Negative Electrode Material For Lithium-ion Batteries Research Articles

Boosting Li-ion storage kinetics via constructing layered TiO2 anode

Due to the typical intercalation-deintercalation mechanism, TiO2 holds great promise as a sustainable anode for next-generation lithium-ion batteries (LIBs). However, commercial TiO2 (C–TiO2) is granular and shows slow ionic conductivity, which greatly hinders its development due to sluggish kinetics, leading to low reversible capacity and inferior rate capability. In this study, a two-dimensional layered TiO2 (L-TiO2) anode is prepared via a one-step calcination process, which can effectively shorten the lithium ions diffusion path and improve its lithium ions conductivity. We elucidated the enhanced electrochemical performance of L-TiO2 as an anode in LIBs through pseudocapacitive acceleration of lithium ions intercalation and deintercalation using various characterization techniques, including different scan rate cyclic voltammetry tests, in situ electrochemical impedance spectroscopy, in situ Raman spectroscopy, and in situ X-ray diffraction. In comparison to C–TiO2 material, L-TiO2 material showcases remarkable electrochemical performance, achieving a capacity of 166 mAh/g after 100 cycles at 0.1 C. Additionally, the lithium-ion diffusion coefficient calculated for the L-TiO2 is two orders of magnitude greater, underscoring its potential as a negative electrode material for LIBs.

Corn straw-derived porous carbon as negative-electrode materials for lithium-ion batteries

Corn straw-derived porous carbon as negative-electrode materials for lithium-ion batteries

Electrochemical Synthesis of Multidimensional Nanostructured Silicon as a Negative Electrode Material for Lithium-Ion Battery.

Silicon (Si) is a promising negative electrode material for lithium-ion batteries (LIBs), but the poor cycling stability hinders their practical application. Developing favorable Si nanomaterials is expected to improve their cyclability. Herein, a controllable and facile electrolysis route to prepare Si nanotubes (SNTs), Si nanowires (SNWs), and Si nanoparticles (SNPs) from halloysite clay (Al2(OH)4Si2O5·nH2O) is developed. It is found that HCl-etching temperature and electrolysis potential play key roles in controlling the morphologies of Si. After being HCl-etched at 80 or 90 °C, halloysite clay can be reduced into Si nanotubes at a suitable potential of -1.45 V or Si nanowires at a wide potential from -1.40 to -1.60 V, respectively, while Si nanoparticles can be only obtained at a more negative potential of -1.60 V without HCl-etching. The different morphologies of Si are associated with the change of reduction kinetics after HCl-etching. Besides, when serving as negative electrode materials for LIBs, Si nanotubes exhibit better Li storage performance than Si nanoparticles and Si nanowires, showing a capacity of 3044 mAh g-1 at 0.20 A g-1 and 1033 mAh g-1 after 1000 cycles at 1 A g-1. This work provides a controllable approach for the synthesis of Si nanomaterials for LIBs.

Mechanisms and Product Options of Magnesiothermic Reduction of Silica to Silicon for Lithium-Ion Battery Applications

Lithium-ion batteries (LIBs) have been one of the most predominant rechargeable power sources due to their high energy/power density and long cycle life. As one of the most promising candidates for the new generation negative electrode materials in LIBs, silicon has the advantages of high specific capacity, a lithiation potential range close to that of lithium deposition, and rich abundance in the earth’s crust. However, the commercial use of silicon in LIBs is still limited by the short cycle life and poor rate performance due to the severe volume change during Li++ insertion/extraction, as well as the unsatisfactory conduction of electron and Li+ through silicon matrix. Therefore, many efforts have been made to control and stabilize the structures of silicon. Magnesiothermic reduction has been extensively demonstrated as a promising process for making porous silicon with micro- or nanosized structures for better electrochemical performance in LIBs. This article provides a brief but critical overview of magnesiothermic reduction under various conditions in several aspects, including the thermodynamics and mechanism of the reaction, the influences of the precursor and reaction conditions on the dynamics of the reduction, and the interface control and its effect on the morphology as well as the final performance of the silicon. These outcomes will bring about a clearer vision and better understanding on the production of silicon by magnesiothermic reduction for LIBs application.

