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Reasonable design for structure and composition of multi-component metal oxides is an effective and promising way to improve electrochemical performance of electrode materials. In this work, novel carnations-like Mn 3 O 4 @NiCo 2 O 4 @NiO hierarchical nanostructures are constructed by introducing CATB as structure-directing agents and adjusting hydrothermal reaction time. The perfect architecture maximizes the synergistic effect between components, providing more electrochemical reactive sites and promoting the diffusion and transfer of electrolyte ions. As a result, Mn 3 O 4 @NiCo 2 O 4 @NiO electrodes deliver an enhanced specific capacitance of 1905 F g−1 at 1 A g−1 and outstanding cyclic stability (92% of its initial capacitance is retained after 10000 cycles). Furthermore, ASC device which is assembled by the Mn 3 O 4 @NiCo 2 O 4 @NiO and activated carbon achieve excellent energy densities of 76.8 W h kg−1 at power densities of 800 W kg−1, proving the optimized Mn 3 O 4 @NiCo 2 O 4 @NiO is promising electrode material for supercapacitor. In addition, this work supplies helpful insights into rational design for structure and composition of multi-component metal oxides for enhancing electrochemical performance. [ABSTRACT FROM AUTHOR]

Abstract Rational design of modified separator is of great significance in effectively suppressing the shuttle of lithium polysulfides (LiPSs) and hence realizing fulfilling cycling performance of lithium-sulfur batteries (LSBs). In this paper, we developed a facile strategy to fabricate P-doped carbon coated CNT skeleton coupled with nickel phosphide (Ni 2 P) nanospheres (PCCNT@NPS), and then we employed the as-developed hybrid as a multifunctional modified interlayer onto PP separator (denoted as PCNPmPP) to face the challenge of LiPSs shuttling. The as-prepared hybrid provides abundant physical confinement and strong chemical adsorption for inhibiting polysulfides shuttling as well as efficient catalysis for accelerating LiPSs converting. As a result, the LSBs based on PCCNT@NPS modified PP separator have delivered a highly reversible cycling performance with high initial discharge capacity of 1067 mAh g−1 and low capacity decay rate of 0.077% per cycle within 500 cycles at 1 C. The promising results demonstrate that the PCCNT@NPS composite is capable of effectively inhibiting the diffusion and shuttle of LiPSs. This paper provides a novel thinking for the synthesis of multifunctional interlayer onto PP separator for advanced LSBs. [ABSTRACT FROM AUTHOR]

Abstract Novel hierarchically porous titanium-metal organic frameworks/nitrogen-doped graphene (Ti-MOFs/NG) nanocomposite derived from titanium-metal organic frameworks (Ti-MOFs) and the nitrogen-doped graphene (NG) has been originally synthesized successfully. Notably, the Ti-MOFs/NG nanocomposite has been for the first time investigated in detail, as oxygen reduction reaction (ORR) catalyst of cathodic materials for fuel cells. The results show that the Ti-MOFs/NG nanocomposite possesses excellent ORR performances, whether in alkaline or acidic medium, due to existences of the Ti 3 N 2-x , C 2 O 7 Ti 2.3 , H 2 Ti 5 O 11 , Ti and TiO active ORR segments. Specifically, the onset potential (E 0) and the Tafel slope value of the Ti-MOFs/NG nanocomposite are 1.14 V and 17.84 mV dec−1 in 0.1 M HClO 4 , respectively. Similarly, high ORR efficiency of the Ti-MOFs/NG nanocomposite also exhibit in alkaline medium. The relative current density can still keep 99.88% of the original value after 10800 s measurements in 0.1 M KOH. Additionally, small electrochemical impedance and excellent tolerance toward fuel molecules have been exhibited in both electrolytes. These ORR properties are superior to those of most of previously reported materials derived from other MOFs, in both alkaline and acidic media. Thus, the Ti-MOFs/NG nanocomposite is as a novel promising candidate for ORR catalyst to solve the main problems of sluggish reaction kinetics of the ORR, high cost of precious metal catalysts and low durability of the traditional catalysts, applied to fuel cells, metal-air batteries and further to water splitting in energy conversion and storage devices. [ABSTRACT FROM AUTHOR]

Cobalt nanofibers @ Ni 3 S 2 nanosheets (Co@Ni 3 S 2 ) composites with high surface area (241.67 m 2 /g) were successfully synthesized via a chemical conversion route. The special nanostructure afforded sufficient space for the volume change, ensured efficient electrolyte penetration, increased contact area between electrolyte and active material during discharge–charge process. Moreover, the existence of the cobalt nanofibers with high conductivity provided a possibility for the rapid transportation of the electrons and lithium ions. The composite electrodes presented a reversible discharge capacity of 531 mAh/g with a good cyclic stability. This research perhaps inspired the designing of high performance electrode materials with a novel structure for high performance energy storage devices. [ABSTRACT FROM AUTHOR]

