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Abstract SiO x has emerged as an important alternative to silicon as the high capacity anode host to store lithium due to its smaller volume change upon lithiation. However, conventional synthesis methods generally require harsh reaction conditions, making its production in industrial scale much challenging. Herein, a safe, economical and scalable approach is developed for SiO x using highly abundant natural silica as starting material via a magnesio-mechanochemical reduction process induced by ball-milling. The as-prepared SiO x is intrinsically porous and comprised of mixed nano clusters of SiO 2 and Si. Upon lithiation, SiO 2 nano domains convert into lithium silicates and Li 2 O, which help to absorb Si volume expansion and participate in the formation of a stable solid electrolyte interface. Such synergistic effect leads to exceptional cycling stability up to 2000 cycles with 71.3% capacity retention under 4 A g−1. After blending with graphite, a high areal capacity of 2.64 mAh cm−2 demonstrates stable cycling of 89.7% retention over 200 cycles with an high initial Coulombic efficiency of 82.3%, implying the feasibility for practical applications. Structural and compositional characterizations reveal the involved chemistry and evolution mechanism of the formed solid electrolyte interface upon cycling, providing guidelines of designing future silicon-based materials for future Li-ion batteries. Graphical abstract Image 1 Highlights • Synthesis of nano SiO x from natural silica by facile ball milling. • Exceptional long-term cycling stability up to 2000 cycles was demonstrated. • Superb structural stability derived from intrinsic porosity and the grown stable SEI. • Blending with graphite exhibited application feasibility with high areal capacity. [ABSTRACT FROM AUTHOR]

A previous study is focused on high temperature cycling of industrially manufactured Li-ion pouch cells (NMC-111/Graphite) with different electrolytes at 80 °C [JPS 373 (2018) 172–183]. Within this article the same test set-up is used, with cells stored for 30 days at different open circuit potentials and various electrolytes instead of electrochemical cycling. The most pronounced cell degradation (capacity fade and resistance increase) happens at high potentials. However appropriate electrolyte formulations are able to suppress ageing conditions by forming passivating surface films on both electrodes. Compared with electrochemical cycling at 80 °C, cells with enhanced electrolytes only show a slight resistance increase during storage and the capacity fade is much lower. Additionally it is shown for the first time, that the resistance is decreasing and capacity is regained once these cells are cycled again at room temperature. This is not the case for electrolytes without additives or just vinylene carbonate (VC) as an additive. It is further shown that the resistance increase of cells with the other electrolytes is accompanied by a reduction of the cell volume during further cycling. This behaviour is likely related to the reduction of CO 2 at the anode to form additional SEI layer components. [ABSTRACT FROM AUTHOR]

Composite electrode materials Li[Li 0.13 Ni 0.2 Mn 0.47 Co 0.2 ]O 2 (LNMC)–CeO 2 –С are obtained by the coprecipitation of Co, Ni, Mn and Ce hydroxides followed by the coating of LNMC–CeO 2 composites with pyrolytic carbon. The introduction of 5% CeO 2 promotes the reduction of LNMC grain size from 190–230 to 100–170 nm and the corresponding increase in the electrochemical capacity of LNMC-CeO 2 composite. The pyrolytic coating consists of the network of 2–5 nm polymer-carbon particles at the surface of LNMC crystallites. The electrochemical impedance spectroscopy data, which was performed after the galvanostatic cycling, demonstrated considerably lower charge transfer resistance of the carbon-coated composites compared to the bare LNMC and the LNMC-CeO 2 composites. The values of the discharge capacity of LNMC-CeO 2 -C composites are superior to the capacity of LMNC-CeO 2 and LMNC-C composites at all discharge rates (C/10 – 5C). The increase of the upper boundary of potentials to 4.8 V after cycling at 5C (U – 2÷4.6 V) promotes the increase of low rate electrochemical capacity of LNMC-CeO 2 -C composite to 220 mAh g −1 . [ABSTRACT FROM AUTHOR]

The aim of the paper is to present a promising approach for recycling high value-added metals from the cathode materials of spent LIBs. The synthesis process of NCM cathode material enlightened us to apply reduction roasting to break LiNi x Co y Mn z O 2 into simple compounds or metals. Accordingly, the effect of several factors such as temperature, carbon dosage and roasting time is assessed on the leaching efficiency of valuable metals. The roasted products are analyzed by XRD and SEM-EDS, and the results show that the cathode material after reduction roasting is primarily transformed into Li 2 CO 3 , Ni, Co and MnO. However, the solubility of Li 2 CO 3 is relatively low, so carbonated water leaching is used to treat the roasted products. Then the filtrate is evaporated for the preparation of pure Li 2 CO 3 , and residue is leached to recycle other metals with H 2 SO 4 . The results indicate that, after roasted at 650 °C for 3 h with 19.9% carbon dosage, 84.7% Li is preferentially recovered via carbonated water leaching, and more than 99% Ni, Co and Mn are recycled via acid leaching without adding reductant. Finally, the products of Li 2 CO 3 , NiSO 4 , CoSO 4 and MnSO 4 are obtained. The process have great potential for industrial-scale recycling from spent LIBs. [ABSTRACT FROM AUTHOR]

TiO 2 -reduced graphene oxide (rGO) nanocomposite (TiO 2 -rGO) is fabricated by microwave-assisted forced hydrolysis and examined as prospective electrode for energy storage applications, especially in Li-ion battery (LIB) and Li-ion capacitor (LIC). First, the uniformly distributed nanoscopic TiO 2 particulates (∼3 nm) over rGO nanosheets is evaluated as anode in half-cell assembly to ascertain the Li-insertion behavior and found that ∼0.68 mol Li (∼227 mAh g −1 ) is reversible. Then, “rocking-chair” type LIB is fabricated with spinel LiMn 2 O 4 cathode, and the LiMn 2 O 4 /TiO 2 -rGO assembly exhibits high capacity (∼120 mAh g −1 at 0.1 C rate), good rate capability (∼53 mAh g −1 at 1 C rate), and excellent cycleability (∼90% initial reversible capacity after 1000 cycle) as well. Similarly, the LIC is also constructed with activated carbon cathode, and such configuration delivered a maximum energy density of ∼50 Wh kg −1 with ∼82% retention after 4000 cycles. The synergistic effect of both rGO and anatase nanoparticles provides excellent energy efficiency and battery performance in different kind of Li-ion based energy storage devices. [ABSTRACT FROM AUTHOR]

