Search

Ti 3 C 2 MXene-based composites are emerging two-dimensional (2D) layered materials promising in electrochemical energy storage devices such as rechargeable ion batteries and supercapacitors. However, scalable preparation of Ti 3 C 2 MXene-based composites , especially, integrated with one-dimensional (1D) materials through a facile low-temperature strategy remains a considerable challenge. Herein, novel sandwich-like Na 0.23 TiO 2 /Ti 3 C 2 composites made of 1D amorphous Na 0.23 TiO 2 nanobelts growing on 2D Ti 3 C 2 nanosheets have been prepared through a one-step scalable transformation reaction of Ti 3 C 2 MXene. The sandwich-like Na 0.23 TiO 2 /Ti 3 C 2 composites comprising of 1D ultrathin nanobelts, 2D conductive nanosheets and 3D sandwich-like architecture with electrically connecting interfaces inside can effectively relieve strain of the electrode upon cycling, facilitate carrier transport dynamics and protect aggregation of the electrode material, favorable for high-performance rechargeable batteries. As a result, when employed as anodes in Li/Na-ion batteries, the Na 0.23 TiO 2 /Ti 3 C 2 electrodes exhibit superior long cycling stability (up to 4000 cycles at the high rates with respective capacity retention of over or nearly 100%), and remarkable rate capability. This work may open a new way for scalable synthesis of 2D layered MXene-based composites with desired architectures and properties for practical energy applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Large-scaled PPS ultrafine fibers with uniform size (0.8–1 µm in diameter) are first fabricated by low cost melt spinning technology. • The safe PPS/mGNFs hybrid separators with hierarchical structure are fabricated via a facile papermaking strategy. • The multilevel structure, porosity, polarity and mechanical properties of hybrid separators are controllable. Separators play a critical role in the safety and electrochemical performance of lithium-ion batteries (LIBs). However, the commercial polyolefin-based separators encounter poor thermal stability and flame retardance, which have aroused severe safety issues. Herein, a flexible and heat-resistant porous separator based on sea-island polyphenylene sulfide (PPS) ultrathin fiber and glass nanofiber (GNF) network is rationally designed and successfully fabricated. This hierarchical network is bound via hot pressing and modification of silane coupling agent (γ-3-glycidoxypropyltrimethoxy silane, γ-GPS), endowing the separator with high flexibility and excellent mechanical performance. Also, this novel composite separator features distinguished thermal stability (without any heat shrink at 250 °C for 30 min) and flame retardant properties, guaranteeing the safety of the battery. Due to the inherent polarity and porous structure, the as-prepared PPS-mGNFs separator achieves a small contact angle (18.2°) of liquid electrolyte (LiPF 6) and a high electrolyte uptake (253%), implying much better electrolyte wettability than the commercial polyolefin separator. In addition, the LIB integrated with PPS-mGNFs separator exhibits excellent discharge capacity, C-rate performance and cycling performance. This facile and promising strategy provides a platform for the large-scale fabrication of high-performance and safe LIB separators. [ABSTRACT FROM AUTHOR]

Developing high-capacity electrode materials is critical to enhance the energy-density of lithium-ion batteries. Here, a new graphene nanoplatelets-supported SiO x -disordered carbon composite (SiO x -C/GNPs) is fabricated by a Stöber-type process and high-temperature treatment. When used as an anode for lithium-ion batteries, SiO x -C/GNPs exhibits excellent cycle stability and rate capability even under deep charge–discharge cycling. A stable reversible capacity of about 630 mAh g −1 (calculated on the total mass of the composite) can be achieved at a current density of 100 mA g −1 and the capacity retention is nearly 100% after 250 cycles. Additionally, the plateau voltages of lithium extraction for the composite are only slightly higher than those for the commercial graphite, which ensures the high energy density of the assembled batteries. The superior electrochemical performance of this novel material is due to its unique features: excellent electronic conductivity, short transportation length for both lithium ions and electrons, elastomeric space to accommodate volume changes upon Li insertion/extraction and robust connection between SiO x and GNPs. [ABSTRACT FROM AUTHOR]