Metal oxide nanoparticles as the electrochemically active second phase were incorporated into the paper-like flexible graphene-based hybrid electrodes. Its size and dispersion are crucial factors for determining the rate capability and cycling stability of the flexible hybrid paper electrode. Herein, we employ in-situ formed ultrafine monodisperse TiO 2 quantum dots (QDs, ∼4.0 nm) as the electrochemically active second phase, which are uniformly incorporated into the flexible hybrid paper via a simple mixed solvothermal reaction together with a vacuum filtration, aiming at achieving a high-rate and long-cycle flexible TiO 2 -based anode in lithium ion batteries (LIBs). By combining the advantages of both ultrafine TiO 2 -QDs and three-dimensional (3D) conductive networks, the as-fabricated TiO 2 -QDs-reduced graphene oxide (TiO 2 -QDs-RGO) hybrid paper electrode shows high reversible capacity of 201 mA h g −1 after 100 cycles at 0.1 A g −1 and superior rate capability as well as long cycle life of 1500 cycles with ∼80.6% capacity retention at 2.0 A g −1 . Detailed electrochemical analysis shows that the improved capability and cyclability of the hybrid paper electrode results from the integrated intercalation-based and interfacial lithium storage behaviors as well as the 3D fast electron/ion transfer of materials, which is ascribed to the ultra-small size of TiO 2 -QDs and the 3D self-standing conductive networks of the hybrid paper electrode. The results demonstrate the distinct advantages of our material design strategy, and also might pave the way for further studies of other flexible metal oxide/graphene hybrid paper electrodes for fast and long-life flexible anodes in LIBs. [ABSTRACT FROM AUTHOR]

A novel type of porous TiO 2 nanobelts anchored with Sn 3 O 4 nanosheets (TiO 2 nanobelts @Sn 3 O 4 nanosheets) core-shell composites were developed via two-step hydrothermal methods. The structure, morphology, formation mechanism and electrochemical performance of the porous TiO 2 nanobelts coated with mixed transition-metal oxides Sn 3 O 4 nanosheets core-shell composites were researched. The results illustrated that the Sn 3 O 4 nanosheets were uniformly anchored on the surface of the porous TiO 2 nanobelts, which were almost perpendicular to the porous TiO 2 nanobelts. The composites as anode materials exhibited more remarkable electrochemical performances than the Sn 3 O 4 nanosheet and the porous TiO 2 nanobelts, in terms of the cycling performance and rate capability. The initial discharge capacity was 1513.7 mAh/g and the reversible capacity was 659 mAh/g after 50 cycles. This study perhaps inspired the designing of other transition metal oxide-based anode materials with desirable electrochemical performance for applications of lithium ion batteries. [ABSTRACT FROM AUTHOR]

Hybrid hollow urchin-like cobalt and copper silicate constructed by nanotubes encapsulated in graphene nanosheets composites were successfully prepared using graphene oxide as carrier and silica spheres as template, which were done through a well-known Stȍber process and a hydrothermal method. In fact, the synthesis of hybrid urchin-like silicate constructed by nanotubes through onestep hydrothermal reaction has rarely been reported.The electrochemical performances of the composites as lithium-ion battery anode materials were studiedfor the first time. As novel anode materials of Li-ion batteries, the special hollow urchin-like structure not only could facilitate the Li + diffusion and electron transport but alsocouldaccommodate the volume variation during the conversion reactions. In addition, the introduction of graphene can make the electrical conductivity better. Graphene wrapped hollow urchin-like silicate compositespossesses superior electrochemical cycling properties. The first discharge capacity is1955.2mAh/g with a current density of 300 mA/g. The unique well-designed configuration presents a beneficial method to synthesize efficient and high performance electrode materials for advanced power applications. [ABSTRACT FROM AUTHOR]

Novel a - MoO 3 nanorods coated with SnS 2 nanosheets core-shell nanorod composite has been synthesized via two hydrothermal routes. More importantly, as the anode materials for lithium ion batteries, the MoO 3 @SnS 2 core-shell nanorod composite has not been investigated in detail. The one-dimensional core-shell nanorod composite has high surface area, which could offer larger contact area for material and electrolyte. In addition, there are large enough inner spaces between the SnS 2 nanosheets, which provides an efficient transport of electrons and ions. In addition, the core-shell nanostructure could accommodate the volume changes caused by the charge/discharge reaction and could avoid the agglomerations and pulverization of anode materials.As anode materials for LIBs, the as-prepared MoO 3 @SnS 2 core-shell nanorod composite displayed 1663.2mAh/g discharge capacity in the first cycle at the current of 60mA/g. After 100 cycles, the remained capacity is 568.2mAh/g, which is both higher than that of a-MoO 3 and SnS 2 . Considering the excellent electrochemical performance with high capacity and good cycling stability, the as-prepared the MoO 3 @SnS 2 core-shell nanorod composite has the potential to be the next generation anode materials for lithium ion batteries. [ABSTRACT FROM AUTHOR]

