Anode Materials for Lithium Ion Batteries

Functional electrically conductive fabric with acceptable mechanical properties, which could be applied in electromagnetic shielding, was developed. Conductive cotton fabrics (cotton/PANI, cotton/Mn, cotton/Cu, and cotton/Co) were prepared by in situ chemical oxidative polymerization for (cotton/PANI) and pad dry curing method was used for nanometals application. The Nano size of the metals and polyaniline inclusion were proven through both Dynamic Liquid Scattering (DLS) and X-ray diffraction (XRD) which showed an increase in crystallite density in unit space and the nano-particles ranged from 100-200 nm. The effect of gamma irradiation on different treated cotton fabrics was investigated. The mechanical properties against irradiation dose showed an improvement up to 40 kGy, for all treated fabrics. On the other hand, Young's modulus for untreated cotton recorded the lowest value, while cotton/Co recorded the highest one. Moreover, both AC (Alternating Current) and DC (Direct current) conductivities values can be calculated. In DC conductivity cotton/PANI was found to be more conducive than the remainder of the treated fabric by surface met-allization with transition metals; while in AC conductivity cotton/Mn was found to be more conducive than the rest of the treated samples. The conductivity value increases by increasing the gamma irradiation dose for cotton/PANI fabric. Also, g-factor values can be estimated from ESR signals and vary from 0.009 up to 0.059 for conductive

Anode materials of rechargeable lithium-ion batteries have been developed towards the aim of high
power density, long cycle life, and environmental benignity. As a promising anode material for high
power density batteries for large scale applications in both electric vehicle and large stationary power
supplies, the spinel Li4Ti5O12 anode has become more attractive for alternative anodes for its relatively
high theoretical capacity (175 mA h g1), stable voltage plateau of 1.5 V vs. Li/Li+, better cycling
performance, high safety, easy fabrication, and low cost precursors. This perspective first introduces
recent studies on the electronic structure and performance, synthesis methods, and strategies for
improvement including carbon-coating, ion-doping, surface modifications, nano-structuring and
optimization of the particle morphology of the Li4Ti5O12 anode. Furthermore, practical applications of
the commercial spinel lithium-ion batteries are demonstrated. Finally, the future research directions and
key developments of the spinel Li4Ti5O12 anode are pointed out from a scientific and an industrial point of
view. In addition, the prospect of the synthesis of graphene–Li4Ti5O12 hybrid composite anode materials
for next-generation lithium-ion batteries is highlighted.

Lithium-ion batteries (LIBs) have revolutionized the portable electronic devices and electric vehicles (EV) and because of this huge demand, it is important to meet high power, high specific energy, and long cycle life. All mentioned characteristics are directly related to the choice of anode and cathode electrodes. Currently, graphite is used as anode, while lithium cobalt oxide serves as cathode dominantly. Although graphite can deliver ~ 370 mA h g-1 capacity without significant capacity decay for several cycles, however it is not enough to fulfill the requirements for many applications. Silicon with the theoretical capacity of about 10 times higher than graphite is a promising anode. However, this material suffers from huge volume expansion during cycling in addition to its intrinsic low conductivity. From the cathode viewpoint, the need for materials with less cobalt content is necessary. The resources for cobalt element is very limited while the price of cobalt increasing. Furthermore, cobalt is known as toxic element. Therefore, substitution of cobalt with other elements such as manganese and nickel is necessary. Lithium nickel manganese cobalt oxide (NMC) cathode family materials are introduced following this idea. Here in this thesis, two different approaches are introduced to harness the problems associated with silicon anodes. The first approach is the core/shell design and the second one is the silicon/graphite nanocomposite with tailored structure and engineered voids. Both of these designs can be synthesized easily without complicated synthesis steps and harmful chemicals. They have the potential of being commercialized and they do not need expensive equipment. The silicon anodes have been tested successfully in the half-cell coin cells. As for the cathode side, two different members of NMC family materials (NMC333 and NMC532) have been tested. To enhance their electrochemical properties and rate capabilities, a facile surface modification using phosphoric acid was employed. This technique resulted in the formation of thin lithium phosphate coating around the particle. The electrodes performed very well in half-cell configuration. It is expected by utilizing the proposed cathode and anode materials in full-cell set up, a high performance battery with fast charge ability is obtained.

En esta contribución, se realiza un análisis exhaustivo de la empresa mixta conformada por Yacimientos de Litio Bolivianos (YLB) y ACI Systems Alemania GmbH (ACISA) para la producción de hidróxido de litio a partir de salmueras residuales del Salar de Uyuni. El ensayo se divide en tres partes. En la primera, se muestran las perspectivas distintas de las socias en términos de visión y alcance de la asociación, así como las omisiones y distorsiones de información por parte de las mismas en relación con el Decreto Supremo No. 3738 de creación de la empresa pública YLB-ACISA promulgado el pasado 7 de diciembre de 2018.  Adicionalmente, se consideran aspectos relativos a las salmueras residuales emergentes de un proceso de producción anterior de carbonato de litio altamente ineficiente, junto con una serie de conflictos de intereses que empañan seriamente el proceso de selección de ACISA como socia de YLB en el  nuevo emprendimiento. En la segunda, además de encontrar que YLB no podrá asumir ninguna decisión favorable a los intereses particulares de Bolivia sin contar con el apoyo de su “socia alemana” se examina las ocho razones por las cuales es posible argumentar que la empresa mixta YLB-ACISA es “entreguista” y atentatoria a los intereses nacionales. Finalmente, en la tercera, se demuestra la ilegalidad del DS 3738 por cuanto vulneraría el principio de participación 100% estatal de YLB en las dos primeras fases de la estrategia de industrialización del litio del gobierno, establecido en las Leyes de Minería y Metalurgia y de Creación de YLB, así como el Artículo 224 de la primera ley citada anteriormente bajo el argumento falaz de que el hidróxido de litio producido a partir de salmuera residual es un producto industrializado.