Self-supported and flexible highly porous carbon nanofibers (HPCNFs) were prepared by electrospinning method combined with a post-two-step carbonization process. By introduction of air into the Ar flow during carbonization, carbon nanofibers were partially burnt off and a large number of micro/mesopores were created. As effective lithium storage units, the porous structure plays an important role in enhancing the electrochemical performances. The HPCNFs delivers a reversible capacity as high as 1780 mAh g −1 after 40 cycles at 50 mA g −1 and ultralong cycle life (1550 mAh g −1 after 600 cycles at 500 mA g −1 ). Even cycled at 25 A g −1 , it still displays a very high capacity of 200 mAh g −1 . The outstanding electrochemical and mechanical properties of HPCNFs are attributed to the novel structure: pores provide good access of the electrolyte to the electrode surface and facilitate fast charge transfer across the electrode/electrolyte interface. 3D interconnected networks decrease the contact resistance and improve electrical conductivity of the overall electrode, which enhance electron transport rate. Therefore, this novel carbon material holds great promise for potential applications in energy-related technological and flexible electrodes for next generation LIBs. [ABSTRACT FROM AUTHOR]

Highlights: [•] Double-shelled Mn2O3 hollow microspheres are prepared by a multi-step. [•] synthesis procedure. [•] Solid, hollow and yolk-structured Mn2O3 spheres are prepared for comparison. [•] The double-shelled hollow Mn2O3 is superior in electrochemical properties. [ABSTRACT FROM AUTHOR]

Abstract: In this study, AlF3 was successfully coated on the surface of LiV3O8 nanosheets, as verified by transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX). AlF3 coated LiV3O8 exhibited the significantly improved cycling stability with the capacity retention of ca. 91% over 50cycles at 150mAg−1, while that of the bare one was only 61%. When cycling at 55°C, the bare electrode delivered a much larger capacity loss (44.8%) in comparison with that (19.1%) of the coated one. On the basis of the XRD, CV and EIS results, it was suggested that the AlF3 coating layer could protect the bulk material well and facilitate the kinetics of Li-ion diffusion, leading to smaller electrochemical impedance, thus resulted in improvement of cycling stability for LiV3O8. [Copyright &y& Elsevier]

Abstract: Three-dimensional (3D) porous amorphous SnO2 thin films were deposited on Ni foam substrates by Electrostatic Spray Deposition (ESD) technique as anodes for Li-ion batteries. These films display good capacity retention of 94.8% after 100 cycles at 0.5C and rate capability of 362mAh/g at 10C. The improved performance originates from the fact that the 3D porous structure offers a “buffer zone” to accommodate the large volume change during cycling, and the foam-like substrate maximizes the contact area between electrode and electrolyte. The facile ESD method can be potentially extended to prepare other 3D porous functional materials. [Copyright &y& Elsevier]

Poly (phenylene sulfide) ultrafine fiber is one kind of high-performance fiber with high specific surface area, corrosion resistance, chemical and thermal stability, which can be widely applied in various domains. However, there are few reports about the review of PPS ultrafine fiber. To meet this demand, the paper provides an overall investigation about the fabrication process of PPS ultrafine fiber including sea-island melt spinning, melt electrospinning and melt-blown spinning as well as the application of PPS ultrafine fiber based materials like high temperature filter, lithium ion battery separator, high strength and high modulus composites, oil/water separation membrane, catalytic, adsorption, degradation membrane and so on. Unlabelled Image • The paper provides an overall investigation about the fabrication process of PPS ultrafine fiber including sea-island melt spinning, melt electrospinning and melt-blown spinning. • The paper provides an overall investigation about the features of PPS ultrafine fiber. • The paper provides an overall investigation about the application of PPS ultrafine fiber based materials like high temperature filter, lithium ion battery separator, high strength and high modulus composites, oil/water separation membrane and so on. [ABSTRACT FROM AUTHOR]

