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Prismatic structure is mainly located in the outer layer of mollusk shells. However, there is limited studies on their resistance to wear and the underlying mechanisms. The Vicker's hardness and sliding anti-wear properties of prismatic structures in four species of mollusk shells were systematically investigated for comparisons in the present work. The crystalline types, organic matrix content, structural arrangement, and dimension of prisms are varied among different species. The hardness and wear properties of prismatic structures are, in the first place, determined by the crystalline type, i.e., the aragonite prismatic structures are harder and more wear-resisting than the calcite types. The primary failure mechanism in the prismatic structure during wear tests is three-body abrasion. The volume of the crushed prism particles is directly related to the thickness of organic interface and the hardness of prisms. The organic sheaths form organic films during sliding, and thus lubricate the friction interface to some extent, but higher organic content leads to a wider interface, resulting in a higher plough force at the edge of prisms. A higher plough force gives rise to a severe three-body abrasion. Long and straight prisms perpendicular to the shell surface present a higher wear resistance. Too thin prisms cannot bear the plough force. Therefore, the anti-wear properties of prismatic structures are governed by the joint action of crystalline types, organic matrix, structural arrangement and dimension of basic building blocks. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we report the sphere-like C/CuO and CuO nanocrystals that have been fast prepared by the microwave-assisted hydrothermal method in the presence of green additive d-glucose. The rapid formation mechanism of the C/CuO and CuO nanocrystals and how the d-glucose worked in the microwave-assisted hydrothermal system were discussed in details. The crystal phase, morphology and electrochemical performance were characterized by means of X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM) and electrochemical testing. The XRD patterns indicated that the CuO nanocrystals are pure with monoclinic structure and TEM images showed that the size of the samples could be tunable by adjusting the ratio of d-glucose and metal salt. Finally, a possible growth mechanism for the C/CuO spheres and CuO nanocrystals was proposed and discussed. The electrochemical performance of the products may be influenced by the size and uniformity of the nanocrystals. [Copyright &y& Elsevier]

Abstract: Olivine structure LiMnPO4 has been considered as one of the very promising electrodes for lithium-ion batteries because of their low cost, low toxicity and high voltage plateau compared with LiFePO4. In order to improve the electrochemical performance a key challenge in the field of lithium-ion battery, is to explore and invent suitable synthetic route to control the size and morphology of LiMnPO4. Here a detailed study exploring the novel route of microwave-hydrothermal (MH) synthesis for successfully obtaining LiMnPO4 crystals within few minutes is reported and the reaction process discussed in detail. Variation of the synthetic parameters show that a decrease in reactant concentration could lead to LiMnPO4 nano-platelets orientated in the ac plane with a very high electrochemical performance. The effect of the starting precursor (like, Mn) concentration as a means to tailor LiMnPO4 electrochemical performance is discussed. The effect of alteration of size, morphology, lattice parameters and crystal structure induced by addition of additives like citric acid (H3cit) and sodium dodecyl benzene sulfonate (SDBS) is further described and an example of the first reversible discharge of a product treated with H3cit obtained by MH route as high as 89.0mAh/g, is shown. The general investigation demonstrates that there is a relationship among microwave irradiation condition, crystal structure, morphology and electrochemical performance that can be exploited for the design of next generation lithium batteries. [Copyright &y& Elsevier]

Abstract: To investigate the crystal structure and electrochemical performance of samples synthesized under different microwave solid-state synthesis condition, a series of Li3V2(PO4)3 samples has been synthesized at five different temperatures for 3–5min and at 750°C for various time. The as-synthesized Li3V2(PO4)3 samples are characterized and studied by ICP-AES analysis, X-ray diffraction (XRD), Rietveld analysis, scanning and transmission electron microcopy (SEM and TEM). At relatively lower temperature (650°C) and very short reaction time (3min), pure phase of Li3V2(PO4)3 could be synthesized in microwave irradiation field. The crystal structure and Li atomic fractional coordinate present a significant deviation upon the change of microwave irradiation temperature and time. Relatively, the diffusion ability of lithium cations and the electrochemical performance are affected. Under the proper reaction temperature and time, the carbon-free samples MW750C5m and MW850C3m show the best specific discharge capacity 126.4 and 132mAhg−1 at the voltage range of 3.0–4.3V, near the reversible cycling of two lithium ions per Li3V2(PO4)3 formula unit (133mAhg−1). At the voltage range of 3–4.8V, the sample MW750C5m presents the best initial specific charge capacity of 197mAhg−1, equivalent to the reversible cycling of three lithium ions per Li3V2(PO4)3 formula unit (197mAhg−1). The initial discharge capacity, the samples MW750C5m and MW850C3m present high specific discharge capacity 183.4 and 175.7mAhg−1, respectively. The relationship among microwave irradiation condition, crystal structure, lithium atomic fractional coordinates and the electrochemical performance have been discussed in detail. [Copyright &y& Elsevier]