Due to their high specific surface area and advanced properties, TiO2 nanotubes (TiO2 NTs) have a great significance for production and storage of energy. In this paper, TiO2 NTs were synthesized from anodization of Ti-6Al-4V alloy at 60 V for 3 h in fluoride ethylene glycol electrolyte by varying the water content and further annealing treatment. The morphological, structural, optical and electrochemical performances of TiO2 NTs were investigated by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), UV-Visible spectroscopy and electrochemical characterization techniques. By varying the water content in the solution, a honeycomb and porous structure was obtained at low water content and the presence of (α + β) phase in Ti-6Al-4V alloy caused not uniform etching. With an additional increase in water content, a nanotubular structure is formed in the (α + β) phases with different morphological parameters. The anatase TiO2 NTs synthesized with 20 wt% H2O shows an improvement in absorption band that extends into the visible region due the presence of vanadium oxide in the structure and the effective band gap energy (Eg) value of 2.25 eV. The TiO2 NTs electrode also shows a good cycling performance, delivering a reversible capacity of 82 mAh.g−1 (34 μAh.cm−2.μm−1) at 1C rate over 50 cycles.

Manganese cobaltite (MnCo 2 O 4) is currently under screening as a high performance supercapacitor electrode owing to its high theoretical capacitance, improved electrical conductivity and long term cyclic stability. Herein, we report synthesis of MnCo 2 O 4 cuboidal microcrystals using hydrothermal method and compare its performance with its flakes prepared by solid combustion process. Crystal structure, surface properties, and electrochemical properties of the flakes are studied using X-ray diffraction, gas adsorption, field emission scanning electron microscopy, cyclic voltammetry, galvanostatic charge edischarge cycling, and electrochemical impedance spectroscopy. The electrochemical properties of MnCo 2 O 4 flakes synthesized using hydrothermal synthesis are superior to that synthesized using the solid combustion process. Electrochemical properties of the cuboidal microcrystals (~specific capaci-tance, C S ~600 F g À1 @ 0.5 A g À1) are superior to those synthesized by the combustion process (C S ~128 F g À1) due to improved faradic utilization of active surface area, layered cuboidal morphology, faster OH À ion penetration owing to higher diffusion coefficient, and larger voltage range available for elec-trochemical reaction.

A method was developed to synthesize ferromagnetic nickel core/carbon shell nanotubes (Ni/CNTs) by
chemical vapor deposition using Pauli paramagnetic lanthanum nickel (LaNi5) alloy both as a catalyst and
as a source for the Ni-core. The Ni-core was obtained through oxidative dissociation followed by
hydrogen reduction during the catalytic growth of the CNTs. Transmission electron microscopy (TEM),
selected area electron diffraction (SAED) and X-ray diffraction (XRD) analyses reveal that the Ni-core
exists as a face centered cubic single crystal. The magnetic hysteresis loop of Ni/CNTs particle shows
increased coercivity (446.42 Oe) than bulk Ni at room temperature. Furthermore, the Ni/CNTs core/shell
particles were investigated as anode materials in lithium-ion batteries. The Ni/CNTs electrode delivered a
high discharge capacity of 309 mA h g
1 at 0.2 C, and a stable cycle-life, which is attributed to high
structural stability of Ni/CNTs electrode during electrochemical lithium-ion insertion and de-insertion
redox reactions.

Although lithium is an abundant element, there are only a few places where it can be mined in sufficient concentrations and under acceptable mining conditions. Salt deposits are the main source of lithium, accounting for about 60% of the world's known reserves. Approximately 78% of these lithium brines are found underground in salt flats, dried-up salt lakes with a typical lithium content of 0.2 to 1.5 g/l. Other brine deposits are concentrates from salt lakes, are of geothermal origin, are found in petroleum reservoirs, are residues from the extraction of sodium chloride from seawater, or are discharges from seawater desalination plants. The remaining lithium resources are found in lithium-bearing igneous ores and lithium clays. The realization of a new lithium mining project is a challenging task, and many projects never reach the production phase due to a lack of comprehensive planning across all project phases, starting with technical advice in the concept and exploration phases, reliable resource identification and certification, detailed engineering with bankable feasibility studies, and thoroughly planned commissioning. The ever-increasing demands for socially and environmentally sustainable lithium production raise the bar even higher for mining companies and increase the risk of management mistakes in the early stages and thus the economic failure of the project. This document presents a summary of the engineering and consulting services of K-UTEC Salt Technologies required for the different project phases of typical lithium mining and lithium salt production projects.