• Non-flammable electrolyte with TMP and F-EPE improves the safety of SIB. • TMP/F-EPE electrolyte stabilizes the interface of NFM cathode during all processes. • The cycling life of NFM/HC pouch cell increases by using TMP/F-EPE electrolyte. Despite their beneficial effect on battery safety, non-flammable electrolytes often have an adverse side effect on the electrochemical performance of lithium and sodium ion batteries due to their poor compatibility with the electrodes. In this paper, we report a new non-flammable electrolyte consisting of trimethyl phosphate (TMP) and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (F-EPE) as non-flammable solvents and fluoroethylene carbonate (FEC) as additive with different concentration of Na salts, and a EC-DEC-FEC electrolyte was also prepared as baseline electrolyte. The flammability and non-flammability of the prepared electrolytes was tested. It is shown that the prepared electrolyte not only increases the capacity (129.9 vs. 122.5 mAh g−1 of baseline electrolyte) of NaNi 1/3 Fe 1/3 Mn 1/3 O 2 (NFM) cathode but also stabilizes the cyclability (70.8% retention after 500 cycles) of NFM/HC (HC: hard carbon) pouch cells. The dissolution of pristine NaNi 1/3 Fe 1/3 Mn 1/3 O 2 cathode material in different solvents and electrolytes, and the XPS patterns of the cycled NFM cathode in the prepared electrolytes were also studied to understand the capacity fading mechanism. These results indicate that this new non-flammable electrolyte holds great potential for application in rechargeable sodium-ion batteries. [ABSTRACT FROM AUTHOR]

• A dissociated solvation cluster dominated by NO 3 − is proposed to regulate the effects of cathode interface phase transition and cyclic fragmentation. Existing methods, including our previous work, typically study the effects on the anode interface structure, which are difficult to solve the interface problem generated by the cathode. Thus, we have developed a unique approach to enhance the solubility of LiNO 3 in carbonate electrolyte systems by employing a novel local high-concentrated addition strategy with triethyl phosphate (TEP) as a co-solvent. • Distinct solvation clusters are constructed in NO 3 − dominated electrolyte. Here, Our research focuses on dissociative solvation clusters dominated by NO 3 −, by studying the specific complexation behavior of NO 3 − and Li+. there are two distinct solventization clusters. One is the PF 6 − dominated solvation cluster (PSC) while the FEC is distributed in the outer layer with a loose solvation, and the other is the tight NO 3 − dominated solvation cluster (NSC). The NSC has weak ionization and fast diffusion properties. The PSC also has a reduced binding energy and increased coordination distance Adjacent to NSC. It is attributed to the interactions induced by the TEP and the DMC/FEC in PSC. Thus, the coordination environment of PSC is further loosened, leading to the enhanced diffusion ability of Li+ and PF 6 −, which affects the cathode-electrolyte interface process between the cathode and electrolyte. • The tight NO 3 − dominated solvation cluster improves the electrochemical kinetics process. The uniformly distributed induced Li-N composite interfacial CEI layer generated by the tight NO 3 − dominated solvation cluster accelerates the interfacial Li+ conduction, improves the stability of the interfacial interface, and effectively inhibits the phase transition and stress fracture in the charge–discharge process. • Achieving excellent compatibility with high-voltage NCM cathodes and an excellent electrochemical performance. Stable coulombic efficiency and improved cycling stability were achieved. Full battery cycle performance using NCM811 cathode 0.5C initial discharge specific capacity up to 189 mAh/g, after 300 cycles still has 152 mAh/g discharge specific capacity, capacity retention rate of 80%. The specific discharge capacity of 165 mAh/g is still available under high magnification test conditions (5C). To meet the demand for higher energy density in lithium-ion batteries, extensive research has focused on advanced cathodes and metallic lithium anodes. However, Ni-rich cathodes suffer from the inactive phase-transition and side reactions at the cathode-electrolyte interfaces (CEI). In this study, we propose a novel approach to enhance the solubility of LiNO 3 in carbonate electrolyte systems using a local high-concentrated addition strategy with triethyl phosphate as a co-solvent. Rather than the traditional solvent-dominated solvation clusters, the NO 3 − dominated electrolyte is examined to elucidate unique complexation phenomena. Two distinct clusters in NO 3 − dominated electrolyte arising from as a consequence of intramolecular interactions intrinsic to the constituents. This promotes the formation of a homogeneous oxynitride interphase and facilitates more expeditious lithium ion diffusion kinetics. Hence, the less stress fragmentation and irreversible phase transformation occur on the cathode surface with the homogeneous oxynitridation interface. This innovative design enables efficient cycling of the Li || NCM811 cell, offering a promising strategy to improve lithium-ion batteries performance. [ABSTRACT FROM AUTHOR]