Stable Cycle Performance of a Phosphorus Negative Electrode in Lithium-Ion Batteries Derived from Ionic Liquid Electrolytes.

Although high-capacity negative electrode materials are seen as a propitious strategy for improving the performance of lithium-ion batteries (LIBs), their advancement is curbed by issues such as pulverization during the charge/discharge process and the formation of an unstable solid electrolyte interphase (SEI). In particular, electrolytes play a vital role in determining the properties of an SEI layer. Thus, in this study, we investigate the performance of a red phosphorus/acetylene black composite (P/AB) prepared by high-energy ball milling as a negative electrode material for LIBs using organic and ionic liquid (IL) electrolytes. Galvanostatic tests performed on half cells demonstrate high discharge capacities in the 1386-1700 mAh (g-P/AB)-1 range along with high Coulombic efficiencies of 85.3-88.2% in the first cycle, irrespective of the electrolyte used. Upon cycling, the Li[FSA]-[C2C1im][FSA] (FSA- = bis(fluorosulfonyl)amide and C2C1im+ = 1-ethyl-3-methylimidazolium) IL electrolyte (2:8 in mol) demonstrates a high capacity retention of 78.8% after 350 cycles, whereas significant capacity fading is observed in the Li[PF6] and Li[FSA] organic electrolytes. Electrochemical impedance spectroscopy conducted with cycling revealed lower interfacial resistance in the IL electrolyte than in the organic electrolytes. Scanning electron microscopy and X-ray photoelectron spectroscopy after cycling in different electrolytes evinced that the IL electrolyte facilitates the formation of a robust SEI layer comprising multiple layers of sulfur species resulting from FSA- decomposition. A P/AB|LiFePO4 full cell using the IL electrolyte showed superior capacity retention than organic electrolytes and a high energy density under ambient conditions. This work not only illuminates the improved performance of a phosphorous-based negative electrode alongside ionic liquid electrolytes but also displays a viable strategy for the development of high-performance LIBs, especially for large-scale applications.

Graphene induced growth of Sb2WO6 nanosheets for high-performance pseudocapacitive lithium-ion storage

Abstract Transition metal oxides with the Aurivillius structure have been studied as electrode materials in lithium-ion batteries (LIBs) owing to their high capacity and proper redox voltage. With the opened Aurivillius structure, the antimony tungstate (Sb2WO6, SWO) constituted of {Sb2O2}2n+ and {WO4}2n− is rarely used as negative electrode material for lithium-ion batteries. Herein, the SWO nanosheets/reduced graphene oxide (rGO) hybrid clusters were synthesized, and their electrochemical performances, kinetics and lithium storage mechanism were systematically studied as negative electrode materials for LIBs. Results show that the graphene oxide (GO) not only restricts the growth of layered-structure SWO, but also induces SWO growth along (002) lattice plane and changes SWO particles to SWO nanosheets. The strong interaction between SWO nanosheets and rGO greatly improve conductivity and structure stability of SWO nanosheets/rGO hybrid clusters, which also can efficiently alleviate agglomeration and volume change of SWO nanosheets during cycling. Meanwhile, the dominating pseudocapacitive contribution (78.2% at 0.8 mV s−1) effectively enhanced the electrochemical performance. As an anode material for LIBs, the SWO nanosheets/rGO hybrids deliver a high specific capacity of 1141 mAh g−1 at a current density of 0.2 A g−1, and their specific discharge capacity is 595 mAh g−1 after 130 cycles at 0.2 A g−1. This work demonstrates that the SWO nanosheets/rGO hybrid clusters are a promising negative electrode material for high-energy-density LIBs.

Atomic Pt Promoted N-Doped Carbon as Novel Negative Electrode for Li-Ion Batteries.