In this contribution we report on the influence of Mn doping on various physical properties of
Li4Ti5
xMnxO12 (x ¼ 0, 0.005, 0.025, 0.01, 0.05, 0.075, 0.1 and 0.2). Spinel-type (space group Fd3m, a ¼
0.8358 nm) Li4Ti5
xMnxO12 was produced as highly uniform and polyhedral shaped powder in a size
range between 200 and 400 nm. The crystal structure of Li4Ti5
xMnxO12, the morphology and the Mnion
distribution have been investigated by X-ray diffraction (XRD) and scanning and transmission
electron microscopies (SEM and TEM). The oxidation state of Mn and the conductivity behavior of Mnsubstituted
Li4Ti5
xMnxO12 samples have been studied using multi-frequency electron paramagnetic
resonance (EPR). Mn is incorporated as Mn2+, and these ions increase the conductivity of Li4Ti5O12; a
conductivity value of 0.48  10
8 S cm
1 was measured for Li4Ti5
xMnxO12 with x ¼ 0.075, which is tenfold
larger than that of undoped Li4Ti5O12.

La extracción del litio de las salmueras de salares es la práctica más competitiva del mercado por sus relativamente bajos costos de inversión y operación, considerando que la mayor parte de los yacimientos importantes de litio en salinas a nivel mundial se encuentran en salmueras de la zona denominada “triángulo del litio”, localizado en territorios de Argentina (salares de la puna Jujeña y Salteña, y norte de Catamarca), Bolivia (Salares de Uyuni y Coipasa) y Chile (Salares de Atacama y Maricunga). Debido a la escasez de agua en las regiones de producción de litio, un desafío para la industria es el desarrollo de metodologías ecoeficientes que requieren menos agua. En este contexto, la empresa K-UTEC Salt Technologies ha desarrollado un proceso innovador y ecoeficiente para extraer hidróxido de litio de alta calidad, una sal requerida para la producción de baterías de litio, minimizando el desgaste de agua y además evitando el uso de sustancias químicas nocivas para el amiente.

Nickel ferrite (NiFe 2 O 4) has been previously shown to have a promising electrochemical performance for lithium-ion batteries (LIBs) as an anode material. However, associated electrochemical processes, along with structural changes, during conversion reactions are hardly studied. Nanocrystalline NiFe 2 O 4 was synthesized with the aid of a simple citric acid assisted sol−gel method and tested as a negative electrode for LIBs. After 100 cycles at a constant current density of 0.5 A g −1 (about a 0.5 Crate), the synthesized NiFe 2 O 4 electrode provided a stable reversible capacity of 786 mAh g −1 with a capacity retention greater than 85%. The NiFe 2 O 4 electrode achieved a specific capacity of 365 mAh g −1 when cycled at a current density of 10 A g −1 (about a 10 Crate). At such a high current density, this is an outstanding capacity for NiFe 2 O 4 nanoparticles as an anode. Ex-situ X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) were employed at different potential states during the cell operation to elucidate the conversion process of a NiFe 2 O 4 anode and the capacity contribution from either Ni or Fe. Investigation reveals that the lithium extraction reaction does not fully agree with the previously reported one and is found to be a hindered oxidation of metallic nickel to nickel oxide in the applied potential window. Our findings suggest that iron is participating in an electrochemical reaction with full reversibility and forms iron oxide in the fully charged state, while nickel is found to be the cause of partial irreversible capacity where it exists in both metallic nickel and nickel oxide phases.

Micro-sized Li4Ti5xBixO12(0x0.15) materials are synthesized using a simple solid state method in air. The structural, morphological, and electrochemical characteristics of Bi-doped lithium titanates and pristine samples are methodically analyzed by X-ray diffraction (XRD), Raman spectroscopy,field
emission-scanning electron microscopy (FE-SEM), and electrochemical impedance spectroscopy (EIS). The XRD and Raman spectroscopy results demonstrate that bismuth-doping do not alter the spinel structure and good crystalline materials are synthesized. The FE-SEM images show that all samples
possess the same morphological characteristics, with a particle size distribution of 0.5-1mm. The electrochemical cycling testing reveals that the Li4Ti4.9Bi0.10O12sample exhibits discharge capacities of 205.4 mAh/ g, 160.8 mAh/ g, and 135.4 mAh/ g after 50 cycles at 1C, 5C, and 10C-rates, respectively. The differential capacity curves suggest that the Li4Ti4.9Bi0.10O12 sample has a weaker polarization effect than the other samples. The EIS measurements imply that the Li4Ti4.9Bi0.10O12 sample possesses a high electronic conductivity and lithium ion diffusivity, which demonstrate that this new Li4Ti4.9Bi0.10O12 material would be a good candidate as an anode for lithium ion batteries.

