes are grown on Cu substrate by immersing Cu foil in AgF aqueous solution, and the Li-lean anode is fabricated by depositing Li on the grown Ag plumes. Thanks to the large specific surface area and the low Li depositing/stripping overpotential of the Ag plumes, the as-fabricated Li-lean anode allows the cell to match with LiFePO4 cathode with excellent cyclic stability. Compared with the bare Cu electrode, the as-fabricated Li-lean anode improves the capacity retention of the cell with a LFP loading of 0.4 mAh cm–2 from 9 to 81% after 300 cycles at 1 C between 2.0 and 4.0 V. The facile formation of Ag plumes makes it possible for high energy density Li-metal batteries to be applied in a large scale.

Lithium–sulfur battery performance enhancement by optimal loading of graphene oxide on separator with MXene/reduced graphene oxide/sulfur cathode

Lithium–sulfur batteries are a compelling choice for next-generation energy storage devices with their high energy density, low cost, and environmental friendliness. This work employs a one-pot route to synthesize a MXene/reduced graphene oxide/S composite with a graphene oxide (GO)-modified separator to overcome the common bottlenecks to successful commercialization of lithium sulfur batteries like fast capacity fade, low electrochemical utilization, and low sulfur loading. The synthesized cathode material was characterized by powder X-ray diffraction, scanning electron microscopy, thermogravimetry, Raman spectroscopy, and X-ray photoelectron spectroscopy. Electrochemical characterization of assembled coin-cells was performed by cyclic voltammetry, galvanostatic cycling as well as by electrochemical impedance spectroscopy. The loading of GO on the separator was varied to probe its effect and a monotonic increase in capacity with increasing GO loading was observed. GO modification of separator also results in lower cell impedance and enhanced Li+ diffusion. The optimized coin cell exhibited an initial specific capacity of 725 mAh/g when cycled at 100 mA/g current density with a capacity fade of 0.14% per cycle. Post-mortem analysis of cycled cells corroborates increased polysulfide trapping with higher GO loading on separator.

Highly Stretchable and Sensitive Strain Sensor Based on Porous Materials and Rhombic‐Mesh Structures for Robot Teleoperation

AbstractWearable sensors for human motion capture offer a promising human–robot interface to control robots in the teleoperation scenario, where robots could function as the second body of human operators to fulfill tasks remotely and accurately. In this paper, a novel strain sensor based on a soft polyurethane (PU) sponge and carbon nanotubes (CNT) is designed for motion capture of human joints. The unique 3D porous microstructure of the PU‐CNT sponge provides the sensor with high sensitivity. To bridge the gap between the high sensitivity and high stretchability of the strain sensor, a rhombic‐mesh structure with optimized geometric parameters, in conjunction with a pre‐compression design, is proposed for strain sensor prototyping, which endows the sensor with an extra elongation rate during the stretching process. The proposed PU‐CNT strain sensor manifests promising sensing performance with a stretchability of up to 300% and a maximum gauge factor of 3893, together with long‐term durability, low detection limit, and fast response capacity. Finally, the validation of the strain sensor is carried out by deploying the sensor on a human elbow to realize the teleoperation of a robot arm, which could be monitored through the digital twin model of the robot in a real‐time manner.

Spinel-structured MnV2O4 @nitrogen-doped carbon microspheres for sodium ion batteries with ultra-long cycle stability

Vanadium oxide is provided with abundant redox centers for high theoretical capacity as anode of sodium-ion batteries (SIBs), but still has poor inherent conductivity and volume expansion leading to fast capacity decay during cycling. In the study, the manganese vanadate microspheres enclosed in nitrogen-doped carbon layers (MnV2O4 @NC) are availably constructed via reflux vanadization of Mn glycerol precursor and in situ thermal decomposition. The MnV2O4 @NC microspheres shows excellent the long-cycle stability as anode materials for SIBs, remaining the specific capacity of 205 mAh g−1 at current of 1000 mA g−1 after nearly 4000 cycles. Due to the increased valence range of bimetallic oxides and three-dimensional channels of spinel structure, the cubic MnV2O4 encapsulated by carbon shell can effectively enhance charge transfer, optimize electronic structure, stabilize crystal structure, and improve cycle stability. These results disclose the prospects of vanadate-based spinel material in high performance SIBs.