In this work, the soft-template hydrothermal method is firstly applied to synthesize nanocrystal CuWO 4 cubes for the electrode materials in in electrochemical charge storage application. The structures and morphologies of as-obtained materials are characterized via X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The effects of the soft-template (P123) and surfactant (Hexamethylenetetramine) also are verified by the electrochemistry test including CV, GCD, EIS. As a result, the CuWO 4 -PH (synthesis with the assistance of P123 and Hexamethylenetetramine) shows a excellent specific capacitance (C sp ) of 302.40 mAh g −1 at the current density of 1 A g −1 and a good rate capability (60.7% retension rate of original Csp even at 10 A g −1 ), as well as cycle life (82.1% retention rate of original C sp after 2000 cycles). These results reveal that our obtained CuWO 4 -PH could be a promissing electrode material. [ABSTRACT FROM AUTHOR]

Potassium hydroxide (KOH) activated Super P (Ksp) was adopted to prepare Ksp/S composite by chitosan assisted chemical synthesis approach. The Ksp/S was further heat treated at 159 °C and then coated by polyaniline (PANI) to fabricate Ksp/S-159 and Ksp/S-159/PANI composites, respectively. The heat treated binary sulfur/carbon and PANI coated ternary sulfur complex showed enhanced cycle performance and rate capability. However, the electrochemical behavior of Ksp/S-159 and Ksp/S-159/PANI can be greatly affected by the discharge current. The Ksp/S-159/PANI composite delivers an initial discharge capacity of 1202.3 mAh g −1 and keeps 954 mAh g −1 after 100cycles at 0.5 mA cm −2 (0.31C). The Ksp/S-159 presented a maximum capacity up to 892.5 mA h g −1 at 2 ma cm −2 (1.26C) and retained about 409.2 mA h g −1 after 500 cycles. The PANI coated ternary sulfur complex shows good electrochemical performance at low discharge current while the heat treated sulfur/carbon shows good rate capability at high discharge current. The different electrochemical behavior is fully discussed to illustrate the complex Li-S discharging process. [ABSTRACT FROM AUTHOR]

Hydriodic acid and self-assembly approach are used to fabricate graphene wrapped sulfur composite. The self-assembly process of the relative “large” graphene sheet and “small” sulfur is quite controllable, and the sulfur particles are completely enfolded by RGO sheets with a unique stacked structure .The RGO/S composite with 80 wt.% sulfur shows an initial discharge capacity of 865.1 mAh g −1 at 0.5 mA/cm 2 . A high specific capacity of 720 mAh g −1 with a coulombic efficiency of 95% is achieved after 50 cycles of charge/discharge. The material also delivered a capacity of more than 580 mAh g −1 at 2 mA/cm 2 and can be recovered to 736 mAh g −1 when the rate is returned to 0.2 mA/cm 2 , representing a promising cathode material for high current discharge lithium-sulfur batteries. [ABSTRACT FROM AUTHOR]

Hollow Zn 2 SnO 4 boxes@C/graphene ternary composites with a three-dimensional triple buffering structure are prepared by two hydrothermal processes followed by a calcined process. The structure, morphology and electrochemical properties of the ternary composites were investigated by means of XRD, FTIR, Raman, BET, BJH, SEM, TEM, and electrochemical measurements. The hollow Zn 2 SnO 4 boxes are coated with carbon layer and then supported by graphene sheets to form a 3D carbon conductive network. Compared with the hollow Zn 2 SnO 4 boxes@graphene binary composites, the hollow Zn 2 SnO 4 boxes@C binary composites, the hollow Zn 2 SnO 4 boxes and the solid Zn 2 SnO 4 cubes, the hollow Zn 2 SnO 4 boxes@C/graphene ternary composites show an enhanced electrochemical performance (726.9 mAh g −1 at a current density of 300 mA g −1 after 50 cycles) and high rate capability. With the unique structure design, this kind of composites with excellent electrochemical properties can be a promising anode material for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Abstract: The graphene wrapped hollow Zn2SnO4 boxes are fabricated via the electrostatic interaction. The flexible graphene wrapping layers, as a physical buffering matrix to reinforce the hollow structure, prevent interparticle agglomeration and improve the electronic conductivity of the hollow Zn2SnO4 boxes. Compared with our previous studies, graphene wrapping Zn2SnO4 boxes show an enhanced electrochemical performance (678.2 mAhg−1 after 45 cycles) and high rate capability. With rational and delicate design, this kind of composites may be the potential anode materials for lithium-ion batteries. [Copyright &y& Elsevier]