In this work, platinum single-atom enhanced mushroom-based carbon (Pt1/MC) materials have been facilely synthesized and served as novel electrode materials in lithium-ion batteries (LIBs). The as-synthesized Pt1/MC active material shows a uniform dispersion of isolated Pt atoms on an MC support with high specific surface area and large total pore volume. As a negative electrode material for LIBs, the Pt1/MC exhibits excellent electrochemical properties, which retains a capacity of 846 mA h g-1 after 800 cycles at 2 A g-1 and 349 mA h g-1 (near to the theoretical capacity of graphite) after 6000 cycles at a high current density of 5 A g-1. The remarkable high capacity and excellent cycling stability can be attributed to their porous nanostructures and atomic-Pt-enhanced lithium-ion storage. Atomic Pt can compound with Li+ ions to form a platinum-lithium alloy during the discharge and charge process. Density functional theory (DFT) calculations are performed to verify that the PtLi5 alloy is the most stable intermedium on the MC substrate, which further enhances the lithiation and delithiation kinetics. This novel perspective is helpful to explore next-generation negative electrode materials with high capacities and good stabilities for LIBs.

Highly conductive CrNb11O29 nanorods for use in high-energy, safe, fast-charging and stable lithium-ion batteries

Ti2Nb2xO4+5x compounds are very popular negative-electrode materials for lithium-ion batteries due to their high specific capacities, safe operating potentials and high cycling stability. Nevertheless, their poor electronic conductivities and insufficient Li+ diffusion coefficients limit the rate capabilities. Herein, we explore highly conductive CrNb11O29 with a high theoretical capacity (401 mAh g−1) and an open Wadsley–Roth shear structure as a new intercalating negative-electrode material having the same advantages of Ti2Nb2xO4+5x but a high rate capability. CrNb11O29 nanorods (CrNb11O29-R) with lengths of 500–1000 nm and very small diameters of 30–50 nm are prepared based on a novel hydrothermal method. Due to the free electrons in Cr-3d orbitals and the large ionic radius of Cr3+, CrNb11O29 exhibits a high electronic conductivity and large Li+ diffusion coefficients, respectively. In-situ X-ray diffraction analyses confirm its high structural stability. These conductivity, structural and architectural advantages in CrNb11O29-R lead to its significant pseudocapacitive contribution (82.0% at 1.1 mV s−1), prominent rate capability (high reversible capacities of 343 mAh g−1 at 0.1C and 228 mAh g−1 at 10C), and outstanding cycling stability (only 8.9% capacity loss at 10C over 400 cycles).