Nickel Oxide Decorated Halloysite Nanotubes as Sulfur Host Materials for Lithium-Sulfur Batteries.

Lithium-sulfur batteries with high energy density still confront many challenges, such as polysulfide dissolution, the large volume change of sulfur, and fast capacity fading in long-term cycling. Herein, a naturally abundant clay material, halloysite, is introduced as a sulfur host material in the cathode of Li-S batteries. Nickel oxide nanoparticles are embedded into the halloysite nanotubes (NiO@Halloysite) by hydrothermal and calcination treatment to improve the affinity of halloysite nanotubesto polysulfides. The NiO@Halloysite composite loaded with sulfur (S/NiO@Halloysite) is employed as the cathode of Li-S batteries, which combines the physical confinements of tubular halloysite particles and good chemical adsorption ability of NiO. The S/NiO@Halloysite electrode exhibits a high discharge capacity of 1205.47mAhg-1 at 0.1C. In addition, it demonstrates enhanced cycling stability, retaining ≈60% of initial capacity after 450 cycles at 0.5C. The synthesized NiO@Halloysite can provide a promising prospect and valuable insight into applying natural clay materials in Li-S batteries.

Simultaneous measurement of local current and temperature distributions in proton exchange membrane fuel cells with dead-ended anode

The dead-ended anode (DEA) operation could cause local flooding and local hydrogen starvation in proton exchange membrane fuel cells (PEMFCs), resulting in drastic changes in fuel cell performance. In order to study the detailed local dynamic characteristics of DEA operation, simultaneous measurements of the dynamic variation of local current and local temperature in a PEMFC with DEA have been performed using a local current measurement gasket and micro thermocouples. The results show that the local fuel cell performance distribution gradually becomes uneven during DEA operation and the evolutions of local current and temperature strongly depend on the locations along the flow channel. The highest local current and local temperature are observed near the anode inlet, posing serious threats for the local fuel cell. Furthermore, with anode purging, the current distribution becomes uniform quickly due to the fast mass transfer capacity of hydrogen, but the local temperatures take much longer time to become uniform and stable because of the thermal capacity of fuel cell components. The anode purging also causes local temperature undershoots and the amplitude is over 4℃ in this study. Finally, the effects of operating conditions are discussed. The local current and temperature distributions become more uneven as overall operating current increases and operating temperature decreases. The local temperatures are all reduced as anode inlet pressure and air stoichiometry increase due to the enhanced convection cooling effect. It is demonstrated that measuring local current and temperature is effective in investigating local dynamic performance of PEMFCs with DEA.

High-Entropy Doping Boosts Ion/Electronic Transport of Na4 Fe3 (PO4 )2 (P2 O7 )/C Cathode for Superior Performance Sodium-Ion Batteries.

Fe-based mixed phosphate cathodes for Na-ion batteries usually possess weak rate capacity and cycle stability challenges resulting from sluggish diffusion kinetics and poor conductivity under the relatively low preparation temperature. Here, the excellent sodium storage capability of this system is obtained by introducing the high-entropy doping to enhance the electronic and ionic conductivity. As designed high-entropy doping Na4 Fe2.85 (Ni,Co,Mn,Cu,Mg)0.03 (PO4 )2 P2 O7 (NFPP-HE) cathode can release 122 mAh g-1 at 0.1 C, even 85 mAh g-1 at ultrahigh rate of 50 C, and keep a high retention of 82.3% after 1500 cycles at 10 C. Besides, the cathode also exhibits outstanding fast charge capacity in terms of the cyclability and capacity with 105 mAh g-1 at 5 C/1 C, corresponding 94.3% retention after 500 cycles. The combination of in situ X-ray diffraction, density functional theory, conductive-atomic force microscopy, and galvanostatic intermittent titration technique tests reveal that the reversible structure evolution with optimized Na+ migration path and energy barrier boost the Na+ kinetics and improve the interfacial electronic transfer, thus improving performance.