Abstract: In this research, a manganese dioxide (MnO2) nanowires/chitosan-modified gold (Au) electrode was successfully fabricated for amperometric determination of dopamine (DA) at a very low working potential (0.00V vs. SCE). The electrochemical properties of the modified Au electrode were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The detection scheme was proposed to involve two major reactions: the chemical oxidation of DA to o-dopaminoquinone by MnO2 nanowires, and then the electro-reduction of o-dopaminoquinone to DA at a low working potential (0.00V vs. SCE), resulting in a distinct reduction response current. The modified Au electrode displays good amperometric response to DA in a wide concentration range 0.10μM to 1.10mM. The fabrication of MnO2 nanowires/chitosan-modified Au electrode is simple and highly reproducible (RSD=3.8%, n =5). It exhibits excellent analytical performance in terms of low working potential (0.00V vs. SCE), long shelf-life (90% of its initial response after 1-month storage) and high repeatability (RSD=2.2%, n =5). Finally, it was applied to determine DA in real samples directly with high accuracy (99%) and good recovery (99.7–103%), confirming its promising application in routine DA analysis. [Copyright &y& Elsevier]

Abstract: In this paper, a sensitive graphite/poly(methyl methacrylate) (PMMA) composite electrode was firstly applied to the determination of o-sec-butylphenol (osBP). This polymer carbon paste electrode (CPE) effectively improved the soft surface of traditional CPE, and enhanced the sensitivity and reproducibility. Factors influencing detection processes were optimized and kinetic parameters were calculated. Under the optimal conditions, the amperometric current density was linear with the concentration of osBP in the range from 2.50×10−7 to 3.55×10−5 molL−1 and the detection limit was 3.48×10−8 molL−1. The proposed method was successfully used to determine osBP in greengrocery samples and satisfactory results were obtained. [Copyright &y& Elsevier]

Abstract: The corrosion behaviors of perovskite La0.8Sr0.2Co0.3Fe0.7O3−δ (LSCF) in the sodium tetrasulfide melt have been studied to demonstrate its possibility to be used as a coating material for the positive current collector in the sodium sulfur battery (Na/S). The electrochemical techniques including potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) are applied in the study. The results demonstrate that the corrosion process of the LSCF in sodium tetrasulfide melt is activation controlled. The corrosion current density of the LSCF is approximate 10 times smaller than that of the 316L stainless steel. Two compact corrosion layers which may act as a stable barrier retarding the corrosion process have formed on the surface of LSCF after immersed for 130 days. The promising results suggest that LSCF exhibits high corrosion resistance against molten sodium tetrasulfide and may be an appropriate candidate coating material for the positive current collector in Na/S battery. [Copyright &y& Elsevier]

A composite gel polymer electrolyte (CGPE) based on cross-linked poly (ethylene oxide) with excellent comprehensive properties for the application of lithium metal battery was prepared by UV curing. The cubic Li 6.7 La 3 Zr 1.7 Ta 0.15 Nb 0.15 O 12 (TN) micron sized powder was used as an enhancer. Among them, the CGPE membrane with 10% TN filler has the best performance. While it has excellent mechanical properties and thermal stability, the corresponding room temperature ionic conductivity is as high as 3.5 mS cm−2, the lithium ion migration number is 0.55, the electrochemical stability window is about 5.5 V, and shows excellent stability to lithium metal. At the same time, the lithium metal battery based on the electrolyte film has good rate performance and cycle stability (143.6 mA h g−1 with capacity retention of 91.6% after 175 cycle at 0.2 C and 91.8% capacity retention after 100 cycle at 1.0 C), indicating it has practical application prospect. [ABSTRACT FROM AUTHOR]

Transition metal oxides are expected to replace commercial graphite for the next generation of secondary battery anode materials. However, the capacity decreases rapidly due to poor conductivity and volume expansion during operation. In this study, we first designed a yolk-shell structured ZnCo 2 O 4 sphere, and then combined it with reduced graphene oxide through an electrostatic interaction process. The prepared ZnCo 2 O 4 /RGO showed enhanced lithium/sodium storage performance. Specifically, it can provide 997.2 mA h g−1 (for LIBs, 500 cycles) and 280 mA h g−1 (for SIBs,1000 cycles) reversible capacities at 1.0 A g−1 current density, respectively. These superior properties are derived from their unique structure. On the one hand, the gap between the yolk and shells not only provides a shorter Li+/Na+ diffusion distance, but also the electrolyte can be in sufficient contact with the anode material to induce a rapid surface reaction; on the other hand, the introduction of graphene can effectively buffer the large volume expansion of the cycle and maintain the structural integrity of the electrode material. [ABSTRACT FROM AUTHOR]