In this study, a metastable form of vanadium dioxide, denoted as VO 2 (B), has been successfully synthesized under solvothermal condition. However, the as-received VO 2 (B) suffers from fast capacity fading and poor high-rate performance. In order to overcome these problems, the as-received VO 2 (B) is solvothermally treated with reduced graphene oxide (rGO) to produce VO 2 (B)/rGO composite. As a result, the resulting electric conductivity of the VO 2 (B)/rGO composite is improved to ∼10 −4 cm S −1 (from ∼10 −7 S cm −1 for the as-received VO 2 (B)). Electrochemical data of the VO 2 (B)/rGO composite, tested in both Li and Na cells, shows markedly enhanced electrochemical performance compared to bare VO 2 (B). The effect of electro-conducting rGO is more evident at high rates. [ABSTRACT FROM AUTHOR]

MnO 2 /reduced graphene oxide (rGO) nanocomposites were synthesized via a simple solution method at room temperature for use in Li-ion batteries. Owing to the mesoporous features as well as the high electrical conductivity of rGO, the overall electronic and ionic conductivities of the nanocomposite were increased, resulting in improved electrochemical properties in terms of specific capacity, rate capability, and cyclability. In particular, as-prepared nanocomposites showed 222 and 115 mAh g −1 at a current density of as high as 5 and 10 A g −1 , and the specific capacitance was well maintained after 400 cycles. In addition, MnO 2 , via composite formation with rGO, permitted the additional conversion reaction between MnO and Mn 3 O 4 , resulting in the reduction of the initial irreversible capacity despite the high first discharge capacity caused by the large specific surface area. [ABSTRACT FROM AUTHOR]

A novel binder-free reduced graphene oxide/silicon (RGO/Si) composite anode has been fabricated by a facile doctor-blade coating method. The relatively low C/O ratio plays an important role for the fabrication of the bind-free multilayered RGO/Si electrode with silicon nanoparticles encapsulating among the RGO sheet layers. The RGO provides the electron transport pathway and prevents the electrode fracture caused by the volume changes of active silicon particles during cycling. The RGO/Si composite anode with a silicon content of 66.7% delivers a reversible capacity of 1931 mAh g −1 at 0.2 A g −1 and still remains 92% of the initial capacity after 50 cycles. [ABSTRACT FROM AUTHOR]

Carbon coated spherical Na 2 FePO 4 F particles with typical diameters from 500 nm to 1 μm have been synthesized through an economical carbothermal reduction method with a simple apparatus. Mixed carbon source consists of citric acid and phenolic resin can form highly graphitized carbon and remarkably improve the electrical conductivity. When cycled against lithium, Na 2 FePO 4 F/C cathodes deliver maximum discharge capacity of 119 mAh g −1 at a low rate of 0.05 C. Reversible capacity of 110 mAh g −1 , 74 mAh g −1 and 52 mAh g −1 can be obtained at 0.1 C, 1 C and 2 C rates, respectively. And after 30 cycles at 0.1 C, 91% of the discharge capacity can still be maintained. The electrochemical kinetic characteristic of electrode material is investigated by EIS and the apparent Li + diffusion coefficient in the Li/Na 2 FePO 4 F system is evaluated to be as high as 1.152 × 10 −11 cm 2 s −1 . This study demonstrates that the practical and economical synthesis process can be a promising way for industrial production of high performance Na 2 FePO 4 F/C electrode material for large-scale lithium ion batteries. [ABSTRACT FROM AUTHOR]

Owing to their multiple redox couples, titanium–niobium-based oxides are still considered promising candidates for use as anodes for safe, rechargeable lithium ion batteries with high energy and power densities. Titanium–niobium-based oxide electrodes have, however, exhibited relatively poor cycling performance as a result of pulverization. In this study, we report on a simple two-step solid-state reaction route for producing hybrid composites of Ti 2 Nb 10 O 29 (TNO) anchored on reduced graphene oxide (RGO), and the electrochemical performance of the resulting TNO/RGO composites. Solid-state reactions enable both the formation of TNO and the uniform distribution of RGO in the TNO/RGO composites. The TNO/RGO composites exhibited discharge and charge capacities of 261 and 256 mAh g −1 , respectively, with much better cycling performance (182 mAh g −1 after the 50th cycles) and rate capability (165 mAh g −1 at a current density of 500 mA g −1 ) compared to the pure TNO. [ABSTRACT FROM AUTHOR]

This work explores low cost methods for the preparation of Si/nano-graphite sheets (NanoGs) composite materials for Li ion battery. The Si/NanoGs composites are prepared by magnesium thermal reduction of mechanical mixture of fumed SiO 2 and NanoGs under Ar atmosphere. The structure of the samples is characterized by XRD, Raman spectroscope, SEM, and HRTEM. The results show that highly crystallized Si nanoparticles with a sheet-like morphology are uniformly distributed on the surface of NanoGs (both edge and a-b plane). The average diameter of Si nanoparticles is ∼20 nm. Electrochemical characterization shows that an electrode has an initial lithium storage capacity of 1702.9 mAh g −1 at a current of 100 mA g −1 . The storage capacity decreases to 975.7 mAh g −1 after 100 cycles. Since cheap commercial fumed SiO 2 and graphite are used and the process is simple and easy to scale up, with further improvement, the method has potential for use in large scale production of high energy density Si/NanoGs anode materials at low cost. [ABSTRACT FROM AUTHOR]

