Search

Rechargeable aluminum-ion batteries have been researched extensively due to their attractive features, such as the abundant aluminum resources and high capacity resulting from the three-electron redox properties. Herein, a porous carbon supported SnO2 nanocomposite is reported as a cathode material for AIBs. The resultant cell exhibits a high discharge specific capacity of 370 mA h g−1 (with an initial value of 434 mA h g−1) at 50 mA g−1. In the cycling performance, the cell retains a stabilized discharge capacity of 72 mA h g−1 after 20 000 cycles with a coulombic efficiency of ∼100% under an ultrahigh current density of 2 A g−1. Owing to the well-defined nanostructure, side reactions and pulverization of active particles can be prevented. The results indicate that the SnO2/C nanocomposite is a favorable cathode material for AIBs and opens up a new opportunity for the design of high-performance AIBs.

Recently, many exciting achievements have been made in improving the cycling performance of SnO2-based electrode. However, the low initial Coulombic efficiency of SnO2-based electrode caused by the formation of solid electrolyte interphase and some of the irreversible formation of Li2O in SnO2 structure still remains unresolved. Here this work reports a primary-cell process to prelithiate the SnO2-based composites to compensate the irreversible loss during the first cycle. The primary-cell-prelithiated SnO2@C composites performs a high initial Coulombic efficiency from 92.7% to >100% with the prelithiation time extends. Even after 600 cycles, the prelithiated (24 h) SnO2@C composites show a high capacity retention of 95% (848 mAh g−1) at a current density of 0.5 A g−1.

Low volumetric-energy-density caused by low tap density of nanomaterial seriously restricts the application of nanomaterial in lithium-ion batteries. Here, to solve this problem, micron-sized Fe2O3 secondary particles (MFSPs) with high tap density (2.8 g cm−3) are synthesized via a facile way. As a result, ultrahigh volumetric-energy-density of 1490 mA h cm−3 is obtained after 100 cycles at C/2 (∼500 mA g−1). Densely packed structure of MFSPs exhibits well structural stability and electrical conductivity. For the high areal mass loading of 4.02 mg cm−2, an areal capacity about 3 mA h cm−2 is achieved.

Lithium–sulfur batteries hold great promise for serving as next generation high energy density batteries. However, the shuttle of polysulfide induces rapid poor cycling stability of lithium–sulfur cells. Using an interlayer inserted between the sulfur cathode and the separator to capture these soluble intermediates can diminish this effect effectively. Herein, a ultrathin TiO2 nanotubes/graphene oxide (TiO2 NTs/GO) hybrid membrane (the thickness is less than 10 μm) used as an interlayer in lithium sulfur battery can effectively improve the cycle performance by trapping the soluble polysulfides. As a result, the sulfur cathode with TiO2 NTs/GO hybrid membrane as interlayer exhibits an initial discharge capacity of 1431.5 mA h g−1 and maintains the reversible capacity of 845.8 mA h g−1 at 0.1C after 100 cycles.

Tin dioxide (SnO2) is a promising anode material for lithium-ion batteries owing to its large theoretical capacity (1494 mA h g−1). However, its practical application is hindered by these problems: the low conductivity, which restricts rate performance of the electrode, and the drastic volume change (400%). In this study, we designed a novel polyacrylamide/SnO2 nanocrystals/graphene gel (PAAm@SnO2NC@GG) structure, in which SnO2 nanocrystals anchored in three-dimensional graphene gel network and the polyacrylamide layers could effectively prevent the agglomeration of SnO2 nanocrystals, presenting excellent cyclability and rate performance. A capacity retention of over 90% after 300 cycles of 376 mA h g−1 was achieved at a current density of 5 A g−1. In addition, a stable capacity of about 989 mA h g−1 at lower current density of 0.2 A g−1 was achieved.

To meet the requirements for the quick charge for the hybrid electric vehicles (HEVs) or plug-in hybrid electric vehicles (PHEVs), better rate capability is urgently needed for the lithium ion batteries (LIBs). Here in our work, a new anode with excellent rate capability is developed. In this anode, nanoporous iron oxide nanoparticles coated with carbon (designated as Fe 2 O 3 @C NPs) are homogeneous distributed in carbon nanofibers (CNFs), which can be designated as Fe 2 O 3 @C CNFs. The CNF constrains the nanoporous Fe 2 O 3 @C NPs along the longitudinal direction and the fibers are cross-linked, establishing a three dimensional (3D) stable electric conductive network. The nanoporous Fe 2 O 3 @C NPs exposed on the surface of CNFs provide more active sites for electrode reactions. The thin carbon shell around the Fe 2 O 3 NPs gives the additional protection and improves the conductive connection between the nanofibers, leading to an integral conductive network which links all the Fe 2 O 3 @C NPs. The Fe 2 O 3 @C CNFs structure exhibits good capacity retention and excellent rate capacity at high current density.

We report on the synthesis of heterotelechelic α,ω-dye-labeled polystyrene and poly(methyl methacrylate) via a combination of site-specific atom transfer radical polymerization (ATRP) and click chemistry. By using the advantages of the living polymerization characteristics and a robust coupling efficiency, the Forster/fluorescence resonance energy transfer (FRET) pairs (i.e., carbazolyl and anthryl) were dictated to be at the near-stoichiometric chain ends. The distribution of the end-to-end distance was well described by the energy transfer response of the fluorescent groups between chain ends, which is in reasonable agreement with Gaussian statistics. The synthetic approach described here provides an opportunity to prepare polymeric materials with customized responsive elements and in-depth insight into the statistical scaling dimension of polymers.