A facial and efficient process for the synthesis of porous Zn x Co 3-x O 4 hollow nanoboxes using zeolitic imidazolate frameworks as precursors has been demonstrated in this study, the as-prepared electrodes are applied for both LIBs and SIBs. The porous structure and hollow interspace can not only provide valuable channels and voids for lithium/sodium ion transfer and storage, but also buffer the stress/strain caused by volume changes. Besides, the enhanced electrical conductivity can effectively improve the reaction kinetics by synergistic effect of the binary metal oxides, as studied by density functional theory (DFT) calculations and storage mechanism studies. For lithium-ion batteries, the electrode exhibits an ultrahigh reversible capacity of 1141.7 mAh g−1, with an initial coulombic efficiency of 95.6%, and an ultralong life up to 800 cycles at 500 mA g−1. Even at a high current of 3.0 A g−1, a superior capacity of 484 mAh g−1 can be achieved. When using for sodium-ion battery anode, the reversible capacity is remained at 310 mAh g−1 after 100 cycles at 200 mA g−1, with a capacity retention of 90.4%. The electrode materials show long-term cycle stability and excellent rate capability, which gives a bright prospect for energy storage devices. • The unique structure can accelerate the transportation of ions. • The synergistic effect shows enhanced electrical conductivities and ion diffusions. • The general phenomenon of the capacities rise is discussed in detail. • The electronic structures of Zn/Co oxides were studied by density functional theory (DFT) calculations. [ABSTRACT FROM AUTHOR]

A novel type of hollow nitrogen-doped carbon@Bi 12 SiO 20 @nitrogen-doped graphene (H-NC@BSO@NG) nanocomposite was originally synthesized via emulsion polymerization, solvothermal process and calcination method. As a novel catalyst of cathodic oxygen reduction reaction (ORR), H-NC@BSO@NG is in detail reported for the first time. Study results have illustrated that hollow dual core-shell nanostructure with hierarchical porosity has been formed perfectly. Nitrogen-carbon layer (NC) as the hollow inner core and nitrogen-doped graphene (NG) as the outer layer can together act as both the catalysts themselves and the strong carriers of the Bi 12 SiO 20 (BSO) catalyst, which to some extent avoid the collapse and exfoliation of the intermediate Bi 12 SiO 20 in ORR process. And this hollow dual core-shell nanostructure can be in favor of formation of abundant bismuth-carbon/nitrogen ORR site and solve problem of poor electrical conductivity of Bi 12 SiO 20. The H-NC@BSO@NG nanocomposite exhibits good activity, well immunity to methanol crossover, and high stability. Its onset potential can reach 1.05 V. Its limiting current density can reach 6.29 mA cm−2 in basic electrolyte. Its relative current value can remain 91.39% of its initial value after 16000 s test. Our study perhaps inspire a novel design to synthesize hollow dual core-shell nanocomposite for the cathodic catalyst of fuel cell, air batteries, electrode nanomaterials and other purposes. Image 1 [ABSTRACT FROM AUTHOR]

Well-designed novel dual core-shell g-C 3 N 4 @Fe/Sr@g-C 3 N 4 nanosphere (FSCN-NS) is originally reported in detail as high efficiency of oxygen reduction reaction (ORR) electrocatalyst in both acidic and alkaline media for fuel cell. The g-C 3 N 4 as the catalyst carrier plays a critical role in facilitating the formation of the hierarchically porous architecture with large numbers of Fe 3 C, FeN x (x = 1–3), SrCN 2 and SrC 2 active ORR segments. Furthermore, g-C 3 N 4 as catalyst protector has a stable supporting effect against chemical corrosion, ensuring stability and durability of the as synthesized FSCN-NS for ORR in fuel cell cathode. Additionally, the introduction of Sr can produce metal-nitrogen-carbon bonds to provide active ORR sites, contributes to the formation of the hierarchically porous nanostructure. Thus, FSCN-NS exhibits high ORR activity with the onset potentials of 1.06 V and 1.08 V in alkaline and acidic media, respectively. Notably, half-wave potential, limiting current density, methanol tolerance and durability are all better than that of commercial 20% Pt/C catalyst and most of previously reported materials derived from other metal-C/N nanostructure. Thus, FSCN-NS is as promising cheap candidate to solve the main problems of sluggish reaction kinetics of the ORR, high cost and low durability for fuel cells and metal-air batteries in energy conversion and storage devices. [ABSTRACT FROM AUTHOR]