Heteroatom-doped carbon nanomaterials with well-defined porous are used as anode materials for SIBs due to their exceptional structural characteristics. In this work, porous N-doped carbon networks composed with ultrathin carbon nanosheets were synthesized via the direct pyrolysis of Vitamin B5. The content of nitrogen, specific surface area, porous structure of the N-doped carbon nanosheet networks were adjusted by changing reaction temperatures. The formation mechasim of the ultrathin N-doped carbon nanosheet networks was also proposed. The generation of calcium carbonate/calcium oxide used as a self-template renders the formation of the porous structure via thermal treatment. The optimized samples possess a superior lithium and sodium storage: 1534 mAh g −1 at 100 mA g −1 vs. Li/Li + and 335 mAh g −1 at 100 mA g −1 vs. Na/Na + , with nearly 100% cycling Coulombic efficiency, remarkable cycling retention and high rate capacity. Additionally, good electrocatalytic activity for ORR via a 4e −1 pathway determines that the resulting primary Zn-air battery showed high discharge power energy density (80 mW cm −2 ), high reversibility and stability over continuous cycles. [ABSTRACT FROM AUTHOR]

The polished commercial zinc foil as the current collector and thiourea (TU) as the electrolyte additive are studied systematically to improve the performance of LiMn 2 O 4 /Zn aqueous battery. The results show that the coulombic efficiency and the cycling performance are significantly improved by using the polished zinc foil as the anode current collector. Moreover, the TU addition increases the cycling performance of LiMn 2 O 4 /Zn battery and decreases the float charge current density of the battery at room as well as high temperature. X-ray diffraction (XRD) and scanning electron microscopy (SEM) tests confirm that there is nearly no effect of TU in the electrolyte on the crystal structure of LiMn 2 O 4 electrode. However, the addition of TU has an indirect effect on the morphology. Cyclic voltammetry (CV) and deposition–dissolution measurement demonstrate that TU is stable on the cathode electrode and it is able to adsorb to the surface of the zinc anode current collector. As such, the deposition–dissolution efficiency and energy efficiency are improved, which also can be attributed to faster deposition–dissolution and smaller self-discharge process of zinc. [ABSTRACT FROM AUTHOR]

Nitrogen-doped 3D graphene frameworks (N-3D GFs) were synthesized by a facile two-step method: Polystyrene (PS) encapsulated in graphene oxide (GO) composites (denoted as PS@GO) are first synthesized, followed by a post–thermal annealing in ammonia step to get N-doped 3D GFs. The resulting N-3D GFs inherit the advantages of graphene, which possesses high electrical conductivity and high specific surface area. Furthermore, the well-defined 3D interconnected structure can facilitate the access of the electrolyte to the electrode surface, thus shortening the diffusion length of both Li + /e − , keeping the overall electrode highly conductive and active in lithium storage. Simultaneously, the in-situ formation of pyridinic N and pyrrolic N in 3D GFs provide high electronic conductivity and structure stability for lithium storage. The designed N-3D GFs electrode delivers a high specific capacity of 1094 mAhg −1 after 100 cycles at 200 mAg −1 and superior rate capability (691 mAhg −1 after 500 cycles at 1000 mAg −1 ) when used as anode for LIBs. We believe that such an inherently inexpensive, scalable, facile method can significantly increase the feasibility of building high performance energy storage system. [ABSTRACT FROM AUTHOR]

Composites consisting of graphene nanosheets (GNSs) decorated with amorphous TiO 2 thin films were synthesized by an atomic layer deposition (ALD) technique. It was revealed that the TiO 2 thin films were uniformly deposited onto the worm-like GNSs. When used as anode materials in lithium ion batteries (LIBs), the TiO 2 –GNS composites deliver a stable capacity of ~ 140 mAh g − 1 after 100 cycles at a specific current of 100 mA g − 1 as well as superior rate capability, accounting for a sustainable 95 mAh g − 1 capacity at a specific current of 1200 mA g − 1 . It is believed that the remarkable electrochemical performance lied in the unique features of the composites, i.e., the amorphous nature of the TiO 2 films and the large surface area of GNSs. The former rendered short Li + diffusion pathways in TiO 2 thin film, while the latter offered excellent electronic conductivity as well as a large intimate contact area between the electrolyte and TiO 2 . This work laid a venue for designing new electrodes for high-performance LIBs. [ABSTRACT FROM AUTHOR]