In-Situ Synthesis of Sn/SnO2@C Composites for Lithium and Sodium-Ion Batteries

Tin oxide (SnO2) is considered as a promising material for both Li- and Na-ion batteries due to its high theoretical capacities (1494 mAh/g with Li and 1378 mAh/g with Na; 2~3 times higher than common carbon-based anode)1-3. However, the initial irreversible capacity loss induced by inactive Li2O/Na2O formation and volume change (260% with Li and 420% with Na) during charge/discharge process need to be addressed in order to improve cycling performance4. In addition, the poor electronic conductivity of above mentioned alkali metal oxides and gradual aggregation of Sn particles in the electrode structure during operation lead to poor rate capability and rapid capacity fading. Many studies have strived to address these issues and result in the development of diverse types of SnO2-based nanocomposites with carbonaceous materials including reduced graphene oxides5-7, carbon nanofibers8,9, carbon nanotubes10,11, and disordered carbons12,13 to enhance initial coulombic efficiency and electronic conductivity in the electrode structure as well as to prohibit Sn particle aggregation by introducing physical barriers between active materials. However, the cycling performance and initial irreversible capacity loss of the currently reported composites still remain insufficient to be adopted in practical cells. In this work, carbon-coated porous Sn/SnO2 composite (Sn/SnO2@C) is synthesized via inorganic CO2 reduction route with magnesium stannide (Mg2Sn) for Li- and Na-ion batteries. High purity Mg2Sn powder is prepared by solid-state reaction and then thermally treated under CO2 flow environment. During the second heat treatment, gaseous CO2 molecules becomes reduced down to elemental C via interaction with Mg which is known to be highly reductive in nature (Mg2Sn + CO2 à 2MgO + Sn + C, ΔG = -690 kJ/mol). The resultant Sn is partially oxidized to form SnO2 which eventually results in Sn/SnO2@C composite. Electrodes with this composition and structure exhibit enhanced initial coulombic efficiency and stable cycling performance. It appears that a nanocomposite matrix in which active materials are distributed without aggregation in intimate contact with C is essential for realizing SnO2-based anodes for Li- and Na-ion batteries with long cycle life. 1 Lee, J.-I. et al. Multifunctional SnO2/3D graphene hybrid materials for sodium-ion and lithium-ion batteries with excellent rate capability and long cycle life. Nano Research, doi:10.1007/s12274-017-1756-3 (2017). 2 Kim, Y., Yoon, Y. & Shin, D. Fabrication of Sn/SnO2 composite powder for anode of lithium ion battery by aerosol flame deposition. Journal of Analytical and Applied Pyrolysis 85, 557-560, doi:https://doi.org/10.1016/j.jaap.2008.06.005 (2009). 3 Lee, Y. et al. Hollow Sn–SnO2 Nanocrystal/Graphite Composites and Their Lithium Storage Properties. ACS Applied Materials & Interfaces 4, 3459-3464, doi:10.1021/am3005237 (2012). 4 Sivashanmugam, A. et al. Electrochemical behavior of Sn/SnO2 mixtures for use as anode in lithium rechargeable batteries. Journal of Power Sources 144, 197-203, doi:https://doi.org/10.1016/j.jpowsour.2004.12.047 (2005). 5 Hu, X., Zeng, G., Chen, J., Lu, C. & Wen, Z. 3D graphene network encapsulating SnO2 hollow spheres as a high-performance anode material for lithium-ion batteries. Journal of Materials Chemistry A 5, 4535-4542, doi:10.1039/C6TA10301D (2017). 6 Fan, L. et al. Controlled SnO2 Crystallinity Effectively Dominating Sodium Storage Performance. Advanced Energy Materials 6, 1502057-n/a, doi:10.1002/aenm.201502057 (2016). 7 Tian, R. et al. The effect of annealing on a 3D SnO2/graphene foam as an advanced lithium-ion battery anode. Scientific Reports 6, 19195, doi:10.1038/srep19195 https://www.nature.com/articles/srep19195#supplementary-information (2016). 8 Wang, M., Li, S., Zhang, Y. & Huang, J. Hierarchical SnO2/Carbon Nanofibrous Composite Derived from Cellulose Substance as Anode Material for Lithium-Ion Batteries. Chemistry – A European Journal 21, 16195-16202, doi:10.1002/chem.201502833 (2015). 9 Liu, Y. et al. Enhanced electrochemical performance of hybrid SnO2@MOx (M = Ni, Co, Mn) core-shell nanostructures grown on flexible carbon fibers as the supercapacitor electrode materials. Journal of Materials Chemistry A 3, 3676-3682, doi:10.1039/C4TA06339B (2015). 10 Cui, J. et al. Enhanced conversion reaction kinetics in low crystallinity SnO2/CNT anodes for Na-ion batteries. Journal of Materials Chemistry A 4, 10964-10973, doi:10.1039/C6TA03541H (2016). 11 Chen, S. et al. Branched CNT@SnO2 nanorods@carbon hierarchical heterostructures for lithium ion batteries with high reversibility and rate capability. Journal of Materials Chemistry A 2, 15582-15589, doi:10.1039/C4TA03218G (2014). 12 Fan, J. et al. Ordered, Nanostructured Tin-Based Oxides/Carbon Composite as the Negative-Electrode Material for Lithium-Ion Batteries. Advanced Materials 16, 1432-1436, doi:10.1002/adma.200400106 (2004). 13 Pol, V. G., Wen, J., Miller, D. J. & Thackeray, M. M. Sonochemical Deposition of Sn, SnO2 and Sb on Spherical Hard Carbon Electrodes for Li-Ion Batteries. Journal of The Electrochemical Society 161, A777-A782, doi:10.1149/2.064405jes (2014).