In this paper, phosphorus-doped porous carbon was obtained via a simple method with leaves as raw materials, and its broad application prospects in sodium-ion and lithium-ion battery were proved. The effect of different mass ratios on microstructure and properties were investigated. Phosphorus-doped porous carbon has high specific surface area and pore volume, which is favorable for contact with electrolyte and transportation of electron/ion. Meanwhile, doping of phosphorus increases layer spacing of carbon lattice and enhances adsorption of sodium ion, which are more conducive to the storage of sodium ions. Based on above advantages, PC-3 has stable and fast sodium-ion and lithium-ion storage performance with capacity of 310.4 mAh g−1 for sodium-ion battery and 723.4 mAh g−1 for lithium-ion battery after 200 cycles. Furthermore, carbonization temperature of this method is lower than other reports, saving energy and having better practical value. [ABSTRACT FROM AUTHOR]

• Few-layer Ti 3 C 2 is used to provide additional capacity. • The new voltage platform exhibits capacitive characteristics and continuously provides capacity under large rates and long cycles. • The initial Coulombic efficiency is greatly improved to 94.28%. LRMX3 discharges 158.3 mAh g-1 at 5 C and maintains 87.30% capacity at 5 C for 300 cycles. Li-rich Mn-based [xLi 2 MnO 3 ·(1-x)LiMO 2 ] (LR) cathodes are low cost and have high energy density, indicating high commercialization potential. However, the low initial coulombic efficiency, poor rate performance, and inferior cycling durability of LR cathodes confer difficulty in such commercialization. Herein, we proposed the use of a few-layer MXene (Ti 3 C 2) to improve electrochemical performance. We found that the few-layer MXene can improve the conductivity and provide additional capacity at low voltage (2.25 V), thereby greatly increasing the initial coulombic efficiency, rate, and cycle performance. The additional capacity may have originated from an interface space-charge storage with capacitive properties, that is, the storage and transport of ions and electrons at the interface of Ti 3 C 2 and LR particles. The modified sample exhibited an initial coulombic efficiency of 94.3 % and 158 mAh g–1 at 5C. Even after 300 cycles at 5C, it retained 87.3 % of its capacity. This novel strategy can serve as a reference for the modification of other electrode materials and can also expand the application of MXene in the field of batteries. [ABSTRACT FROM AUTHOR]

Ternary metal oxides based on nickel and cobalt are synthesized on Ni foam as the energy storage electrode using a nickel precursor-free hydrothermal reaction with incorporation of Mo, Fe, Cu, Zn, and Al, aiming to enhance the electrical conductivity and generate more Faradaic reactions via multiple transition states of metals. Ni foam is acted as the current collector and the Ni ion source to reduce precursor cost and enhance contact between electrocapacitive material and substrate. Benefit from the large surface area and vertically growing direction, the nickel cobalt copper oxide electrode shows the highest areal capacitance of 2.28 F cm -2   at 5 mA cm −2 among ternary metal oxide electrodes. An asymmetric supercapacitor based on the nickel cobalt copper oxide positive electrode and an activated carbon negative electrode also shows an areal capacitance of 917 mF cm -2   at 5 mA cm −2 , a potential window of 1.5 V, and an areal capacitance retention of 83.2% after 10,000 cycles charge/discharge process. Using the low-cost and effective nickel precursor-free synthesizing method to fabricate novel ternary metal oxides for asymmetric supercapacitors is successfully realized in this work. Further improvements based on this concept is worthy to investigate for achieving more efficient asymmetric supercapacitors for efficient energy storage. [ABSTRACT FROM AUTHOR]

Zero-dimensional quantum dots (QDs) are desired to enhance electrochemical response in energy storage. Here, we successfully synthesize well-dispersed and ultrafine TiO 2 -QDs, which are in situ embedded into the three-dimensional porous graphene-like networks (denoted as TiO 2 -QDs-3D GNs) via a simple low-temperature mixed solvothermal method, aiming at a fast electrochemistry with high-efficient electron and ion transport for lithium ion battery (LIB) anodes. By combining the advantages of the porous 3D GNs and ultrafine TiO 2 -QDs, the as-prepared TiO 2 -QDs-3D GNs hybrid electrode exhibits a high reversible capacity of 219 mA h g −1 after 100 cycles at 0.1 A g −1 , accompanied with an ultrahigh-rate capability of 121 mA h g −1 and a super-long lifespan of 3000 cycles with ∼82.0% capacity retention at 10 A g −1 . Detailed electrochemical analysis reveals that the superior rate capability and cycle performance are the main results of the integrated intercalation-based and interfacial lithium storage as well as the 3D fast electron/ion transfer of materials, which is attributed to the ultra-small size and high surface-to-volume ratio of TiO 2 -QDs as well as the 3D conducting networks of the integrated hybrid electrode. This study demonstrates the distinct advantages of our material design strategy, making it promising for the fast and ultralong-life anodes in LIBs. [ABSTRACT FROM AUTHOR]