Small amount of reduce graphene oxide (rGO) nanosheets modified Li 4 Ti 5 O 12 nanoparticles composite has been synthesized by a facile and environmental in-situ hydrothermal reaction with subsequent annealing. The small amount of rGO (only 1.2 wt. %) greatly improves the whole morphology and electrochemical performance of composite. The nanoparticles uniformly grow on the rGO nanosheets effective suppressing the agglomeration and enhancing the specific surface area. Meanwhile, the special discharge capacity is 187 mAh g −1 at 1 C and the high rates discharge capacity is 128 mAh g −1 at 80 C (discharge-charge time only 33s). In particular, the cells remain in good work condition after 2000 cycles at 80 C, which credibly evidence the excellent electrochemical performance as an anode for high-power LIBs. [ABSTRACT FROM AUTHOR]

A detailed processing cost breakdown is given for lithium-ion battery (LIB) electrodes, which focuses on: 1) elimination of toxic, costly N -methylpyrrolidone (NMP) dispersion chemistry; 2) doubling the thicknesses of the anode and cathode to raise energy density; and 3) reduction of the anode electrolyte wetting and SEI-layer formation time. These processing cost reduction technologies generically adaptable to any anode or cathode cell chemistry and are being implemented at ORNL. This paper shows step by step how these cost savings can be realized in existing or new LIB manufacturing plants using a baseline case of thin (power) electrodes produced with NMP processing and a standard 10–14-day wetting and formation process. In particular, it is shown that aqueous electrode processing can cut the electrode processing cost and energy consumption by an order of magnitude. Doubling the thickness of the electrodes allows for using half of the inactive current collectors and separators, contributing even further to the processing cost savings. Finally wetting and SEI-layer formation cost savings are discussed in the context of a protocol with significantly reduced time. These three benefits collectively offer the possibility of reducing LIB pack cost from $502.8 kW h −1 -usable to $370.3 kW h −1 -usable, a savings of $132.5/kWh (or 26.4%). [ABSTRACT FROM AUTHOR]

In using a LiPF 6 /ethylene carbonate–dimethyl carbonate electrolyte for lithium ion batteries (LIBs), a certain reductive reaction is known to occur at a relatively high potential (ca. 2.6 V vs. Li + /Li) on Sn electrode, but its details are still unknown. By means of in-situ X-ray reflectometry, X-ray photoelectron spectroscopy, scanning electron microscopy observations and electrochemical measurements (by using mainly Sn electrode, and additionally Pt, graphite electrodes), we have found out that this reduction eventually forms an inactive passivation-layer consisting mainly of insulative LiF ascribed to the reductive decomposition of LiPF 6 , which significantly affects the battery cyclability. In contrast, a solid-electrolyte interphase (SEI) is formed by the reductive reaction of the solvent at ca. 1.5 V vs. Li + /Li, which is lower than the reduction potential of LiPF 6 . However, we have found that the formation of SEI preempts that of the passivation layer when holding the electrode at a potential lower than 1.5 V vs. Li + /Li. Consequently, the cyclability is improved by suppressing the formation of the inactive passivation layer. Such a pretreatment would be quite effective on improvement of the battery cyclability, especially for a relatively noble electrode whose oxidation potential is between 1.5 V and 2.6 V vs. Li + /Li. [ABSTRACT FROM AUTHOR]

Flower-like hydrogenated TiO 2 (B) nanostructures have been synthesized via a facile solvothermal approach combined with hydrogenation treatment. The obtained TiO 2 (B) nanostructures show uniform and hierarchical flower-like morphology with a diameter of 124 ± 5 nm, which are further constructed by primary nanosheets with a thickness of 10 ± 1.2 nm. The Ti 3+ species and/or oxygen vacancies are well introduced into the structures of TiO 2 (B) after hydrogen reduction, resulting in an enhancement in the electronic conductivity (up to 2.79 × 10 −3 S cm −1 ) and the modified surface electrochemical activity. When evaluated for lithium storage capacity, the hydrogenated TiO 2 (B) nanostructures exhibit enhanced electrochemical energy storage performances compared to the pristine TiO 2 (B) nanostructures, including high capacity (292.3 mA h g −1 at 0.5C), excellent rate capability (179.6 mA h g −1 at 10C), and good cyclic stability (98.4% capacity retention after 200 cycles at 10C). The reasons for these improvements are explored in terms of the increased electronic conductivity and the facilitation of lithium ion transport arising from the introduction of oxygen vacancies and the unique flower-like morphologies. [ABSTRACT FROM AUTHOR]

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]

Abstract: In this manuscript, we present a facile and friendly wet chemical method to prepare monodisperse SnO2 nanocrystals assembled on reduced graphene oxide (RGO). Aided with sodium dodecyl sulfonate, small SnO2 nanoparticles (∼5 nm) are deposited onto the flexible support evenly and tightly. A cheap compound, urea, is used for the controlled precipitation of SnO2 and the reduction of graphene oxide. When tested as the anode material, the hybrid composite electrode delivers excellent cyclability at high current density, such as high reversible capacity over 1000mAhg−1 after 400 cycles at 0.5Ag−1 and ∼560mAhg−1 after 400 cycles at 1Ag−1. The composites also exhibit superior rate capability varying from 0.1 to 4Ag−1, and possess capacity of 423mAhg−1 at 4Ag−1. This synthesis strategy seems to be suitable for industrial production and can also be extended to produce a variety of metal oxide/RGO composites. [Copyright &y& Elsevier]

Abstract: A microwave-assisted hydrothermal approach combined with carbothermal reduction has been developed to synthesize monodisperse porous LiFePO4/C microspheres, which possess the diameter range of 1.0–1.5 μm, high tap density of ∼1.3 g cm−3, and mesoporous characteristic with Brunauer–Emmett–Teller (BET) surface area of 30.6 m2 g−1. The obtained microspheres show meatball-like morphology aggregated by the carbon-coated LiFePO4 nanoparticles. The electrochemical impedance spectra (EIS) results indicate that carbon coating can effectively enhance both of the electronic and ionic conductivities for LiFePO4/C microspheres. The Li-ion diffusion coefficient of the LiFePO4/C microspheres calculated from the cyclic voltammetry (CV) curves is ∼6.25 × 10−9 cm2 s−1. The electrochemical performance can achieve about 100 and 90 mAh g−1 at 5C and 10C charge/discharge rates, respectively. As cathode material, the as-prepared LiFePO4/C microspheres show excellent rate capability and cycle stability, promising for high power lithium-ion batteries. [Copyright &y& Elsevier]