Currently, lackluster battery capability is restricting the widespread integration of Smart Grids, limiting the long-term feasibility of alternative, green energy conversion technologies. Silicon nanoparticles have great conductivity for applications in rechargeable batteries, but have degradation issues due to changes in volume during lithiation/delithiation cycles. To combat this, we use electrochemical deposition to uniformly space silicon particles on graphene sheets to create a more stable structure. We found the process of electrochemical deposition degraded the graphene binding in the electrode material, severely reducing charge capacity. But, the usage of mechanically mixing silicon particles with grapheme yielded batteries better than those that are commercially available.

ithium is the third element on the periodic table and the first element in the alkali metal group it has atomic mass of 6.94 g/mol, an atomic radius of 1.33 Å, a melting point of 180.5 ℃ and a boiling point of 1342℃. With a density of just 0.534 g/cm 3 , lithium metal floats in water even as it reacts. Lithium has a hardness of 0.6 on the Mohr scale, is softer than talc (Mg Si O (OH)), the softest mineral on the Mohr scale (talc hardness = 1). Lithium is harder than carbon = 0.5, caesium =0.5, and sodium = 0.5 but softer than lead = 1.5 [1]. Lithium has the highest specific heat capacity (at 25 ℃) of any solid element at 3.56 J/g K. Lithium is the most polarising of all the alkali metals and more electronegative than H so it can accumulate chemical energy very efficiently. At a pressure in excess of 40 gigapascals (400,000 atmospheres) lithium becomes a superconductor There are several radioisotopes of lithium ( 4 Li to 12 Li). Their half-lives range from 9 x 10 -23 s for 4 Li to 8 x 10 -1 s for 8 Li. Naturally occurring lithium exists as the tow stable isotopes 6 Li (at 7% abundance) and Li (at 93% abundance) . Lithium has a single valence electron on its outer shell which is freely given up for reaction to from a variety of compounds . The highly reactive nature of lithium (the least reactive of the alkali metals) towards oxygen, a trait it shears with other group 1 alkali metals, means that it never occurs as a pure metal in nature, instead, it occurs as various salts and minerals. The comical history of lithium began with the characterisation of the aluminosilicate minerals petalite (LiAlSi4O10) and spodumene (LiAlSi2O6). They were discovered at the start of the 18 th century be the Brazilian statesman and naturalist Josè Bonifacio de Andrade e Silva the island of Utö, near Stockholm, Sweden . In 1817 the Swedish chemist Johan August Arfwedson discovered a previously unknown element in the new mineral petalite. Arfwedson was working at the time for another Swedish chemist, Baron Jöns Jacob Berzelius. Lithium, according to the author Berzelius (1964) (who coincidentally sheares the same name as Jöns Jacob Berzelius) formed compounds similar to those of sodium and potassium , although lithium's carbonate and hydroxide forms are less soluble in water and alkaline . Together the tow chemists named the mysterious element lithion/litaina from the Greek for stone. Arfwedson went on to discover lithium in lepidolite (K (Li, Al)3(Al, Si,Rb)4O10(F, OH)2). In 1818 Christian Gottlieb Gmelin a colleague of Arfwedson was the first to observe that lithium salts, when exposed to flames, gave off an intense red flame . Although Arfwedson had discovered the element he never managed to isolated pure metallic lithium. In 1821, the English chemist William Thomas Brand, a colleague of Sir Humphary Davy, obtianed lithium by the electrolysis of lithium oxide . In 1855, the German chemist Robert Wilhelm Eberhard Bunsen and English chemist Augustus Matthiessen isolated lithium from lithium chloride be electrolysis . Their production method was later commercialised by the German company Matllgesellschaft AG (1923), who produced metallic L lithium electrolytically from a mixture of 55% lithium chloride and 45% potassium chloride at a temperature of 450℃ [9].

Self-organized Titanium dioxide (TiO2) nanotubes grown on Ti grid acting as anode for Li-ion microbatteries were prepared via an electrochemical anodization. By tuning the anodization time, the morphology and length of the nanotubes were investigated by scanning electron microscope. When the anodization time reached 1.5 h, the TiO2 nts/Ti grid anode showed a well-defined nanotubes, which are stable, well-adherent ∼90 nm with a length of 1.9 ± 0.1 µm. Due to their high surface utilization, surface area, and material loading per unit area, TiO2 nts/Ti grid anode using polymer electrolyte exhibited a high areal capacity of 376 µAh cm −2 at C/10 rate and a stable discharge plateau at 1.8 V without using a polymer binder and conductive additive. The storage capacity of the TiO2nts/Ti grid after 10 cycles is 15 times higher compared to previous reports using planar Ti foils.

In this study we have investigated the electrochemical properties of hollow silicon nanospheres encapsulated with a thin carbon shell, HSi@C, as a potential candidate for lithium-ion battery anodes. Hollow Si nanospheres are formed using a templating method which is followed by carbon coating via carbonization of a pyrrole precursor to form HSi@C. The synthesis conditions and the resulting structure of HSi@C have been studied in detail to obtain the target design of hollow Si nanospheres encapsulated with a carbon shell. The HSi@C obtained exhibits much better electrochemical cycle stability than both micro-and nano-size silicon anodes and deliver a stable specific capacity of 700 mA h g-1 after 100 cycles at a current density of 2 A g-1 and 800 mA h g-1 after 120 cycles at a current density of 1 A g-1. The superior performance of HSi@C is attributed to the synergistic combination of the nanostructured material, the enhanced conductivity, and the presence of the central void space for Si expansion with little or no change in the volume of the entire HSi@C particle. This study is the first detailed investigation of the synthesis conditions to attain the desired structure of a hollow Si core with a conductive carbon shell. This study also offers guidelines to further enhance the specific capacity of HSi@C anodes in the future.