Abstract: Rod-like orthorhombic LiMnO2 nanocrystals were successfully synthesized using temperature-controlled microwave hydrothermal route (TCMH) in a short time (30min) at a temperature as low as 160°C. o-LiMnO2 obtained by two different methods was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemistry test. SEM revealed that the product obtained in case of TCMH was rod-like with a diameter of 40nm, while the nanoparticles with 200nm diameter were obtained by traditional hydrothermal route (TH). The dramatic formation of o-LiMnO2 in the microwave hydrothermal field influenced the morphology and crystal structure of the final products. The formation and preferred growth orientation mechanism of o-LiMnO2 in the microwave irradiation process was discussed. Electrochemistry performance exhibited that the as-synthesized o-LiMnO2 nanorods reached the maximum discharge capacity of 194.2mAhg−1 at 0.1C rate after several cycles between 2.2 and 4.4V vs. Li+/Li at room temperature, which was higher than the electrochemical performance of o-LiMnO2 obtained by TH. The experimental results showed that the TCMH method provided an effective way for preparing o-LiMnO2 cathode material in lithium-ion batteries. [Copyright &y& Elsevier]

Abstract: Vanadium (V) was used as the central heteroatom in the synthesis of the Keggin-type polyoxometalate {[CH3(CH2)7]4N}3[VMo12O40] (1). This compound was characterized by elemental analysis and single-crystal X-ray diffraction. Compound 1 was used as a bulk-modifier to fabricate the chemically modified ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) carbon paste electrode (1-ILCPE) by direct mixing. The bulk-modified 1-ILCPE showed well-defined cyclic voltammograms with four reversible redox couples in H2SO4 +Na2SO4. The first wave could be ascribed to the reduction of the central V and the last three waves corresponded to the redox processes of the peripheral Mo atoms. The 1-ILCPE presents good electro-catalytic activity not only toward the oxidation of l-cysteine, which is attributed to the function of the central V, but also toward the reduction of hydrogen peroxide, which is attributed to the function of the Mo atoms. Compared with the conventional carbon paste electrode (CPE), the excellent experimental results suggest that the newly developed paste electrode holds great promise in the design of electrochemical devices, such as sensors and biosensors. The promising results are ascribed to the use of an ionic liquid, which forms an excellent charge-transfer bridge and wide electrochemical windows in the bulk of carbon paste electrode. [Copyright &y& Elsevier]

Three dimensional networks, herein carbon coated SnO 2 micron-sized particles are fixed in carbon nanofibers (CNF/SnO 2 @C), is fabricated and synthesized by using hydrothermal method and carbonization. The weight ratio of SnO 2 reaches to 50% of CNF/SnO 2 @C, meanwhile, CNF/SnO 2 @C remains its flexibility. CNF/SnO 2 @C film is directly used as a binder-free anode for lithium ion batteries without conductive additive and polymer binder. The discharge capacities of CNF/SnO 2 @C are 1286 mAh g −1 at 0.05 A g −1 and 397 mAh g −1 at 1 A g −1 , respectively. The buffering effect of CNFs is studied by using ex-situ SEM in the cycled electrodes operated at various lithiation states. The particles size of SnO 2 @C sample increase to 4 μm after 20 charge/discharge cycles, and a serious aggregation of particles occurs in the cycled SnO 2 @C electrode which is in coincidence with its rapidly faded capacity. The particles of CNF/SnO 2 @C sample also present the increased size from the original size of 2 μm to the lithiated size of 4 μm but they are still fixed in CNFs network without any aggregation. The improved specific capacity, cyclic stability and rate performance of CNF/SnO 2 @C are attributed to the structural synergy of CNFs and SnO2 particles, because CNFs as flexible substrate provides excellent conductive channel improving the rate capability and effective network buffering the volume change to promote the cyclic performance. [ABSTRACT FROM AUTHOR]

A series of composites manganese oxide/carbon with one-dimensional structure are synthesized using electrospinning. The phase composition, morphology and electrochemical performance of MnO x /carbon are studied, which affected by the manganese concentration in precursor and subsequent carbonization conditions. The manufacture of MnO x /carbon is composed of two steps including thermal stabilization (at 250 °C in air) and carbonization (at 700 °C in nitrogen). The main functional groups of samples are well identified by FT-IR spectra. The sample Mn33_3h with the lowest manganese content presents the construction structure which amorphous and/or nanosized MnO x with smaller crystal size are grown and enwrapped in carbon fiber during carbonization. Mn33_3h presents the initial charge and discharge capacities of 1054.1 and 665.6 mAh g−1, and the discharge capacity at the 50th cycle remains 99.7% of that at the 2nd cycle. Beside the well rate capability at the range of current densities from 20 to 1000 mA g−1, Mn33_3h presents very good recovery ability after high rate cycling at 1000 mA g−1. The advantages of this composite structure as well as its high capacity make manganese oxide a very attractive candidate as an anode material for the next generation of rechargeable lithium ion batteries. [ABSTRACT FROM AUTHOR]