The gram-scale synthesis of graphene based mesoporous SnO 2 composite (G-M-SnO 2 ) has been successfully realized based on kirkendall effect. When used as anode for lithium ion batteries, it delivers a high reversible capacity of 1354 mAhg −1 after 50 cycles at 100 mAg −1 and excellent rate capability of 664 mAhg −1 at 2 Ag −1 . The outstanding lithium storage performance mainly results from the synergistic effect of the ultrasmall SnO 2 and conductive graphene nanoparticles, which not only enhanced the conductivity of the whole electrode but also provide buffer matrix for the expansion of SnO 2 nanoparticles during charge-discharge process. Furthermore, the ultra-small size of SnO 2 shortens the diffusion length of Li + /e − in SnO 2 . [ABSTRACT FROM AUTHOR]

Abstract: Br-doping Li4Ti5O12 (Li4Ti5O11.7Br0.3) is fabricated by conventional solid state method and shows enhanced cycling performance compared with pristine Li4Ti5O12. After thermal nitridation for 90 min in NH3, the Li4Ti5O11.7Br0.3 electrode exhibits better rate capability and excellent cycling performance. It delivers a reversible capacity of 138 mAh g−1 and 104 mAh g−1 after 100 cycles at 10C and 20C, respectively, which is approximately four and seven times higher than those of pristine Li4Ti5O12 at the same current rates. This work indicates the feasibility of improving cycling performance and rate capabilities of Li4Ti5O12 through controlling both surface termination and bulk doping procedures. [Copyright &y& Elsevier]

Abstract: Liquid nitrogen was used as a coolant in the freeze-drying method to synthesize nano-Li3V2(PO4)3/reduced graphene oxide (LVPGN) for the first time. In this material, reduced graphene oxide (rGO) (6.6 wt% in content) formed a 3D-framework and Li3V2(PO4)3 nanoparticles (30–150 nm) were strongly adhered to the surface of the rGO and enwrapped into the rGO sheets uniformly. The LVP nanoparticles can decrease the lithium ion diffusion length and the rGO can effectively improve the electronic conductivity. The material shows great rate performance with a capacity of 105.7 mAh g−1 at 20C for 3.0–4.3 V, and a good cycling performance with a discharge capacity of 123.2 mAh g−1 (96.7% of the first discharge capacity 127.4 mAh g−1) after 100 cycles at 0.1C. [Copyright &y& Elsevier]

Here we demonstrated porous carbon nanofibers encapsulated with crystalline red P (P-PCNFs) as free-standing anodes for LIBs with high specific capacity and excellent electrochemical cycling. The porous carbon nanofibers were fabricated by electrospinning of polyacrylonitrile/poly(methyl methacrylate) (PAN/PMMA), followed by thermal carbonization process. The P-PCNFs delivered an excellent cyclability (~2030mAhg-1 at 0.1C rate after 100 cycles) and outstanding rate capability (380mAhg-1 at 11C for 10 cycles), where those capacity values were calculated based on the red P percentage. Even at a rate of 1C, this composite could deliver a superior capacity of 1042mAhg-1 based on the content of red P after 100 cycles. The pores of porous carbon nanofibers could effectively accommodate the volume change of crystalline red P during cycling. Furthermore, the carbon nanofibers matrix not only enables fast access of ions but also grants the electrode with good conductivity and high mechanical flexibility. [ABSTRACT FROM AUTHOR]

Abstract: Overcharge safety is the most crucial problem facing especially large-sized lithium-ion batteries (LIBs) packs owing to the inevitable inhomogeneity of charge-state for each cell. We propose a fresh safety strategy to avoid overcharging, i.e. the use of a solid-state anti-overcharge additive to perform an intrinsic overcharge protection. The mechanism is triggered from a solid-state composite cathode obtained by typically mixing a pre-selected transition-metal oxide with a certain cathodes thus constituting a composite cathode. The effectiveness of this strategy is demonstrated with an example of LiCoO2/CuO (95:5 by weight) composite, which exhibits high-potential (up to 5 V vs. Li+/Li) and long-period (month-level) anti-overcharge performance. It is found that the additive does not hurt the electrochemical cycling performance under normal operational conditions. This novel safety strategy is simple and flexible, which may open a new window to develop safer LIBs systems. [Copyright &y& Elsevier]