Zinc-Ion Capacitors with Fast Kinetics at a High Mass Loading

The exploitation of electrode materials with the capability of fast kinetics and high capacity under high mass loading remains a great challenge for zinc-ion capacitors (ZICs). Herein, spherical superstructures of N-doped carbon nanorods (SSNCR-x) are developed to substantially boost the kinetics and Zn2+ storage capability of ZICs. The optimized SSNCR-800 features a gradient carbon nanorods framework with a hierarchical porous structure for facilitating ion diffusion and electron transfer, enabling impressive properties for Zn2+ storage. Consequently, SSNCR-800 displays a highly fascinating property in terms of capacitance and cycle stability as the cathode of ZICs, delivering pronounced energy density (181.2 Wh kg–1) and power density (31.1 kW kg–1), as well as long lifespan with 93.5% capacitance retention after 50,000 cycles. Moreover, the constructed ZICs showcase a high specific capacitance of 215 F g–1 and 91.7% capacitance retention after 10,000 cycles under a mass loading of 50 mg cm–2. Systematic characterization demonstrated that the unique structure peculiarity of SSNCR-800 with high-speed mass transfer channels and abundant accessible electrochemical active sites endows the ZICs with fast kinetics and outstanding capability for Zn2+ storage. This work provides an opportunity to overcome the trade-off between the fast kinetics and high mass loading of ZICs toward practical applications.

Investigation of the radioprotective properties of Zingerone, Ibuprofen, and Sulfasalazine against neutron radiation damage

Nuclear radiation (neutron, gamma X rays, etc.) is widely used in power generation, industry, medicine, research, and agriculture. Exposure to ionizing or indirect ionizing radiation can cause mutagenetic cell death depending on the dose and duration. It is important to reduce the carcinogenesis of cancer patients undergoing radiotherapy treatment and people working in radiation fields. Neutrons have wide applications in neutron activation analysis (NAA), neutron capture therapy (NCT), neutron radiography (NR), neutron capture, neutron conversion doping (NTD) sample irradiation, and neutron diffraction (ND). In these applications, protective substances are needed to stop the neutrons from entering the body and to reduce their effects. In this work, the use of zingerone, ibuprofen, and sulfasalazine compounds as active ingredients in a neutron protective drug was investigated. Some important neutron attenuation parameters such as an effective removal cross section, mean free path, half-value layer, and transmission number were theoretically calculated with the Monte Carlo simulation GEANT4 code for fast and epithermal neutrons.The 241Am-Be fast neutron source and a BF3 gaseous detector were used to determine the neutron absorption ability of all of the samples. All of the results were compared with paraffin, which has a good shielding capacity. According to the results, it was found that every examined sample had a fast and epithermal neutron absorption capacity. It reported that the dose amount from the source was absorbed by the samples at rates of 33.37% (DAI1), 34.85% (DAI2), and 34.21% (DAI3). It was determined that the DAI2 sample in particular had a high absorption ability ratio compared to other samples. Because this sample have high hydrogen content than others samples. So, it was shown that these compounds can be used as active substances to make a radioprotective drug.

Event-Triggered Adaptive Hybrid Torque-Position Control (ET-AHTPC) for Robot-Assisted Ankle Rehabilitation

Ankle rehabilitation for increasing number of strokes is highly demanded, and robot-assisted approach has shown great potential. Since the required movement and force assistances will concurrently change during rehabilitation sessions, the robotic assistances are supposed to be adjusted accordingly. In order to achieve both adaptive torque and synchronous position control for the robot in practice, a novel event-triggered adaptive hybrid torque-position control (ET-AHTPC) is proposed for a developed ankle rehabilitation robot driven by pneumatic muscles (PM). In the novel adaptive torque control scheme, the assistive torque adapted to the patient's recovery state is adjusted by a designed robot-assisted rehabilitation index mapping from the clinical assessment scale. The robotic assistance output is online corrected by patient's performance, based on a correcting index calculated by interaction torque and tracking errors. Then a model-based event-triggered optimal position controller is established and a critic neural network (NN) is introduced to reduce the control law update frequency for fast trajectory tracking. The stability of the overall system is proved by Lyapunov theorem. A series of experiments were conducted on the ankle rehabilitation robot to validate the controller's fast trajectory tracking and adaptive assistance capacity, which can online adjust the robot's assistive torque and allowable movement range for patients at different recovery stages.