One-dimensional electrospun lead oxide nanofibers synthesized by a simple electrospinning technique. The prepared lead oxide nanofibers investigated by using TG/DTA, FTIR, Raman, X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analyzer, scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM-EDX), atomic force microscopy (AFM), Transmission electron microscopy (TEM), and impedance spectroscopy techniques. TG/DTA results confirmed the thermal behavior of the as-spun nanofibers. XRD, FTIR, and Raman spectra results, respectively, confirm the formation of pure orthorhombic crystalline phase and structural coordination of the lead oxide (β-PbO) nanofibers. The BET specific surface area of β-PbO nanofibers sample is found to be 51.23 m² g⁻¹. SEM and AFM micrographs showed the formation of β-PbO nanofibers with a diameter of 85-300 nm. The impedance measurements of lead oxide nanofibers as a function of temperature, 25-150 oC, was evaluated by analyzing the measured impedance data using the winfit software. The electrical conductivity of the lead oxide (β-PbO) nanofibers evaluated by analyzing the measured impedance data using the winfit software is found to be 5.68 x 10⁻⁶ S cm⁻¹ at 150 oC. Also, an activation energy (Ea) for the migration of the charge carrier evaluated from the temperature dependence of conductivity plot is found to be 0.27 eV. The temperature dependence AC conductivity of β-PbO nanofibers was evaluated using the measured impedance data and sample dimension. The observed variation of high-frequency AC conductivity attributed to the hopping electrons between the adjacent sites

Structural characterization and impedance studies of PbO nanofibers synthesized by electrospinning technique. Available from: https://www.researchgate.net/publication/315589537_Structural_characterization_and_impedance_studies_of_PbO_nanofibers_synthesized_by_electrospinning_technique [accessed Jun 5, 2017].

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of TMO-NPs by morphology control and carbon coating. [4] Yolk-shell nanostructures as anode materials are of more interest in resolving the problems associated with large volume change, low conductivity, and short diffusion path for Li + ion transport. [5] The simulation and experimental observations reveal that the confinement of TMO-NPs into carbon nanotubes (CNTs) with internal void gap is more flexible for allowing large volume expansion of TMO-NPs during the lithiation/delithiation process of LIBs. [4c,e,6] The encased TMO-NPs into CNTs can allow fast Li + ion transportation , prevent the aggregation of NPs, reduce the pulverization of active material , and limit the direct contact of TMO-NPs with the electrolyte for the formation of unstable SEI. [7] However, the smaller diameter and stiffness of the walls of CNTs cannot properly facilitate the Li + ion transport to TMO-NPs and internal void gap. [8] These inspire the researchers to explore the new synthetic methods for making the TMO-NPs encapsulated graphitic nanotubes (GNTs) with porous wall. [9] But the problem for the existed interesting yolk-shell system is that the nitrogen (N) or boron (B) doping of CNTs is not tuned for better activating the electron spin density between heteroatom and adjacent carbon atom for performance optimization, and also the encapsulated TMO-NPs are solid, which greatly impact their electrochemical property for developing high-performance LIB. To well address this issue, herein we report a general procedure for encapsulating hollow metal oxide (MO)-NPs into B, N co-doped graphitic nanotubes (MO@BNG (MO = CoO, Ni 2 O 3 , Mn 3 O 4) for boosting lithium-ion storage. Due to their integrated features including high surface area, good electrical conductivity, hollow active NPs with thin wall, and the indirect contact of metal oxide with electrolyte, the hollow MO@ BNG nanostructures are highly particular for boosting LIBs. The CoO@BNG composite shows a very large capacity of 1554 mA h g −1 at the current density of 96 mA g −1 , good rate capability (410 mA h g −1 at 1.75 A g −1), and high cycling stability with almost 96% storage capacity retention after 480 cycles. The present work gives the first example in introducing hollow CoO NPs with thin wall into BNG with large surface area for enhancing LIBs in the terms of storage capacity, rate capability, and cycling stability. Yolk-shell nanostructures have received great attention for boosting the performance of lithium-ion batteries because of their obvious advantages in solving the problems associated with large volume change, low conductivity, and short diffusion path for Li + ion transport. A universal strategy for making hollow transition metal oxide (TMO) nanoparticles (NPs) encapsulated into B, N co-doped graphitic nanotubes (TMO@BNG (TMO = CoO, Ni 2 O 3 , Mn 3 O 4) through combining pyrolysis with an oxidation method is reported herein. The as-made TMO@BNG exhibits the TMO-dependent lithium-ion storage ability, in which CoO@BNG nanotubes exhibit highest lithium-ion storage capacity of 1554 mA h g −1 at the current density of 96 mA g −1 , good rate ability (410 mA h g −1 at 1.75 A g −1), and high stability (almost 96% storage capacity retention after 480 cycles). The present work highlights the importance of introducing hollow TMO NPs with thin wall into BNG with large surface area for boosting LIBs in the terms of storage capacity, rate capability, and cycling stability. Lithium-Ion Batteries Rechargeable lithium-ion batteries (LIBs) are widely used as the most effective energy storage technology in consumer transportation and dominated portable electronic market for over two decades. [1] However, the biggest challenging issue of LIBs is that they still show the limited energy density and stability, rendering them difficult to be used in practical vehicles. [1b] The pristine transition metal oxide nanoparticles (TMO-NPs) are intriguing materials for LIBs due to their high theoretical storage capacity, [2] but their poor conductivity, low stability, large volume expansion during charge/discharge process, and depletion of electrolyte by the formation of thick solid electrolyte interface (SEI) lead to the well-known low capacity and also the rapid capacity decay, thus limiting their commercialization. [3] Great efforts have been devoted to optimizing the performance Adv. Mater. 2018, 1705441