Abstract: Lithium-ion cells, especially when used in electric vehicles at varying operation conditions, require a sophisticated battery management to ensure an optimal operation regarding operation limits, performance, and maximum lifetime. In some cases, the best trade-off between these conflictive goals can only be reached by considering internal, non-measurable cell characteristics. This article presents a data-driven model-reduction method for a strict electrochemical model. The model describes the charging process of a lithium-ion cell and possibly occurring degradation effects in a large temperature range and is presented in Part I of this contribution. The model-reduction process is explained in detail, and the gained model is compared to the original electrochemical model showing a very high approximation quality. This reduced model offers a very low computation complexity and is therefore suitable for the implementation in a battery management system (BMS). Based on this model, an advanced charging strategy is presented and evaluated for possible reductions in charging times especially at low temperatures. [Copyright &y& Elsevier]

Abstract: In this study, size effect of NiO particles has been studied as the anode material of lithium ion battery. It is found that NiO nanoparticles synthesized in confined space of ordered mesoporous silica behave anomalous high capacity and higher energy efficiency than sub-micro-sized NiO does. The higher energy efficiency is resulted from the reduction of the hysteresis loop between charge and discharge voltage plateaus, the main drawback of conversion reaction-based metal oxide anode materials. The interesting behavior is proposed to be the reversible formation/dissolution of solid electrolyte interphase (SEI) layers associated with 3-D porous, originally nanostructured NiO electrode that is able to remain stable during charge–discharge process. [Copyright &y& Elsevier]

Abstract: A new method for a facile synthesis of nano-silicon/carbon mesoporous composite is proposed. Silicon nanoparticles can be obtained through the magnesium silicide reduction of amorphous silica using high energy mechanical milling process. And mesoporous carbon matrix is fabricated via simple carbon coating method on Si nanoparticles followed by chemical etching of preexisting magnesium oxide nano-particles. This nano-silicon/carbon mesoporous composite electrode shows an excellent electrochemical performance as an anode for lithium ion batteries, achieving a reversible capacity of c.a. 1600 mAh g−1 over 50 cycles at a current of 1.0 A g−1 and superior rate capabilities with reversible capacity of about 1530 mAh g−1 at a discharge current density of 3 A g−1. [Copyright &y& Elsevier]

Abstract: Carbon-coated Li3VO4 sample is synthesized by a simple sol–gel method. X-ray diffraction and X-ray photoelectron spectroscopy results show that single-phase Li3VO4 can be obtained in a reducing atmosphere with the valence of vanadium of +5. The final product sintered at 650 °C demonstrates a favorable electronic conductivity with 6.12% residual carbon. Electrochemical testing shows that the carbon-coated Li3VO4 sample display a discharge capacity of 662.6 mAh g−1 and 507.4 mAh g−1 at 0.18C in the first and the second cycle, respectively, and a reversible capacity (charge capacity) of ∼480.0 mAh g−1 can be obtained in the second cycle. Furthermore, the discharge–charge capacity of the sample can retain ∼180 mAh g−1 and ∼90 mAh g−1 at 12C and 40C, respectively. [Copyright &y& Elsevier]

Abstract: In this paper, we report a simple sol–gel method for the synthesis of a composite containing reduced graphene oxide (R-GO) embedded within nano LiFePO4 particles for a lithium-ion battery cathode. This composite has an effective electron pathway and a highly meso-porous structure as compared to conventional LiFePO4. Highly conductive R-GO, together with the meso-porosity results in a material that has good electronic conductivity and high electrolyte permeability. Electrodes fabricated from the composite exhibited excellent performance when evaluated as lithium-ion battery cathodes, including compared to pristine LiFePO4. The electrode of the R-GO composite exhibits excellent rate capabilities of 125 mAh g−1 at 10 C, whereas pristine LiFePO4 could deliver only 81.5 mAh g−1 at the same condition. It also achieves an improved cyclability with capacity retention ratios of 92.48% after 200 cycles at 10 C, as well. [Copyright &y& Elsevier]

Abstract: We developed hydrogen iodide (HI) reduction of rGO and surfactant-assisted chemical reaction- deposition method to form hybrid material of sulfur (S) encapsulated in reduced graphene oxide (rGO) sheets for rechargeable lithium batteries. The surfactant-assisted chemical reaction–deposition method strategy provides intimate contact between the S and graphene oxide. Chemical reduced rGO with high conductivity as carbon coating layer prevented the dissolution of polysulfide ions and improved the electron transfer. This novel core–shell structured S@rGO composites with high S content showed high reversible capacity, good discharge capacity retention and enhanced rate capability used as cathodes in rechargeable Li/S cells. We demonstrated here that an electrode prepared from a S@rGO with up to 85 wt% S maintains a stable discharge capacity of about 980 mAh g−1 at 0.05 C and 570 mAh g−1 at 1C after 200 cycles charge/discharge. These results emphasize the importance of rGO with high electrical conductivity after HI-reduced rGO homogeneously coating on the surface of S, therefore, effectively alleviating the shuttle phenomenon of polysulfides in organic electrolyte. Our surfactant-assisted chemical reaction-HI reduction approach should offer a new technique for the design and synthesis of battery electrodes based on highly conducting carbon materials. [Copyright &y& Elsevier]