Functionalized magnetic covalent organic framework nanocomposites for high‐efficiency adsorption of ethyl carbamate from liquor

AbstractEthyl carbamate (EC) is a kind of genotoxic and carcinogenic substance and potentially harmful to human health. In this study, simple and effective removal of EC from liquor samples by using the magnetic mesoporous adsorbent (Fe3O4@COFs) was investigated. Gas chromatography and triple quadrupole tandem mass spectrometry (GC‐MS/MS) was used to monitor the whole of adsorption process. The results showed that the adsorbent has high efficiency and fast adsorption capacity. Under the optimized adsorption parameters, pseudo‐first‐order and pseudo‐second‐order kinetic models were employed to reveal the underlying sorption mechanism. Results indicated that the adsorption of EC on Fe3O4@COFs is more consistent with the pseudo‐second‐order model. Furthermore, an effective method for the adsorption and detection of EC was successfully developed, which exhibited good linearity with R2 ranging from 0.9954 to 0.9998, satisfactory recoveries in the range of 86.9%–116.2%, and the relative standard deviations (RSD) was lower than 5.8%. Fe3O4@COFs showed good stability and excellent performance in removing EC from liquor samples. It is expected that the proposed magnetic COFs hold great promise for liquor sample pretreatment and be extended for application in other fields.

Typical cathode materials for lithium‐ion and sodium‐ion batteries: From structural design to performance optimization

AbstractRechargeable lithium‐ion and sodium‐ion batteries (SIB) have dominated the energy storage fields such as electric vehicles and portable electronics due to their high energy density, long cycle life, and environmental friendliness. However, the critical bottleneck hindering the further improvement of their electrochemical performance is the unsatisfactory cathode materials, typically exhibiting inherent drawbacks such as low reversible capacity, initial capacity loss, fast capacity decay, and poor rate performance. These issues are mainly attributed to changes in the internal structure of cathode materials, such as irreversible transformation of particle morphology, evolution of crystal structure, and undesired physicochemical interfacial reactions during the electrochemical process. To address above obstacles, abundant research efforts have been devoted to stabilizing the structural evolution of cathode materials and enhancing their electrochemical performance. Herein, we reviewed the research progress on the cathode materials for lithium‐ion and SIBs. The typical cathodes and their structural characteristics, electrochemical behaviors, reaction mechanisms, and strategies for electrochemical performance optimization were summarized. This review aims to promote the understanding of the structure‐performance relationship in the cathode materials and provide some guidance for the design of advanced cathode materials for lithium‐ion and SIBs from the perspective of crystal structure.

Facile synthesis of imidazolium cationic organic polymer with ultrafast ReO4−/99TcO4− removal under highly alkaline conditions

It is already known that nuclear power can reduce the greenhouse gas emissions, while must clear its release of a few but hazardous nuclear wastes. Therefore, there is an urgent need to rational design adsorption materials in order to excellent eliminate the radioactive contaminations, including the most potentially problematic technetium-99 (99Tc). Herein, we present an easily synthetic approach to prepare a robust imidazolium-based cationic organic polymer (denoted as PMV3m-Cl) in a low-cost, through vinyl polymerization via a tri-imidazolium-charged monomer. Due to the synergetic effects of physical adsorption and ion exchange, PMV3m-Cl featured ultrafast 99TcO4− (as well as its nonradioactive surrogate ReO4−) adsorption kinetics, with the performance of 99 % removal within 1 min (at a relatively low solid-to-liquid ratio of 0.2 g/L). PMV3m-Cl also displayed high adsorption performance of ReO4− over a wide range of pH values, and remained up to 94 % removal rate after five cycles of adsorption/desorption. Even in extreme alkaline (3 M NaOH) solution, it can remain stable and rapidly remove ReO4−, to reach the adsorption equilibriums at 30 s with a recorded removal efficiency of 79 %. Furthermore, it is noting that PMV3m-Cl enables to decontaminated low concentration (∼10 ppm) ReO4− contaminated potable water to residue of 7% within 1 min. The fast kinetics, excellent selectivity, and high uptake capacity (739 mg/g for ReO4−) of PMV3m-Cl were attributed to that the framework is rich in positively charged imidazole segments exhibiting the strong electrostatic interactions and binding affinity with ReO4− and 99TcO4− ions. Results of this study suggest PMV3m-Cl is a promising adsorbent for the removal of ReO4− and 99TcO4−, and provide valuable reference significance to design an alkaline resistant nuclear associated environmental remediation material.