Abstract: Monoclinic Li3V2(PO4)3 can be rapidly synthesized at 750°C for 5min (MW5m) by using temperature-controlled microwave solid-state synthesis method (TCMS). The carbon-free sample MW5m presents well electrochemical properties. In the cut-off voltage 3.0–4.3, MW5m presents a charge capacity 132mAhg−1, almost equivalent to the reversible cycling of two lithium ions per Li3V2(PO4)3 formula unit (133mAhg−1), and discharge capacity 126.4mAhg−1. In the cut-off voltage 3.0–4.8V, MW5m shows an initial discharge capacity of 183.4mAhg−1, near to the theoretical discharge capacity. In the cycle performance, the capacity fade of Li3V2(PO4)3 is dependent on the cut-off voltage and the preparation method. [Copyright &y& Elsevier]

A novel heterostructure of NiO/Ni 3 S 2 nanoflake is synthesized and composited with carbon nanofibers (CNF) membrane. NiO/Ni 3 S 2 nanoflakes are homogeneously dispersed in CNF network, herein, NiO/Ni 3 S 2 like leaf and CNF like branch. Carbon nanofibers network efficiently prevents the pulverization and buffers the volume changes of NiO/Ni 3 S 2 , meanwhile, NiO/Ni 3 S 2 nanoflakes through the conductive channels of carbon nanofibers own improved Li + diffusion ability and structural stability. The capacity of NiO/Ni 3 S 2 /CNF reaches to 519.2 mA g −1 after 200 cycles at the current density of 0.5 A g −1 while NiO/Ni 3 S 2 fades to 71 mAh g −1 after 40 cycles. Owing to the synergetic structure, the resultant binder-free electrode NiO/Ni 3 S 2 /carbon nanofibers shows an excellent reversible lithium storage capability. [ABSTRACT FROM AUTHOR]

• Micron single crystals of LiNi 0.8 Co 0.1 Mn 0.1 O 2 were prepared by molten salt method. • SC-NCM has lower cationic mixing accompanying with ordered growth of micron crystal. • Ni(III) in SC-NCM is majority benefiting for cyclic stability. • After 300 cycles at 5C rate SC-NCM remains 80.7 mAh g−1 and retention 62.0%. • Micron single crystals on electrochemical property benefit for structure stability. In this work, Ni-rich layered micron-sized LiNi 0.8 Co 0.1 Mn 0.1 O 2 (SC-NCM) single crystals were prepared by wet ball-milling and molten-salt methods. Through X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectrometry (XPS), the differences between SC-NCM and a commercial polycrystalline micron-sized NCM material (M-NCM) were compared. An extended sintering process for SC-NCM plays a role in decreasing cationic mixing accompanied by the ordered growth of single crystals. The SC-NCM sample presents homogeneous micron-sized crystals. The Ni3+ content in SC-NCM constitutes 90.45% of the total Ni content, while the Ni3+ in M-NCM constitutes only 68.49%. The existence of Ni2+ in ternary cathode materials is harmful to electrochemical stability and cyclic stability. The initial specific discharge capacity of SC-NCM (168 mAh g−1) is lower than that of M-NCM (187 mAh g−1); however, M-NCM shows a rapid decline in capacities and voltage plateaus from the 1st to 180th cycle. After 300 cycles at a 5 C rate, M-NCM remains only 42 mAh g−1 with a capacity retention rate of only 25.6% in comparison with SC-NCM with a remaining capacity of 80.7 mAh g−1 and a capacity retention of 62.0%. The effect of micron-sized single crystals on electrochemical properties during redox reactions is negative in terms of conductivity but positive in terms of structural stability. [ABSTRACT FROM AUTHOR]

Abstract: In this work, high specific capacitance of Mn3O4 is successfully synthesized via ultrasonic and hydrolyzation at room temperature. The crystal structure, phase and the electrochemical performance are dependent on the preparation conditions, such as ultrasonic time, reaction temperature, and the organic solvent used, etc. The effect of ultrasonic time and the presence of various solvents are well discussed in the crystal growth mechanism and improved supercapacitor performance of Mn3O4. The almost 100% yielded Mn3O4 nanoparticles via ultrasonication for 6h at room temperature exhibit high specific capacitances (261Fg−1 at 0.4Ag−1 and 140Fg−1 at 40Ag−1) as well as excellent cycle life. The high yield and convenient synthetic route at room temperature make readily scaled-up production of transition metal oxides for electrochemical applications. [Copyright &y& Elsevier]