Abstract: Thin films of manganese oxides have been deposited on Cu foils by radio-frequency (RF) sputtering under different conditions. Crystalline MnO films cannot be obtained but Mn3+/M4+ oxides are formed when the growth proceeds under the Ar atmosphere, due to the oxidation of MnO. While they can be obtained under the Ar:H2 (95:5 vol%) reduction atmosphere at both room temperature and 500 °C. The latter films in thickness of ∼0.5 μm exhibit an initial coulombic efficiency of 75%, reversible capacities of 380 μAh cm−2 μm−1 (∼700 mAh g−1) at 4 μA cm−2 (∼0.05 C) after 100 cycles, and 230 μAh cm−2 μm−1 (∼428 mAh g−1) at 20 C. These values demonstrate that the sputtering-grown MnO films here exhibit excellent cyclability and rate performance in comparison to the reported data of MnO anodes. Pure phase with low oxidation state and certain porosity could be favorable factors accounting for such improved electrochemical performance. [Copyright &y& Elsevier]

Abstract: The composite of manganese monoxide and multi-walled carbon nanotubes (MnO/MWNTs) is prepared hydrothermally by MWNTs and KMnO4 followed with a sintering process. After reducing KMnO4 as the reductant, the leftover MWNTs are found randomly distributed in the final MnO rods forming a conducting network. More importantly, they can buffer the volume change of MnO during lithium incorporation/extraction. As a result, the rate capability and cycling performance of MnO as an anode material for lithium ion batteries are significantly improved. The MnO/MWNTs composite shows a reversible capacity as high as 770.6 mA h g−1 and 455.3 mA h g−1 at the current density of 7.21 mA g−1 and 310.23 mA g−1 respectively between 0.01 and 3.5 V (vs. Li/Li+ hereafter). Furthermore, the capacity retention is over 92.4% after 200 cycles at 216.14 mA g−1 between 0.01 and 3.0 V. [Copyright &y& Elsevier]

Abstract: Effects of Li amount used for anode on the discharge capacitance of a lithium-air battery were studied in order to investigate the effects of Li usage. On the basis of Ketjenblack air electrode, electrochemical analysis were performed in the voltage range of 4.5–2.0 V. Because the amount of Li limits the overall discharge capacity, the capacity decreases with decreasing the Li amount in the cell. Although only 370 mAh g−1 (gram of air electrode) of capacity was obtained by reducing the Li amount to 0.9 mg, almost 100% of Li can be used for discharge and it is corresponded to 4111 mAh g−1 (gram of Li) with reasonable cycle stability. To confirm the residual amount of Li on anode, ICP measurement was performed after first discharge. Decrease in capacity with cycle number can be assigned to the decreased amount of Li dissolved and this could be related with formation of dendrite and porous Li deposition. [Copyright &y& Elsevier]

Abstract: Reduced graphene oxides have been prepared via controllably thermal and chemical reduction processes. The structure, surface chemistry and electrochemical behaviors of reduced graphene oxides are investigated by Raman spectroscopy, N2 adsorption, temperature-programmed desorption, Fourier-transform Infrared spectroscopy, X-ray photoelectron spectroscopy, as well as charge/discharge measurements. The enhanced reversible capacity of reduced graphene oxides is attributed to specific functionalities rather than to exceptional large specific surface area or structure defect. The contributed capacities at potential higher than 1.5 V and in region of 0.8–1.5 V are attributed dominantly to phenol groups and cyclic edge ether groups, respectively. These findings may be beneficial to the material design of graphene-based anode materials with high energy density. [Copyright &y& Elsevier]

Abstract: A series of Pt x Co y (x:y =4, 2, 1, and 0.5) alloy nanoparticles deposited on Vulcan XC-72 carbon was prepared through a chemical reduction method. The structures and morphologies of the as-prepared nanoparticles were characterized by X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy, which revealed the formation of Pt–Co alloys during the co-reduction process. Pt x Co y alloy nanoparticles were applied as catalysts in lithium-air batteries. Through electrochemical testing, we found that the Pt based alloy nanocatalysts significantly increased the specific capacity of lithium-air batteries and the increase of Co content in Pt x Co y alloy nanoparticles further enhanced the catalytic activity. This result illustrated that Pt x Co y alloy nanoparticles could be used as an efficient catalyst material for lithium-air batteries with the feature of much reduced cost, but drastically increased catalytic activity. [Copyright &y& Elsevier]

Abstract: An efficient synthesis is used for the first time to prepare CuO/reduced graphene oxide nanocomposite anode materials for lithium ion batteries. Initially, copper oxide (CuO) nanoparticles are synthesized via a simple, facile and inexpensive microwave-assisted method within short reaction times (<20 min) and subsequent heat treatment at 500 °C for 5 h. The obtained pure CuO nanoparticles are mixed with 10 wt% of graphene nanosheets by the use of spex mill for 1 min. By short-time spex-milling, a unique CuO/reduced graphene oxide nanocomposite is obtained with a microstructure of multi-scale CuO nanoparticles homogeneously dispersed in a graphene matrix. The synthesized samples are characterized using X-ray diffraction and field-emission transmission electron microscopy studies. The spex-milled nanocomposite anode exhibits better electrochemical performance with higher reversible capacity and excellent cyclability in comparison with pure CuO nanoparticles. The initial discharge capacity of the pure CuO nanoparticles and their nanocomposite are 785.2 mAh g−1 and 1043.3 mAh g−1 with reversible capacity retention of 392.1 mAh g−1 and 516.4 mAh g−1 after 45 cycles respectively. The excellent electrochemical performance of CuO/reduced graphene oxide nanocomposite can be attributed to their unique structures, which intimately combine the conductive graphene nanosheets network with uniformly dispersed CuO nanoparticles. [Copyright &y& Elsevier]

Abstract: Combining experimental and computational techniques can provide a better understanding of surface film formation processes that occur in the lithium-ion battery. In this paper, we show that this joint approach can provide a mechanistic understanding of the effect of oxygen in the reduction of propylene carbonate (PC). We perform FTIR analysis, inside a glove box, after conducting linear sweep voltammetry (LSV) from an open-circuit voltage (OCV) to selected potential regions; subtraction between two successive IR spectra has been made to identify the reduction products formed within each potential range. FTIR analysis in the potential range from OCV to −0.1 V, in conjunction with density functional theory (DFT) calculations, confirm the formation of solvated Li2CO3 and (PC)2LiOC(O)OCH(CH3)CH2OLi(PC) due to PC reduction. Our experimental results and DFT calculations suggest that in the potential range from OCV to 1.6 V, PC, in the presence of O2, can easily decompose by the superoxide ion through a nucleophilic attack at the ethereal carbon atom. [Copyright &y& Elsevier]