Determination of toxicity and radioprotective properties of bacterial and fungal eumelanin pigments

Purpose Determination of the protective property of melanin, an organic polymer class consisting of phenolic and/or indolic compounds isolated from bacteria and fungi, against fast neutron radiation. To show that these melanin samples, which also have antioxidant and metal chelating properties, can be used as an active ingredient for a drug to be developed against neutrons used in nuclear research and medicine. Materials and methods Bacterial and fungal media were prepared, and melanin pigments were produced and isolated. For molecular characterization of pigments, bacterial genomic DNA extraction, 16S rDNA gene amplification processes, and fungal genomic DNA extraction, ITS1, and ITS4 Gene Regions amplification were performed. The DEL assay was implemented to determine the genotoxicity properties of bacterial and fungal melanin pigments. Samples were prepared in a pad measuring 10 ml volume (60 × 15 mm) at a concentration of 0.2–1 microgram in 1% agarose gel for radiation-absorbed dose measurements. Absorption measurements were made using 241Am-Be fast neutron source and Canberra brand NP series BF3 gaseous detector to determine the neutron radiation absorption capacity of all samples. The results obtained to determine the absorption degrees of melanin samples were compared with paraffin and normal concrete, which are widely used in neutron radiation shielding studies. Results Melanin pigments were obtained using different bacteria and fungi strains. Afterwards, the fast neutron radiation absorption capacity of these purified pigments were determined. Compared to reference samples, these pigments were found to have slightly lower radiation absorbing ability. In addition to these experiments, cytotoxicity tests were carried out using the Yeast DEL assay technique to evaluate the potential for use of these organic pigments in fields such as medicine and pharmacology. According to the results obtained from the tests, it was determined that these melanin samples did not have any toxic effects. Conclusion It was determined that these melanin samples have the potential to be used as a radioprotective drug active substance to protect the tissues and cells of people exposed to neutron radiation after a nuclear accident or nuclear war. Giving a drug that will be developed by using these active ingredients before or after people are exposed to a radiation environment can provide great benefits.

Choline chloride/urea etched carbon fiber to improve the elasticity of biomass-based carbon aerogel for efficient oil-water separation

Carbon aerogel prepared using waste biomass as the carbon source can be utilized as the ideal absorption material for the remediation of oil spill accidents. However, the brittleness of the fiber and agglomeration of precursor fiber chains due to hydrogen bonding leads to poor mechanical properties and low absorption capacity of the carbon aerogel. The doping treatment used to overcome such defects still shows some deficiencies, such as high cost, cumbersome process, and part of the process involving toxicity. To overcome the agglomeration between the cellulose chains, a chemically-etched biomass-based carbon aerogel (EBCA) was prepared using pineapple cellulose nanofiber (CNF) etched by the deep eutectic solvents (DES) of choline chloride/urea under a low carbonization temperature of 400 °C. The as-prepared material, designated as EBCA-400, possesses a 3D structure with a huge BET specific surface area of 501.56 m2 g−1, a density of only 0.032 g cm−3 and a porosity of 97.3% with excellent elasticity performance and self-recovery performance owing to the enhancement of the surface roughness of fibers through DES etching. Also, EBCA-400 shows a superhydrophobicity with a water contact angle (WCA) of 157.6° and has a strong and fast absorption capacity for various oils in various scenarios, the absorption capacity for CCl4 reaches 288 times its own weight, and the absorption efficiency to CCl4 can still reach more than 97% of the maximum value even after 15 oil absorption-removal cycles. With the characteristics of very low density, huge porosity, excellent elasticity and superhydrophobicity as well as better reusability, EBCA-400 has great potential in oil spill remediation. This study provides a convenient and environment-friendly way for surface modification to improve the elasticity of carbon aerogel, which is crucial to the recovery of carbon aerogel for its reusability.

Construction of mesoporous Si-Fe-GO composite for the highly efficient removal of uranium

The mesoporous Si-Fe-GO composite was prepared by sol–gel method to remove uranium. In the static adsorption process, the Si-Fe-GO composite possessed strong uranium-chelating ability with fast uranium adsorption kinetic (120 min) and high uranium adsorption capacity (576.4 mg/g). The adsorption behavior perfectly followed the pseudo-second-order kinetic and Langmuir isotherm models, revealing the nature of monolayer chemical adsorption. The tolerance experiments of coexisting ions showed that the Si-Fe-GO composite possessed a strong affinity for uranium, which was beneficial for the enrichment of uranium in a multi-component wastewater system. The good regeneration ability also reflected the practical application value of the Si-Fe-GO composite. Besides, the dynamic adsorption studies showed that the Si-Fe-GO composite might be suitable for the remediation of uranium-containing wastewater with low flow rate and low uranium concentration. In conclusion, this work would contribute to the development of functional SiO2 materials for water remediation and meet the practical requirements for the cleanup of uranium from wastewater.