Highlights: [•] A one-step sol-gel route with resorcinol-formaldehyde resin is designed to synthesis LiNi0.5Mn1.5O4. [•] Fd-3m phase delivers an excellent high rate performance and stable cycling retention. [•] A double “w”-shape R-V curve is a potential tool to indicate structure transition. [Copyright &y& Elsevier]

Highlights: [•] A unique bowl-like hollow spherical Co3O4 structure is prepared through a simple, low-cost and mass-yield method. [•] Such a bowl-like hollow Co3O4 microsphere demonstrates extraordinary rate and cycling performance for Li-storage. [•] The sodium-storage behavior of Co3O4 is investigated for the first time. [ABSTRACT FROM AUTHOR]

Abstract: A plate-like carbon-coated Li3V2(PO4)3 (LVP/C) powder composed of nanoplates was synthesized by a hydrothermal route. The structure and electrochemical properties of the LVP/C are characterized by X-ray diffraction, scanning and transmission electron microscopy, and galvanostatic charge–discharge cycling. This LVP/C electrode exhibits good rate performance at room temperature with a specific capacity of 113.8 and 128.8mAhg−1 at 6C rate in the voltage range of 3.0–4.3V and 3.0–4.8V, respectively. The sample also shows good cycling performance with 91.4% and 85% of capacity retention after 200 cycles at 1C rate. Even at −20°C, the plate-like LVP/C delivers a stable cycling performance with a specific capacity of 120.7mAhg−1, being 95.3% of the capacity at room temperature, and after 80 cycles, the capacity retention is 97.2%. [Copyright &y& Elsevier]

Abstract: Micrometer Li1.05Mn1.95O4 has been synthesized by solid state reactions with the nano-Mn3O4 as a precursor. X-ray diffraction, scanning electron microscopy and laser particle sizer are employed to investigate the structures, morphologies and particle size distributions of the powder. The micrometer Li1.05Mn1.95O4 exhibits good rate performance at room temperature with a specific capacity of 98.4mAhg−1 at 5C. The Li1.05Mn1.95O4/Li half cell also shows good cycling performance at elevated temperature with 90.5% of its initial capacity retained after 100 cycles at 1C. At −20°C, the Li1.05Mn1.95O4 delivers a stable cycling performance with a specific capacity of 84.5mAhg−1, being 84.1% of the capacity at room temperature. The cyclic voltammetry (CV) and rate performance measurements illustrate an increasing polarization with decreasing the temperature. In addition, the diffusion coefficients of lithium ions in Li1.05Mn1.95O4 at various temperatures (25, 0, −10 and −20°C) are determined to be in the magnitude of 10−10 to 10−12 cm2 s−1 by cyclic voltammetry (CV) method. [Copyright &y& Elsevier]

Abstract: Cobalt alkoxide suspension is obtained by heating a mixed polyalcohol solution of cobalt acetate in an oil bath at 170°C. Thermogravimetric analysis is adopted to determine the chemical formula of the alkoxide powder in the suspension. With the suspension precursors, CoO/Co composite thin films are fabricated by electrostatic spray deposition and subsequent heat treatment in nitrogen. They are characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. Electron energy loss spectroscopy mapping is applied to determine the lateral two-dimensional chemical distribution of metallic Co in the nanocomposites. The thin film can deliver a high reversible capacity of 1182.1mAhg−1 at 70th cycle and retain 69.5% of the initial capacity at 10C. The in situ production of metallic cobalt and the unique hollow structure of the particles can account for the good electrochemical performance. [Copyright &y& Elsevier]