Abstract: Different ionic liquids based on the 1-butyl-1-methylpyrrolidinium cation are added as a flame-retarding additive to a standard organic electrolyte, and their influences on the cycling performance and thermal stability of lithium-ion cells are investigated. The self-extinguishing time and DSC results demonstrate that the addition of the ionic liquids to the base electrolyte is effective in reducing the flammability of the electrolyte solution and improving the thermal stability of the cell. Among the ionic liquids evaluated in this study, 1-butyl-1-methylpyrrolidinium hexafluorophosphate was the most desirable flame-retarding additive for achieving the best cycling performance of lithium-ion cell. [Copyright &y& Elsevier]

Abstract: Magnetite (Fe3O4)/carbon core–shell nanotubes have been successfully synthesized by partial reduction of monodispersed hematite (Fe2O3) nanotubes with carbon coating. Fe2O3 is completely converted to Fe3O4 during the reduction process and a thin carbon layer is continuously coated on the surface of Fe3O4 with the nanotube morphology reserved. The Fe3O4/carbon core–shell nanotubes exhibit superior electrochemical properties as anode material for lithium-ion batteries compared with the Fe2O3 and Fe3O4 nanotubes. The Fe3O4/carbon core–shell nanotubes electrode shows a large reversible capacity up to 938 mAh g−1 as well as improved cycling stability and excellent rate capability. The promising anode performance of the Fe3O4/carbon core–shell nanotubes can be attributed to their tubular morphology and continuous carbon coating, which provide improved structural stability and fast charge transport. [Copyright &y& Elsevier]

Abstract: Tin oxide (SnO2)/graphene composite is synthesized via a simple wet chemical method using graphene oxide and SnCl2·2H2O as raw materials. Graphene of high reduction degree in the composite can provide high conductivity and large-current discharge capacity. SnO2 nanoparticles with dimension around 5 nm are uniformly distributed on the graphene matrix. The SnO2/graphene composite exhibits outstanding electrochemical performance such as high reversible capacities, good cycling stability and excellent high-rate discharge performance. The initial discharge and charge capacities are 1995.8 mAh g−1 and 1923.5 mAh g−1, respectively. After 40 cycles, the reversible discharge capacity is still maintained at 1545.7 mAh g−1 at the current density of 1 A g−1, indicating that the composite is a promising alternative anode material used for high-storage lithium ion batteries. [Copyright &y& Elsevier]

Abstract: Reduction of the charging time for batteries is a crucial factor in the promotion of consumer interest in the commercialization of electric vehicles (EVs). Fast charging methods for EVs are therefore important to create and understand; however, fast charging is not tolerated by all lithium-ion chemistries because it typically affects the battery functionality and accelerates its aging mechanisms. A fast charging technique is proposed in this paper, and the results of extensive testing on a high power lithium iron phosphate cell subjected to the method are reported. The evaluation characterized the cell's capacity fade, cycle life, and energy efficiency with respect to the U.S. Advanced Battery Consortium (USABC) goals. The proposed charging algorithm permits a full recharging of the cell (0–100% SOC) in approximately 20 min, even after 4500 cycles are reached. The cycling scheme is characterized by high current discharges that reach specific powers of 400 W kg−1. The results show that the proposed fast charging technique does not introduce any significant degradation effects on the cell and is energy efficient; they also show that performance is lost due to capacity fade rather than an increase in internal resistance. [Copyright &y& Elsevier]

Abstract: Li3V2(PO4)3/reduced graphene oxide (designated as Li3V2(PO4)3/rGO) and Li3V2(PO4)3/reduced modified graphene oxide (designated as Li3V2(PO4)3/rmGO) nanocomposites have been synthesized by a solvothermal method, followed by post-heat treatment at 800 °C, and explored as cathodes in lithium-ion cells. Lamellar GO sheets were modified with cetyltrimethylammonium bromide (CTAB) to form mGO with good dispersibility. The Li3V2(PO4)3/rGO (∼350 nm particles) and Li3V2(PO4)3/rmGO (∼200 nm particles) nanocomposite cathodes display discharge capacities of, respectively, 170 and 186 mA h g−1 at 0.1 C rate and 118 and 135 mA h g−1 at 10 C rate between 3.0 and 4.8 V. The higher discharge capacity and rate capability of Li3V2(PO4)3/rmGO compared to Li3V2(PO4)3/rGO are ascribed mainly to the smaller particle size of Li3V2(PO4)3 and the tight contact between the Li3V2(PO4)3 nanoparticles and the rmGO sheets. The tight contact enables fast electron transport through the underlying rmGO sheets to Li3V2(PO4)3 nanoparticles. [Copyright &y& Elsevier]

Abstract: The design of predictive, electrochemical, Li-ion battery models and the use of model-order reduction techniques to extract low-order models enables researchers to address problems related to model-based control, estimation, aging, and life-cycle prediction. This paper presents a novel approach to the design and parametrization of a reduced-order model characterizing the dynamic voltage response of a Li-ion cell. The model is based on the assumption of uniform active material utilization and includes prediction of the ionic concentration and potential dynamics in the liquid phase, which significantly affects the voltage response for high currents. A model-order reduction procedure based on the Pade approximation method is used to reduce the partial differential equation model to a low-order system of ordinary differential equations. Systematic methods are proposed to identify the electrochemical parameters that govern power and capacity prediction, as well as their temperature dependence. The procedure is based on carefully designed experiments that isolate the influence of small groups of parameters on the voltage output, utilizing complete cell data for model identification almost entirely in place of half-cell characterization. Finally, an extensive validation with experimental data illustrates the ability of the model to accurately predict the cell voltage. [Copyright &y& Elsevier]