Here, we investigate the oxygen reduction reaction activity of near-monocrystalline platinum nanoflowers presenting a low microstrain to decorrelate the contribution of (i) distorted lattice and (ii) high coordination active sites found within the platinum nanoflower pores to the specific activity enhancement. The results are discussed within the framework of previous investigations onto various catalytic nanostructures. We evidenced that the microstrain of the platinum nanoflowers stands out of the trends previously established for defective platinum-based nanostructures, where the activity is driven by lattice distortion. This indicates that (i) 'defective' structures with low lattice distortion, but high variation in coordination number, can be synthesized and (ii) that their specific activity improvement is comparable to the surface distortion approach in liquid electrolyte. [ABSTRACT FROM AUTHOR]

Abstract The inherent electrochemical performance of supercapacitor electrodes is highly depends on their structures, therefore, numerous efforts are focus on rationally designing and constructing supercapacitor electrodes with hierarchical structures. In this work, we report a facile method for controllable synthesis of hierarchical shell-core structures by anchoring NiO nanospines on concave spherical carbon particles. It is observed that the inner carbon core, acting as a highly efficient current collector, is inherited from the calcination of concave spherical sulfonated polystyrene, while the external shell, resulting from these NiO nanospines, plays the role of active materials. Benefiting from the hierarchical shell-core structures with large specific surface area, additional electroactive sites, reduced interior space, short ions diffusion pathway and intimate electrode/electrolyte contacts, the as-synthesized electrodes exhibit superior electrochemical performance, such as high specific capacitance (1161 F g−1 at a current density of 2 A g−1), good rate capability (839 F g−1 at a high current density of 10 A g−1) as well as long cycling stability (92.4% retention after 3000 cycles at 2 A g−1). We believe that the electrodes are expected to be the most promising candidate for supercapacitors, and more importantly, this strategy plays an important role in the construction of novel hierarchical shell-core structures with superior electrochemical performance for advanced energy storage materials. [ABSTRACT FROM AUTHOR]

Integrating polyaniline (PANI) with different dimensional carbon materials is considered as a promising strategy to solve the disadvantages of PANI electrodes, such as low rate capability and poor cyclic stability. In this work, a novel layer-by-layer sandwiched graphene/PANI nanorods/carbon nanotubes (G/PANI/CNTs) heterostructure has been synthesized. The morphology of the heterostructures has been characterized by XRD, Raman spectroscopy, N 2 adsorption-desorption, XPS, FESEM and TEM. The obtained new layer-by-layer sandwiched heterostructures exhibit intimate interface contacts, fully network-structured CNTs coating, dual physical supports and synergistic effects, which can effective host the electrochemical properties of PANI with the electrolyte and restrain the volumetric changes of PANI. As a result, the electrodes exhibit high specific capacitance (638 F g -1  at 0.5 A g −1 ), good rate capability (88.2% retention from 0.5 A g −1 to 10 A g −1 ) and long cycle stability (93% of the initial specific capacitance after 2000 cycles) when the amount of CNTs is 2 mg. Moreover, a possible mechanism for good performance of the layer-by-layer sandwiched heterostructures has been systematically studied. We believe that this strategy will open up an avenue for the rational design of sandwich structured electrodes for high performance supercapacitors and other electronic devices. [ABSTRACT FROM AUTHOR]

Polyaniline (PANI) is one of the most attractive materials for pseudocapacitors. To enhance the electrolyte diffusion and improve the electrochemical performance of the electrode, the well-designed morphology of PANI is required. Incorporating carbon materials is also benefic on enhancing the cycling stability as well as the mechanical and electrochemical properties of PANI. In this study, a simple solution method is applied to synthesize the particle-deposited tube-like PANI. Due to the well-defined structure, a specific capacitance (C F ) of 437.8 F/g is achieved at the current density of 4 A/g. Furthermore, the self-synthesized graphene oxide (GO) is simply mixed with the particle-deposited tube-like PANI to make a more efficient electrocapacitive material. An enhanced C F value of 475.0 F/g is achieved for the optimized PANI/GO electrode, owing to the synergic effects of the pseudo-capacitance from PANI and the functional groups of GO, as well as the electrochemical double-layered capacitance from GO. After conducting 2000 cycles repeated charge/discharge process, the C F retention of 90% and the average Coulombic efficiency of higher than 90% are also attained for the optimized PANI/GO electrode. [ABSTRACT FROM AUTHOR]