Silicon alloys composed of silicon nanoparticles embedded in inert Cu-Al-Fe matrix phases were synthesized and encapsulated with reduced graphene oxide (rGO) nanosheets. Successful synthesis of the silicon alloys and their encapsulation with rGO were confirmed by X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopic analyses. The silicon alloy encapsulated with an optimal amount of rGO delivered an initial discharge capacity of 1140.7 mAh g À1 with good capacity retention and exhibited excellent rate capability. This superior performance could be attributed to the unique structure of silicon alloy encapsulated by rGO, which could effectively accommodate the large volume change during cycling and provide continuous electronic conduction pathway in the electrode.

a b s t r a c t Nanostructured Fe 3 O 4 nanoparticles were prepared by a simple sonication assisted co-precipitation method. Transmission electron microscopy, X-ray diffraction and BET surface area analysis confirmed the formation of ∼20 nm crystallites that constitute ∼200 nm nanoclusters. Galvanostatic charge-discharge cycling of the Fe 3 O 4 nanoaprticles in half cell configuration with Li at 100 mA g −1 current density exhibited specific reversible capacity of 1000 mAh g −1 . The cells showed stability at high current charge-discharge rates of 4000 mA g −1 and very good capacity retention up to 200 cycles. After multiple high current cycling regimes, the cell always recovered to full reversible capacity of ∼1000 mAh g −1 at 0.1 C rate.

It is well-known that silicon anodes experience large volume expansion (> 300%) when fully lithiated. By introducing engineered voids into a Si/C core-shell structure to form Si@void@C structure, volume expansion of Si@void@C particles can be minimized, thereby improving the cycle stability of the Si@void@C electrode. This study reveals that by adjusting charge/discharge protocols the cycle stability of the Si@void@C electrode can be further enhanced. It is shown that both lower and upper cutoff voltages during charge and discharge, respectively, have strong influence on the cycle stability of the Si@void@C electrode. These phenomena are interpreted based on volume expansion and shrinkage of the Si@void@C electrode as a function of lower and upper cutoff voltages. The post-mortem analysis of the thickness change in the cycled electrode cross-section offers corroborating evidence to support the enhancement of the cycle stability of Si@void@C electrodes via control of charge/discharge protocols to minimize the volume change of Si@void@C electrodes with a small sacrifice in their specific capacity.

FeNb 11 O 29 , pure or doped with metal transition ions, is a very promising material with advanced multi-functionalities and interesting applicative perspectives. It is isostructural with Nb 12 O 29 , one of the rare compounds in which Nb displays a local magnetic moment and shows both antiferromagnetic ordering and metallic conductivity at low temperatures. In this work we have synthesized and studied Fe 0.8 V 0.2 Nb 11 O 29 monoclinic powders. In particular we monitored the effects on structural, electronic and magnetic properties in samples produced in different atmospheres to stabilize cations with different oxidation states. We have demonstrated that the reaction atmosphere influences the phase homogeneity, the crystallite size and the amount of paramagnetic centres, with a transformation of Fe 3+ in Fe 2+ when an inert atmosphere is used, as proved by the absence, in this case, of any electron paramagnetic resonance signal. Also the Raman spectra result to be affected due to the change of coordination polyhedra. Subsequent re-oxidation of reduced powders brings to the monophasic iron niobate again containing Fe 3+ demonstrating the reversibility of redox process. This reversibility is accompanied by a complete restoring of monoclinic structure evidenced by X-ray diffraction data and by Raman measurements, which allowed also to follow in situ the spectral changes induced by laser heating.

Applications of silicon as a high-performance anode material have been impeded by its low intrinsic conductivity and huge volume expansion (>300%) during lithiation. To address these problems, nano-Si particles along with conductive coatings and engineered voids are often employed, but this results in high-cost anodes. Here, we report a scalable synthesis method that can realize high specific capacity (∼800 mAh g −1), ultrafast charge/discharge (at 8 A g −1 Si), and high initial Coulombic efficiency (∼90%) with long cycle life (1000 cycles) at the same time. To achieve 1000 cycle stability, micron-sized Si particles are subjected to high-energy ball milling to create nanostructured Si building blocks with nanochannel-shaped voids encapsulated inside a nitrogen (N)-doped carbon shell (termed as Si microreactor). The nanochannel voids inside a Si microreactor not only offer the space to accommodate the volume expansion of Si but also provide fast pathways for Li-ion diffusion into the center of the nanostructured Si core and thus ultrafast charge/discharge capability. The porous N-doped carbon shell helps to improve the conductivity while allowing fast Liion transport and confining the volume expansion within the Si microreactor. Submicron-sized Si microreactors with a limited specific surface area (35 m 2 g −1) afford sufficient electrode/electrolyte interfacial area for fast lithiation/delithiation, leading to the specific capacity ranging from ∼800 to 420 mAh g −1 under ultrafast charging conditions (8 A g −1), but not too much interfacial area for surface side reactions and thus high initial Coulombic efficiency (∼90%). Since Si microreactors with superior electrochemical properties are synthesized via an industrially scalable and eco-friendly method, they have the potential for practical applications in the future.