Abstract: Na3V2(PO4)3 of the rhombohedral NASICON structure has been prepared via solid state carbothermal reduction reaction assisted by mechanochemical activation. As a cathode material for hybrid lithium ion batteries, Na3V2(PO4)3 exhibits an initial specific discharge capacity of 114.2 mAh g−1 in the voltage range between 2.5 V and 4.6 V, with a long discharge plateau near 3.7 V versus lithium metal. Approximately 3% of the discharge specific capacity is lost over the first 3 cycles at a current rate of 0.1 C. Then, the capacity appears to stabilize with the discharge specific capacity retention of 97.4% over the following 97 cycles. The material also exhibits good rate performance. Reversible capacities of 107.0 mAh g−1 at a 1 C rate, 100.5 mAh g−1 at 5 C and 84.4 mAh g−1 at 10 C have been obtained. The preliminary results prove that Na3V2(PO4)3 is a new promising material for hybrid lithium ion batteries. [Copyright &y& Elsevier]

Abstract: The detailed isothermal electrochemical model for a lithium ion cell comprises of 10 coupled partial differential equations (PDEs). It is computationally intensive to use this model for detailed parameter estimation, battery packs, battery management system algorithms, calendar or cycle life predictions etc. This work describes a reduced order model framework, which reduces the detailed model PDEs, to a manageable set of ordinary differential equations (ODEs), which can be used for the above applications. Volume averaging PDEs yield ODEs. Hence volume averaging is the basic method used for model reduction. The gradient or profile information lost on volume averaging is recovered through profile based approximations. For the lowest order reduced order model (ROM), a uniform reaction rate, quadratic electrolyte concentrations and quartic solid phase concentrations are assumed. In this ROM only 5 linear ODEs are solved, and the rest are nonlinear algebraic evaluations. When compared with the detailed electrochemical model of a lithium ion cell, this ROM gives negligible error at nominal currents and a maximum error of about 3% at high currents, for a typical commercial cell. [Copyright &y& Elsevier]

Abstract: Graphene nanosheets (GNS) wrapped SnCo alloy nanoparticles are prepared by a chemical reduction method on an ice water bath. SnCo nanoparticles are dispersed uniformly on GNS and their particle sizes are around 8-12 nm, which are substantially smaller than the pristine SnCo particles (∼80-180 nm) prepared in the absence of GNS. The GNS-SnCo composite is fabricated as an anode material for lithium ion batteries. It shows a distinguished higher-than-theoretical capacity of 1117 mAh g−1 at 72 mA g−1, which is larger than bare GNS (727 mAh g−1) or Sn-Co particles (599 mAh g−1). Moreover, the GNS-SnCo composite shows a good rate performance at a large current of 720 mA g−1. A high capacity of 922 mAh g−1 is retained with more stable cycle life than that at a small current. These improved cycling performances are attributed to the complimentary effect of three elements. The mechanical stability of Sn upon cycling is improved by the presence of robust and electrically conductive GNS and the alleviated function of inactive cobalt element. The agglomeration of GNS is also hindered by the spacing effect of SnCo nanoparticles among neighboring GNS materials. [Copyright &y& Elsevier]

Abstract: A facile approach to the surface reduced graphene oxide (rGO) modification of micro-nano structured vanadium oxides composites are developed as cathode materials of lithium ions batteries (LIBs) and supercapacitors (SCPs) for the first time. The as-prepared V2O5–rGO and VO2–rGO composites exhibit remarkably enhanced cycling performance when being used as cathode materials in LIBs and SCPs, respectively. The uniform coating of graphene around the surface of vanadium oxides ensures good close electrical contact, therefore higher specific capacity and enhanced cycling performance than pure VO2 and V2O5 electrodes. Meanwhile, the cycling performance enhancement and capacity decay mechanism are presented, which is not only important to design electrode materials in LIBs and SCPs, but also extendable to the design and fabrication of other functional materials for energy storage and transfer systems. [Copyright &y& Elsevier]

Abstract: It is accepted that the reduction of iodine species in non-aqueous solvents occurs through one-electron or two-electron processes below roughly 3.5 V vs. Li/Li+. In some iodine solutions, the molecular complexation of iodine with the organic solvent proceeded via a charge–transfer interaction. Reduction of iodine in non-aqueous solvents having S:glyph name="dbnd" />O groups, as well as interactions of iodine molecules with these solvents, were studied. Iodine molecules associated with dimethyl sulfoxide (DMSO), tetramethylene sulfoxide (TMSO), and trimethyl phosphate (TMP) showed anomalous reduction above+1.0 V vs. NHE. We demonstrated the operation of lithium–iodine batteries using DMSO, TMSO and TMP near 4.0 V vs. Li/Li+. [Copyright &y& Elsevier]

Abstract: Li3V2(PO4)3 nanocrystals (5–8 nm) embedded in a nanoporous carbon matrix attached onto reduced graphene oxide nanosheets (LVP-NC@NPCM@rGO) are synthesized by a facile approach. The rGO sheets not only form the interconnected conducting scaffold to enhance the charge transfer but also act as the heterogeneous nucleation site to facilitate the growth of nanograins of LVP. The nanoporous carbon acts as the nanocontainer to enhance the electrolyte/active material interaction and also inhibit the grain growth of Li3V2(PO4)3. This leads to the fast kinetics of the Li ion transfer and the excellent cathode performance, especially at high current densities. Binder-free cathodes can be prepared based such LVP-NC@NPCM@rGO sample, which shows high specific capacities, stable cyclabilities and excellent rate capabilities in the voltage ranges of 3.0–4.3 and 3.0–4.8 V. [Copyright &y& Elsevier]