Abstract: Gibbs energy showed that AlCl3 can chloridize Pr6O11 and release Pr(III) ions in the LiCl–KCl–Pr6O11–AlCl3 melts. The co-reduction process of Al(III), Pr(III) and Li(I) ions was investigated in the LiCl–KCl–Pr6O11–AlCl3 melts. Three signals, corresponding to different Al–Pr intermetallic compounds, were observed by cyclic voltammetry, square wave voltammetry and open circuit chronopotentiometry. Potentiostatic and galvanostatic electrolysis were conducted to extract Pr element from LiCl–KCl eutectic melts by forming Al–Pr and Al–Li–Pr alloys, respectively. X-ray diffraction (XRD) indicated that both Al–Pr and Al–Li–Pr alloys comprised Al2Pr phase. The composition of Al–Li–Pr alloys was analyzed by inductive coupled plasma atomic emission spectrometer (ICP-AES). The proportion of Pr element in Al–Li–Pr alloys exceeded 40wt.% when the concentration of AlCl3 reached 8wt.% in the LiCl–KCl–Pr6O11(1wt.%) melts. [Copyright &y& Elsevier]

Abstract: Ultracapacitors of asymmetric configuration have been prepared with activated carbon (AC) and undoped or Mo-doped manganese oxide (MnO2) in 1.0M Na2SO4 electrolyte. Phase analysis shows the AC powder, 1–15μm in size, contains both disordered and graphitic structures, and the undoped and Mo-doped oxide powder, 0.05–0.20μm in particle size, mainly involves amorphous MnO2 and MoO2. CV results indicate the single electrode of AC plus 10wt% Mo-doped MnO2 (A9OM1) is superior to the electrode with undoped MnO2 or high content of doped MnO2, exhibiting features of double layer capacitance at high scan rate and pseudocapacitance characteristics at low scan rate. When assembled with a negative electrode of AC, the capacitor of positive A9OM1 electrode demonstrates the least power loss among three asymmetric capacitors. This asymmetric capacitor also shows a higher capacitance than the symmetric AC capacitor when the current density is less than 8.0Ag−1 in 1.8V potential window. But a higher electrode resistance of A9OM1, in contrast with AC, compromises its capacitance plus. When the energy density of A9OM1 asymmetric capacitor is compared with that of symmetric AC capacitor at the same power level, the capacitance benefit on energy density is restricted to current density≤3.0Ag−1. [Copyright &y& Elsevier]

Abstract: Planar ultracapacitors of miniature interdigital electrode are prepared, using the standard technologies of photolithography and reactive sputtering. The ultracapacitor is denoted by its deposition sequence, for example, hRuO2NRGT indicates pseudocapacitive hydrous RuO2 (hRuO2) and RuO2 nanorods (NR) are grown on an interdigital stack layer of gold (G) and titania (T). The connection between structure and performance is studied through contrasting the hRuO2NRGT capacitor with other capacitors built on a less conducting stack layer or without hydrous RuO2 filling the gaps between the nanorods. The stack layer can be a major source of cell resistance. For instance, a buffer layer of titania could be utilized between the capacitive RuO2 and the Au current collector to overcome the delamination problem. But the less conductive titania also makes its cyclic voltammograms (CV) elliptical and tilted, and causes a pronounced IR drop during the cell discharging. In contrast, CV of the hRuO2NRGT capacitor on a conductive stack layer takes the shape of horizontal rectangle, and its discharge curve shows no sign of IR drop. Filling hydrous RuO2 into the gap reduces the cell resistance between nanorods, improves the discharge performance as well. The power output of hRuO2NRGT, with the two resistances minimized, is 30.6μW at 75μA and 1.23μW at 5μA. [Copyright &y& Elsevier]

Abstract: Electrochemical activities and structural features of Pt/Sn catalysts supported by hydrogen-reduced SnO2 nanowires (SnO2NW) are studied, using cyclic voltammetry, CO stripping voltammetry, scanning electron microscopy, and X-ray diffraction analysis. The SnO2NW supports have been grown on a carbon paper which is commercially available for gas diffusion purposes. Partial reduction of SnO2NW raises the CO tolerance of the Pt/Sn catalyst considerably. The zero-valence tin plays a significant role in lowering the oxidation potential of COads. For a carbon paper electrode loaded with 0.1mgcm−2 Pt and 0.4mgcm−2 SnO2NW, a conversion of 54% SnO2NW into Sn metal (0.17mgcm−2) initiates the COads oxidation reaction at 0.08V (vs. Ag/AgCl), shifts the peak position by 0.21V, and maximizes the CO tolerance. Further reduction damages the support structure, reduces the surface area, and deteriorates the catalytic activity. The presence of Sn metal enhances the activities of both methanol and ethanol oxidation, with a more pronounced effect on the oxidation current of ethanol whose optimal value is analogous to those of PtSn/C catalysts reported in literature. In comparison with a commercial PtRu/C catalyst, the optimal Pt/Sn/SnO2NW/CP exhibits a somewhat inferior activity toward methanol, and a superior activity toward ethanol oxidation. [Copyright &y& Elsevier]