The increase in energy density of the next generation of battery materials to meet the new challenges of the electrical vehicles era calls for innovative and easily scalable materials with sustainable processes. An innovative Cu x O/C nanocomposite material, characterized by a highly conductive 3D-framework, with Cu x O/Cu-metal contiguous nanodomains is prepared by electrospinning. The electrode processing is made using a polyacrylic acid binder. The nanocomposite has been fully characterized and the electrochemical performance shows high specific capacity values over 450 galvanostatic cycles at 500 mAg À 1 specific current with capacity retention values over 80 %. In addition, the composite shows remarkable high rate performance and highly stable interface, which has been studied by impedance spectroscopy.

Polymer-coated Carbon Nanotube (CNT) tissues are very flexible and lightweight and have high potential as an anode material for flexible Li-ion microbatteries. The electrochemical deposition of p-sulfonated poly(allyl phenyl ether) (SPAPE) polymer electrolyte into CNT tissues has been accomplished using a cyclic voltammetry (CV) technique. When compared to a pristine CNT tissue, the capacity of SPAPE-coated CNT tissue after 10 cycles of CV is improved about 67% at 1C rate. The enhancement of electrochemical performance is obtained when the CNT tissues are coated with the SPAPE polymer electrolyte. The higher capacity of the SPAPE-coated CNT tissue is attributed to the increased surface area and the improved quality of the electrode/electrolyte interfaces between the nanotubes and the polymer electrolyte. The SPAPE-coated CNT tissue delivers a higher reversible capacity of 750 mAh g−1 (276 µAh cm−2) compared to a pristine CNT tissue, which solely provides a reversible capacity of 450 mAh g−1 (166 µAh cm−2) after 110 cycles at 1C rate. Remarkably, the SPAPE-coated CNT tissue reaches a high capacity up to 12C rate while observing that the capacity can be significantly recovered.

Manganese cobaltite (MnCo2O4) is currently under screening as a high performance supercapacitor electrode owing to its high theoretical capacitance, improved electrical conductivity and long term cyclic stability. Herein, we report synthesis of MnCo2O4 cuboidal microcrystals using hydrothermal method and compare its performance with its flakes prepared by solid combustion process. Crystal structure, surface properties, and electrochemical properties of the flakes are studied using X-ray diffraction, gas adsorption, field emission scanning electron microscopy, cyclic voltammetry, galvanostatic charge-discharge cycling, and electrochemical impedance spectroscopy. The electrochemical properties of MnCo2O4 flakes synthesized using hydrothermal synthesis are superior to that synthesized using the solid combustion process. Electrochemical properties of the cuboidal microcrystals (∼specific capacitance, CS ∼600 F g-1 @ 0.5 A g-1) are superior to those synthesized by the combustion process ...

Conversion‐enabled transition metal oxides are mostly characterized by environmental benignity, low cost, and high theoretical capacities, which make them suitable as candidate anode materials for Li‐ion batteries. To ensure high efficiency and stability, the use of novel and tailored morphologies is recommended. Among the other methods, the use of natural extracts as templates is one of the possible strategies to accomplish this task. In this work, Fe2O3 nanoparticles are synthesized by using vanillin as a soft templating agent, and fully characterized on a morphological, structural and electrochemical level. Poly(acrylic acid) binder and ethanol for electrode preparation ensure a fully environmentally benign process from synthesis to electrode testing. The cells deliver capacity values up to 700 mAh g−1 under prolonged galvanostatic cycling at 500 mA g−1, as well as excellent rate capability and high efficiency.

We report the electrodeposition of polymer electrolyte (PMMA-PEG) in porous lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O 4) cathode layer by cyclic voltammetry. The cathode-electrolyte interface of the polymer-coated LNMO electrode has been characterized by scanning electron microscopy and electrochemical techniques. Electrochemical measurements consisting of galvanostatic cycling tests and electrochemical impedance spectroscopy revealed a significant improvement of the capacity values and the increase of the operating voltage. These effects are attributed to the total filling of pores by the electrodeposited polymer that contributes to improve the reversible insertion of Li +. A complete all-solid-state microbattery consisting of electropolymerized LNMO as the cathode, a thin polymer layer as the electrolyte, and TiO 2 nanotubes as the anode has been successfully fabricated and tested.

Silicon/graphite (Si/Gr) nanocomposites with controlled void spaces and encapsulated by a carbon shell (Si/Gr@void@C) are synthesized by utilizing high-energy ball milling to reduce micron-sized particles to nanoscale, followed by carbonization of polydopamine (PODA) to form a carbon shell, and finally partial etching of the nanostructured Si core by NaOH solution at elevated temperatures. In particular, the effects of ball milling time and NaOH etching temperature on the electrochemical properties of Si/Gr@void@C are investigated. Increasing the ball milling time results in the improved specific capacity of Si-based anodes. Carbon coating further enhances the specific capacity and capacity retention over charge/discharge cycles. The best cycle stability is achieved after partial etching of the Si core inside Si/Gr@void@C particles at either 70 or 80 °C, leading to little or no capacity decay over 130 cycles. However, it is found that both carbon coating and NaOH etching processes cause some surface oxidation of the nanostructured Si particles derived from high-energy ball milling. The surface oxidation of the nanostructured Si results in decreases in specific capacity and should be minimized in future studies. The mechanistic understanding developed in this study paves the way to further improve the electrochemical performance of Si/Gr@void@C nanocomposites in future.