Abstract: Among various anode materials for lithium ion batteries, MnO has attracted a wide-spread attention for its low charge potential (1.0V vs. Li/Li+) and high theoretical capacity (755mAhg−1). In this paper, we propose a facile way to synthesize carbon-coated nano-MnO powders (MnO/C). Mn3O4 nanoparticles with a particle size of about 20nm are firstly obtained in an alcoholysis process of manganese acetate tetrahydrate with diethylene glycol as the solvent. Then glucose is used as both a carbon source and a reducing agent to prepare MnO/C nanospheres. From the mixtures of Mn3O4 and glucose, nano-MnO/C composites with a carbon content up to 18.1wt% are obtained. X-ray diffraction and transmission electron microscopy are used to analyze the structures of the nano-Mn3O4 and nano-MnO/C composites. The electrochemical properties of the nano-MnO/C composites are also characterized. The electrode made from 10.7wt%-carbon-coated MnO/C shows very stable cycling performance with a high reversible capacity of 939.3mAhg−1 after 30 cycles at 0.1C. This electrode also shows favorable rate performance with specific capacities of 726.7, 686.8, 633.0 and 587.9mAhg−1 at 1C, 2C, 5C and 10C, respectively. [Copyright &y& Elsevier]

Abstract: Transition metal oxides represent a new type of anode materials for lithium-ion batteries. Due to their high capacity (usually above 700mAhg−1) and excellent cycleability, they have attracted much attention in recent years. Regarding the electrochemical reaction mechanism for this type of electrode, the conversion reaction mechanism proposed by Tarascon and co-workers is widely accepted, i.e. MO x +2xLi⇆M+ xLi2O. Nevertheless, in our recent explorations, we have found some new phenomena which may help us to further understand the electrode reaction mechanism, and even pose a necessity to modify the current conversion reaction mechanism. These new phenomena can be summarized as electrochemical milling, capacity rise and no-metal-formation effects. [Copyright &y& Elsevier]

• The TEP and nano-TiO 2 particles promote the chain segment motion with segment in a PEG matrix. • An electric double layer enhances the lithium ion migration. • The TEP alleviated the force between EO and Li+, constructing a fast ion conducting channel. • The uniformity of lithium deposition is performed by the relatively ordered array transmission channel. • A dual acceleration conduction effect of Li by the nano-TiO 2 and TEP is reported. In recent years, the pursuit of high electrochemical stability and safety are considered as the newly growing and leading trend of next-generation lithium-ion batteries (LIB). The gelation of polymer electrolytes(GPEs) is the most direct and effective way to improve electrochemical performance. Herein, a novel composited polyethylene glycol (PEG) electrolyte is reported with a dual acceleration conduction effect of Li+ by the nano-TiO 2 and triethyl phosphate (TEP). The negative ZETA potential of nano-TiO 2 /PEG internal interface promoted the dissociation of lithium salt by the unstable adsorption in diffusion layer, which enhanced the lithium ion migration and promoted the uniformity of lithium deposition. The flame retardant TEP improved safety performance, adjusted the affinity between EO and Li+, which bestowed it a high discharge 125.7mAh/g at 0.2C, with a low average capacity decay rate of 0.08% per cycle. The well-designed PEG-TEP-TiO 2 GPEs showed wide electrochemical window, stable Li+ stripping/plating, smaller voltage polarizations and excellent cycling performance. The new understanding of composite electrolytes provides a powerful avenue for facilitating the gelation-solid-state lithium ion batteries. [ABSTRACT FROM AUTHOR]

This review focuses on biomass-derived nanostructured carbons and their composites for lithium ion batteries, supercapacitors and polymer electrolyte membrane fuel cells. Electrochemical energy devices including batteries, supercapacitors and fuel cells are reliable and practical technologies in which carbon-based electrode materials play critical roles in enhancing performance. Because of this, the source and synthesis of these carbon-based materials have been extensively explored and developed. And of the various carbon-based materials, biomass-derived carbon materials and corresponding composites have been recognized to be capable of delivering high capacities, enhanced rate performances and prolonged cycling stabilities in both lithium-ion batteries and supercapacitors as partially induced through a combination of favorable pore structures and heteroatom-doping. In addition, biomass-derived carbon materials can provide significantly enhanced activity and stability for cathode oxygen reduction reactions if used as catalyst support materials in polymer electrolyte membrane fuel cells. Based on this, this review will provide a comprehensive assessment as well as critical analysis and systematic comparison of biomass-derived carbon materials and corresponding composites as electrode materials in various electrochemical energy devices based on recent progresses in research and development. In addition, related technical challenges are analyzed and possible research directions are proposed to further development for practical application. [ABSTRACT FROM AUTHOR]