Design considerations and cycling guidance for aluminum foil anodes in lithium-ion rechargeable cells

Al foil is an attractive anode candidate for Li-ion rechargeable batteries, but the systemic problem of fast capacity degradation limits its re-introduction in practical applications. Partial lithiation-delithiation does mitigate the issue to a certain degree, but the cycle life is still tied to the problems associated with the phase transformation between β-LiAl and α-Al. Utilizing the solubility range of β-LiAl has been proven to be a feasible approach to stabilize the β-LiAl grown on an Al foil, i.e., the β-LiAl(Al) anode, but the electrochemically driven ion transport limitations of this electrode remain largely unclear. Herein, we present comprehensive electrochemical analyses of the β-LiAl(Al) electrode to shed light on its kinetic limitations which have intrinsic links to the electrode thickness and total cell capacity. Results show that the β-LiAl(Al) electrode can be charged at a C-rate as high as 2.9 C when a proper prelithiation is done for an Al foil. The superior rate capability is suggested to partly originate from the fast lithium diffusion in β-LiAl: -10−7 cm2·s−1 at room temperature. Furthermore, the cells consisting of β-LiAl(Al) vs. commercial Li4Ti5O12 exhibit promising cycling performances, even at 10 mA·cm−2, giving 300 cycles with a capacity retention of ∼80%. With a systematic investigation of the limiting mechanisms focusing on correlating the prelithiation depth and the cycle life, the cyclability of the β-LiAl(Al) electrode at different current densities (0.5–10 mA·cm−2) is mapped out, providing comprehensive guidance for the practical utilization of the β-LiAl(Al) anode in a range of Li-ion cell types, from all-solid-state batteries to hybrid capacitors.

BiSbx nanoalloys encapsulated by carbon fibers as high rate sodium ions storage anodes

BiSbx is a promising anode material for sodium ion batteries because of its merits in tolerating fast charge transfer during cycles. Here, a simple electrospinning is adopted to produce the BiSbx nanoalloys. One-dimensional (1D) carbon fibers with 30 ∼ 50 nm BiSbx nanoparticles uniformly encapsulated inner (denoted as BiSbx@C) was fabricated. The as-prepared BiSbx@C anodes exhibit unexpected rate capability for sodium ions storage, withstanding a high current density of 20 A g−1 and delivering a reversible capacity of 500.2 mAh g−1 and 86.4% capacity retention after 100 cycles, which can be attributed to the bimetallic nanoalloys combined with 1D carbon that tolerate fast capacity fading during cycling and accommodate the volume expand during cycling. Specially, deeper understanding of the underlying mechanism of the Na+ ions storage and rapid transfer capability is civilized, which is vital to advance the sodium ions batteries for commercialization.

One-pot K+ and PO43− co-doping enhances electrochemical performance of Li-rich Li1.2Ni0.13Co0.13Mn0.54O2 cathode for Li-ion battery

The high specific capacity and voltage of Li-rich Mn-based oxides make them promising cathode materials for high-energy-density lithium-ion batteries (LIBs). However, the problems such as low initial coulombic efficiency, fast capacity and voltage fading, poor kinetics, large voltage hysteresis, and poor safety performance hamper their fast commercialization. Herein, we report one-pot K+ and PO43− co-doping Li-rich Mn-based oxides Li1.2Ni0.13Co0.13Mn0.54O2 cathode material to improve the electrochemical performance of the lithium-ion battery. On the one hand, K+ doping can stabilize the bulk structure and enlarge the Li slabs to facilitate the diffusion of Li+, resulting in enhanced cycling and rate performance. On the other hand, PO43− doping changes the electronic structure of the material and weakens the covalency of TM-O, decreasing the irreversible loss of lattice oxygen and stabilizing the structure. As a result, the K+ and PO43− co-doping can effectively alleviate the capacity and voltage decay and the modified sample shows better cycling stability (88.6%@0.5 C@250 cycles) and rate performance (155.5 mAh g −1@5 C) compared to the pristine material. Our strategy here provides a facile one-pot method to modify Li-rich Mn-based oxides cathode material for high-performance LIBs.