Abstract: Li3V2(PO4)3/C cathode material is synthesized by a carbon-thermal reduction method using polyvinyl alcohol as carbon source at 700°C. The Li3V2(PO4)3/C electrode presents a high initial discharge capacity of 84.3, 111.1, 128.7, 129.2 and 132.1mAhg−1 at −20, 0, 25, 40 and 65°C between 3.0 and 4.3V, and 118.9, 132.1, 187.6, 180.3 and 172.2mAhg−1 between 3.0 and 4.8V at 0.1C, respectively. However, the electrode only delivers small discharge capacities at −20°C at 10C rate. The capacity fade at low temperatures is mainly attributed to the reduced ionic and electronic conductivity of the electrolyte, the increased impendence of solid electrolyte interface (SEI) and charge-transfer resistance on the electrolyte–electrode interfaces. At higher temperatures, the capacity increases with increasing temperature between 3.0 and 4.3V, but decreases between 3.0 and 4.8V. In the potential range of 3.0–4.8V, the larger crystal structural distortion and non-uniformity of SEI layer at high temperatures may be the main reasons for the capacity loss. [Copyright &y& Elsevier]

Abstract: In this paper, effective and systematic steps in the mathematical simplification and reduction of physics-based lithium-ion (Li-ion) battery models to improve computational efficiency will be presented. The battery model used for simulations is an isothermal model proposed by Newman and Tiedemann and Doyle et al. which incorporates the concentrated solution theory, the porous electrode theory, and the variations in electronic/ionic conductivities and diffusivities. The simplified model is formulated by exploiting the nature of the model and the structure of the governing equations. Simulations show that the simplified model can reduce computational time significantly while still retaining the accuracy compared to the full-order rigorous model. [Copyright &y& Elsevier]

Abstract: Strontium titanate nanoparticles have been synthesized using a combination of sol-precipitation and hydrothermal techniques for subsequent testing as an anode material for lithium-ion batteries. The potentials associated with lithiation are 0.105V and 0.070V vs. Li/Li+ and 0.095V and 0.142V vs. Li/Li+ during de-lithiation. These potentials are significantly lower than the 1.0V to 1.5V vs. Li/Li+ typically reported in the literature for titanates. In an attempt to improve the lithiation and de-lithiation kinetics, as well as capacity retention, SrTiO3 nanoparticles were platinized using a photoinduced reduction of chloroplatinic acid. No significant changes in the morphology or crystal structure of the platinized nanoparticles were observed as a result of the reduction reaction. The voltage profile, charge and discharge kinetics, and cyclability of the platinized SrTiO3 nanoparticles are compared to that of the non-platinized SrTiO3 nanoparticles. [Copyright &y& Elsevier]

Abstract: The composite [Sn–BPO4/xC] to be used as negative electrode material for the storage of electrochemical energy was obtained by dispersing electroactive tin species onto a BPO4 buffer matrix by carbothermal reduction of a mixture of SnO2 and nanosized BPO4. This composite material was thoroughly characterized by X-ray diffraction, Scanning Electron Microscopy, 119Sn Mössbauer spectroscopy and Raman spectroscopy. The electrochemical tests of this new material highlight its very interesting electrochemical properties, i.e., a discharge capacity of 850mAhg−1 for the first cycle and reversible capacity around 585mAhg−1 at C/5 rate. These electrochemical performances are attributed to the very high dispersion and stabilisation of tin metal particles onto the BPO4 matrix. The irreversible capacity observed for the first charge/discharge cycle is due the reduction of interfacial SnII species and to the passivation of the anode surface by liquid electrolyte decomposition (formation of the SEI layer). [Copyright &y& Elsevier]

Abstract: The electrochemical performance of a composite of nano-Si powder and a pyrolytic carbon of polyvinyl chloride (PVC) with carbon nanofiber (CNF) was examined as an anode for solid-polymer lithium-ion batteries. Nano-Si powder was firstly coated with carbon by pyrolysis of PVC and then mixed with CNF (referred to as Si/C@CNF) using a rotation mixer. The composite exhibited good cycling performance, but suffered from a large irreversible capacity loss of which the retention was less than 60%. In order to reduce the loss, a thin lithium sheet was attached to the Si/C@CNF electrode surface as a reducing agent. The irreversible capacity of the first cycle was lowered to as much as 0mAhg−1 and after the third cycle, the lithium insertion and extraction efficiency was almost 100%. A reversible capacity of more than 1000mAhg−1 was still maintained after 40 cycles. [Copyright &y& Elsevier]

Abstract: The reduction mechanism of ethylene sulfite (ES) in propylene carbonate (PC) based electrolyte is investigated using density functional theory in gas phase. Based on the electron affinity energy and lowest unoccupied molecular orbital (LUMO) energy, it can be known that free ES is reduced most easily compared with ES-Li+ and ES-Li+-PC, generating SO2 and propanal. However, the binding energy of ES-Li+ and ES-Li+-PC is quite negative, indicating that both of them are more possible in electrolyte solution than the free ES. The reductive decomposition products of ES-Li+ and ES-Li+-PC are OSO2Li, OSO2Li-R and ethylene. OSO2Li and OSO2Li-R are the main compositions of the solid electrolyte interphase film on the anode of lithium ion battery, which inhibits the reductive decomposition of PC. These calculations provide a detailed explanation on the experimental phenomena. [Copyright &y& Elsevier]

Abstract: Core–shell structured, carbon-coated, nano-scale Cu6Sn5 has been prepared by a modified carbothermal reduction method using polymer coated mixed oxides of CuO and SnO2 as precursors. On heat treatment, the mixture oxides were converted into Cu6Sn5 alloy by carbothermal reduction. Simultaneously, the remnants carbon was coated on the surface of the Cu6Sn5 particles to form a core–shell structure. Transmission electron microscope (TEM) images demonstrate that the well-coated carbon layer effectively prevents the encapsulated, low melting point alloy from out flowing in a high-temperature treatment process. Core–shell structured, carbon coated Cu6Sn5 delivers a reversible capacity of 420mAhg−1 with capacity retention of 80% after 50 cycles. The improvement in the cycling ability can be attributed to the fact that the carbon-shell prevents aggregation and pulverization of nano-sized tin-based alloy particles during charge/discharge cycling. [Copyright &y& Elsevier]