Abstract: To substitute minor Mn2+ by the transition metal ion M=Mg2+, V3+, Fe2+, Co2+, or Gd3+, LiMn0.95M0.05PO4 samples are synthesized by a solid-state reaction route. The interpretation of doping effects is complicated by the interrelations between doping microstructure and morphology, because the crystal structure would be affected by the doped elements. The lattice structure and deviation of Li–O bond lengths of the doped LiMnPO4 are refined by XRD refinement. All the samples present a couple of oxidation and reduction peaks in cyclic voltammetry, corresponding to a redox Mn3+/Mn2+ reaction coupled with the extraction/reinsertion process of Li+ in LiMnPO4 structure. During charge/discharge process, the electron flowing and Li+ cation diffusion in the various doped LiMnPO4 samples should be different thermodynamic and kinetic process. For further studying which step in thermodynamic and kinetic process would affect or control the electrochemical performance, the initial charge/discharge capacities and cycleability of doped LiMnPO4 samples are obtained under different voltage range (from 2.7 to the upper cut-off voltage 4.4, 4.6 and 4.8V, respectively) and different environment temperatures (0, 25, and 50°C). At relative higher measuring temperature, the discharge capacity of Co-doped LiMnPO4 shows 151.9mAhg−1. [Copyright &y& Elsevier]

Abstract: High quality Mn-doped CdS nanowires have been synthesized through solvothermal route with Polyethylene Glycol-400 as inducing template at 170°C. The nanowires had a uniform single-crystal hexagonal structure and preferentially grew along [001] direction. Undoped and doped CdS nanowires with 1% Mn have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and energy dispersive X-ray analysis (EDX). Also, investigations into the optical properties of the Mn2+ doped CdS nanowires were conducted with UV–vis absorption spectroscopy and photoluminescence emission spectroscopy. The luminescence due to Mn2+ intra-3d transition is clearly observed near 595nm in Mn-doped CdS nanowires. [Copyright &y& Elsevier]

Lithium-rich cathode materials have the potential for applications in high energy lithium-ion batteries, but they suffer from a low rate performance and an inferior cycling stability. In this work, Li 1.167- x K x Mn 0.583 Ni 0·25 O 2 (x = 0, 0.025, 0.05 and 0.075) samples are synthesized and characterized. In addition, K+ doping results in small perturbations in the crystal structure of Li 1.167- x K x Mn 0.583 Ni 0·25 O 2 , such as the Li–O bond lengths, lattice parameters and the oxidation states of manganese, which effectively improves the lithium diffusion ability and hinders the detrimental interphase growth of the spinel phase during cycling. In a half-cell, Li 1·117 K 0·05 Mn 0·583 Ni 0·25 O 2 (LK2MNO) with an optimized doping quantity of K+ delivers the best capacities of 152.0 mAh g−1 after 100 cycles at a 1C rate and 82.9 mAh g−1 after 300 cycles at a 10C rate, in comparison with Li 1·167 Mn 0·583 Ni 0·25 O 2 , which has a capacity of only 126.0 and 33.3 mAh g−1. In the full-cell with graphite as the negative electrode, LK2MNO delivers an initial capacity of 249.9 mAh g−1 at a 0.1C rate and retains 90.8% of its initial capacity after 100 cycles. The surface chemical states of the positive electrode and negative electrodes after 100 cycles is studied by ex situ SEM and XPS measurements, and the results reveal that an appropriate K+ doping amount effectively hinders the dissolution of Mn2+ from the cathode material and decreases the decomposition of electrolytes to some degree. K+ doping in Mn-based lithium-rich cathode materials improves the lithium diffusion ability and hinders the detrimental interphase growth of the spinel phase during cycling. In full cell, the LK2MNO sample delivers an initial capacity of 249.9 mAh g−1 at a 0.1C rate and retains 90.8% of its initial capacity after 100 cycles. The surface chemical state of the positive and negative electrodes after 100 cycles reveal that K+ doping effectively suppresses side reactions and electrolyte decomposition. Image 1 • K+ doping results in small perturbations in Li 1.167- x K x Mn 0.583 Ni 0·25 O 2 structure. • Potassium doping decreases the detrimental interphase growth of spinel phase during cycling. • Expanding interlayer spacing by K+ provide fast conductive channel for Li+ diffusion. • LK2MNO delivers 249.9 mAh g−1 and remains 90.8% of initial capacity after 100 cycles. • K+ doping suppresses side reactions and electrolyte decomposition during cycling. [ABSTRACT FROM AUTHOR]