Conversion‐enabled transition metal oxides are mostly characterized by environmental benignity, low cost, and high theoretical capacities, which make them suitable as candidate anode materials for Li‐ion batteries. To ensure high efficiency and stability, the use of novel and tailored morphologies is recommended. Among the other methods, the use of natural extracts as templates is one of the possible strategies to accomplish this task. In this work, Fe2O3 nanoparticles are synthesized by using vanillin as a soft templating agent, and fully characterized on a morphological, structural and electrochemical level. Poly(acrylic acid) binder and ethanol for electrode preparation ensure a fully environmentally benign process from synthesis to electrode testing. The cells deliver capacity values up to 700 mAh g−1 under prolonged galvanostatic cycling at 500 mA g−1, as well as excellent rate capability and high efficiency.

Lithium dendrite growth dynamics on Cu surface is first visualized through a versatile and facile experimental cell by in operando transmission X-ray microscopy (TXM). Galvanostatic plating and stripping cycle(s) are applied on each cell. Upon plating/stripping process at ~ 1 mA cm-2, mossy lithium was clearly found growing and shrinking on the Cu surface as the applying time increases. It is interesting to note that the aspect ratio (height/width) of deposited lithium has increased with charge passed during plating, indicating a faster growing from the base. In addition, the dendritic or mossy lithium have been also observed when various high current densities (25 mA cm-2, 12.5 mA cm-2 and 6.3 mA cm-2) were applied in different cycle, showing a severe dendritic lithium formation that could be induced by inhomogeneous current distribution. The clear structure of dead lithium is found after the cycling, which also shows a lower efficiency and higher hazard when applying a higher current density. This work explores
TXM as a useful tool for in operando dynamic visualization and quantitative measurement of lithium dendrite which is difficult to achieve with ex situ measurements and other microscopy techniques. The understanding of growth mechanism from TXM can be beneficial for the development of safe lithium ion and lithium metal batteries.

The growth of silicon nanoparticles on a graphene surface without forming the unwanted silicon carbide (SiC) phase has been challenging. Herein, the critical issues surrounding silicon anode materials for lithium-ion batteries, such as electrode pulverization, unstable solid electrolyte interphase and low electrical conductivity, have been addressed by growing silicon nanoparticles smaller than 10 nm, covalently bonded to a reduced graphene oxide (rGO) surface. The successful growth of SiC-free silicon nanoparticles covalently attached to the rGO surface was confirmed by using various spectroscopic and microscopic analyses. The rGO–Si delivered an initial discharge capacity of 1338.1 mA h g À1 with capacity retention of 87.1% after the 100th cycle at a current rate of 2100 mA g À1 , and exhibited good rate capability. Such enhanced electrochemical performance is attributed to the synergistic effects of combining ultra-small silicon nanoparticles and rGO nanosheets. Here, rGO provides a continuous electron conducting network, whereas, ultra-small silicon particles reduce ionic diffusion path length and accommodate higher stress during volume expansion upon lithiation.

Interactive binders are of current interest to the lithium-ion battery community because they are beneficial
for alloy-based anodes. They can accommodate the extra stress generated during the reaction with lithium
well and alleviate the pulverization problem associated with the alloying–dealloying process. One of the
best examples of an interactive binder is sodium alginate, which has recently being used in silicon-based
anodes. The silicon–alginate binder combination has exhibited excellent electrochemical reactivity and
stability. Herein, we have utilized the interactive properties of the alginate binder along with the hollow
nanostructural features of a-Fe2O3 nanotubes in order to achieve an excellent conversion-based anode for
lithium-ion batteries. In this regard, a-Fe2O3 is synthesized using a simple hydrothermal method and the
hollow nanostructured a-Fe2O3 nanotubes have shown a stable high capacities of about 800 mAh g21 at
503 mA g21 for 50 cycles with alginate binder. Even at a high current rate of 1007 mA g21 (y1C), high
capacity of 732 mAh g21 and 600 mAh g21 has been achieved after 50 and 100 cycles respectively. The
same electrode assembly has shown an excellent high rate capability and delivered a capacity of 400 mAh
g21 even at a very high current density of 10 A g 21. In this report we propose that weak hydrogen
bonding between the surface hydroxyl groups on the metal oxide (Fe2O3) and the carboxylic functional
groups on the alginate binder is responsible for the enhanced battery performance at very high current
rates.

All-solid-state batteries were fabricated by assembling a layer of self-organized TiO2 nanotubes grown on as anode, a thin-film of polymer as an electrolyte and separator, and a layer of composite LiFePO4 as a cathode. The synthesis of self-organized TiO2 NTs from Ti-6Al-4V alloy was carried out via one-step electrochemical anodization in a fluoride ethylene glycol containing electrolytes. The electrodeposition of the polymer electrolyte onto anatase TiO2 NTs was performed by cyclic voltammetry. The anodized Ti-6Al-4V alloys were characterized by scanning electron microscopy and X-ray diffraction. The electrochemical properties of the anodized Ti-6Al-4V alloys were investigated by cyclic voltammetry and chronopotentiometry techniques. The full-cell shows a high first-cycle Coulombic efficiency of 96.8% with a capacity retention of 97.4% after 50 cycles and delivers a stable discharge capacity of 63 μAh cm −2 μm −1 (119 mAh g −1) at a kinetic rate of C/10.