A new type of chain transfer agent used in reversible addition fragmentation chain transfer (RAFT) polymerization named 9-anthracenylmethyl (4-cyano-4-(N-carbazylcarbodithioate) pentanoate) (ACCP) was synthesized with a total yield over 75% by the incorporation of both fluorescent donor and acceptor chromophores. Polymerization of heterotelechelic α,ω end-labeled dye-functionalized polystyrene (PS), poly(methyl methacrylate) (PMMA), and poly(n-butyl methacrylate) (PBMA) with adjustable molecular weights and narrow polydispersity could be conducted by a one-pot procedure through RAFT polymerization with this bischromophore chain transfer agent. The polymerizations demonstrated “living” controlled characteristics. By taking advantage of the characteristic fluorescence resonance energy transfer (FRET) response between the polymer chain terminals, the variation of chain dimensions in solution from the dilute region to the semidilute region can be monitored by changes in the ratio of the fluorescence intensities of the carbazolyl group to the anthryl group, which lends itself to potential applications in characterizing chain dimensions in solutions for thermodynamic or dynamic studies. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2413–2420

Tin dioxide (SnO2) is an attractive material for anodes in energy storage devices, because it has four times the theoretical capacity of the prevalent anode material (graphite). The main obstacle hampers SnO2 from practical application is the pulverization problem caused by drastic volume change (∼300%) during lithium-ion insertion or extraction, which would lead to the loss of electrical conductivity, unstable solid-electrolyte interphase (SEI) formation and consequently severe capacity fading in the cycling. Here, we anchored the SnO2 nanocrystals into three dimensional graphene gel network to tackle this problem. As a result of the three dimensional (3-D) architecture, the huge volume change during cycling was tolerated by the large free space in this 3-D construction, resulting in a high capacity of 1090 mAh g−1 even after 200 cycles. What's more, at a higher current density 5 A g−1, a reversible capacity of about 491 mAh g−1 was achieved with this electrode.

Tin dioxide (SnO 2 ) is one of the most promising anode materials for the next generation Li-ion batteries due to its high capacity. To solve the problems caused by the large volume change (over 300%) and the aggregation of the tin particles formed during cycling, nano SnO 2 /C composites are proved to be ideal anode materials for high performance Li-ion batteries. However, it is still a challenge to disperse ultrasmall ( 2 nanoparticles with uniform size in carbon matrix. Here, we report a facile hydrothermal way to get such optimized nano SnO 2 /C composite, in which well dispersed ultrasmall SnO 2 nanocrystals (3∼5 nm) are embedded in a conductive carbon matrix. With this anode, we demonstrate a high stable capacity of 928 mAh g −1 based on the total mass of the composite at a current density of 500 mA g −1 . At high current density of 2 A g −1 , this composite anode shows a capacity of 853 mAh g −1 in the first charge, in such high current density, we can even get a capacity retention of more than 91% (779 mAh g −1 ) after 1000 cycles.

Tin dioxide (SnO

A composite of nanoporous iron oxide (Fe2O3) nanoparticles coated with a thin layer of carbon (designated as nanoporous Fe2O3@C) is synthesized using a convenient one-pot solvothermal method. Although the thickness of the carbon framework is only 6 nm on average, which is very small compared to the size of Fe2O3 nanoparticles, the carbon framework significantly enhances the electrochemical performance of nanoporous Fe2O3@C composites when they are used as an anode material for lithium-ion batteries. Thanks partly to the relatively low carbon content of 6.7 wt%, the nanoporous Fe2O3@C anodes exhibit a high reversible capacity of 767 mA h g−1 after 100 cycles at a current density of 500 mA g−1 and 545 mA h g−1 even at a higher current density of 2 A g−1. In comparison to commercial Fe2O3 nanoparticles and bare nanoporous Fe2O3 nanoparticles, the nanoporous Fe2O3@C anodes show superior cycle life. The nanoporous structure offers void space for volume change of Fe2O3 nanoparticles, while the thin carbon framework improves the stability of structures and SEI (solid electrolyte interphase) films during the continuous intercalation/deintercalation processes of Li ions.

The dynamics of poly(n-butyl methacrylate) confined in porous anodic aluminum oxide (AAO) templates are investigated using differential scanning calorimetry (DSC) and fluorescence nonradiative energy transfer (NRET). Two glass transition temperatures (Tg,low and Tg,high) are obtained at higher infiltration temperatures via capillary force followed by slow cooling. Tg,low resembles the Tg of the bulk phase and represents the transition of the core layer. Tg,high represents the transition of the adsorbed layer in the confined polymer glass. The temperature threshold to form one or two glass transitions is determined by adjusting the infiltration temperatures and the pore diameters. It is shown that the adsorbed layer has increased interchain proximity relative to the bulk. In addition, the glass transition behavior is hypothesized to be mediated by the counterbalance of the size and interfacial effects in the confined space. The easily synthesized core–shell nanofibers with one glassy and one rubbery compon...