Sb-Based Transition Metal Oxohalides As Negative Electrode Materials for Lithium Ion Batteries

An electrochemical and structural investigation of two transition metal oxohalides has been undertaken. As negative electrodes for Li-ion batteries, these materials exhibit a combination of both conversion and alloying reactions within the same cell, giving rise to interesting electrochemical performances. Alloying-type reactions, typically involving Si, Sn or - as in this case - Sb, generally occur at low potentials vs. Li+/Li and show relatively good reaction kinetics. The main concern regarding alloying reactions, however, is the expansion/contraction exerted by repeated insertion of Li+, which leads to poor cycleability over time. Storage of Li in the family of conversion materials is based on the conversion of metal oxides into metallic nano-clusters and Li2O.1 This generally occurs at higher potentials and with larger voltage polarization between the charge and discharge processes. Here, these two types of reactions are exemplified using Ni3Sb4O6F6 2 and Mn2Sb3O6Cl3 with the intent of finding a compromise between the alloying and conversion mechanisms. The inclusion of a halide allows for a more careful tuning of the crystal structure. In this respect, the relatively open structures are believed to at least partly affect the insertion of Li, and thereby the efficiency of the conversion process in the early stages of lithiation. The choice of the transition metal (i.e. Mn or Ni) and its specific redox potential vs. Li+/Li effectively determines the order in which the (transition metal oxide-conversion) ↔ (antimony conversion-alloying) reaction sequence occurs, with possibly crucial consequences. Both compounds are shown to react reversibly with Li, with a good cycleability, in complex systems where multiple reactions occur sequentially and/or simultaneously via the in-situ formation of a nano-composite material. Operando XRD complemented with ex-situ XRD, XANES, TEM and an extensive electrochemical analysis have been used to illuminate the mechanisms involved. 1. Poizot, P.; Laruelle, S.; Grugeon, S.; Dupont, L.; Tarascon, J. M., Nano-sized transition-metal oxides as negative-electrode materials for lithium-ion batteries. Nature 2000, 407, 496-499. 2. Hu, S.; Johnsson, M.; Lemmens, P.; Schmid, D.; Menzel, D.; Tapp, J.; Möller, A., Acentric Pseudo-Kagome Structures: The Solid Solution (Co1–xNix)3Sb4O6F6. Chemistry of Materials 2014, 26 (12), 3631-3636. 3. Zimmermann, I.; Johnsson, M., A Synthetic Route toward Layered Materials: Introducing Stereochemically Active Lone-Pairs into Transition Metal Oxohalides. Crystal Growth & Design 2014, 14 (10), 5252-5259.

Remarkable performance improvement of inexpensive ball-milled Si nanoparticles by carbon-coating for Li-ion batteries

Si nanoparticles prepared by ball-milling (BM-Si) are expected as practical negative-electrode materials for lithium-ion batteries, but their performance is much lower than those of more expensive Si nanomaterials, such as chemical-vapor-deposition derived Si nanoparticles (CVD-Si) having a tight network structure. It is found that carbon-coating of aggregations of BM-Si forms a quasi-network structure, thereby making the performance comparable to that of CVD-Si under capacity restriction (to 1500 mAh g−1). In this case, the structural transition of BM-Si during charge/discharge cycling is characterized by the formation of a specific ‘wrinkled structure’, which is very similar to that formed in CVD-Si.

Batteries: Bigger and better

Micrometre-sized silicon particles are attractive negative-electrode materials for lithium-ion batteries but are prone to mechanical failure during electrochemical cycling. Now, graphene cages grown conformally around the micro-silicon particles are shown to improve their cycling stability.

New Metal Phosphide with Topotatic Reaction As an Anode Material for Lithium Ion Rechargeable Battery

The current level of performances of Lithium Ion Batteries (LIBs) is not enough to meet commercial demands for new applications(xEV, ESS), in particular, with respective to energy density. Graphite and hard carbons are commonly used as a negative electrode material for LIBs, but higher-capacity alternatives are being consistently sought due to their limited capacity as an anode material of next generation LIBs for large-scale power applications. Recently, various Si, and Sn based compound including transition metal oxide, multiphase alloy, and intermetallic compounds have been extensively studied as alternatives to the existing carbon based anode material. These materials show much higher capacities than those of carbonaceous material. However, they are suffering from huge lattice volume change (4.4Li+Si ® Li4.4Si, ΔV>300%) through conversion reaction mechanism during Li insertion, which results in poor cycle life of LIBs. In this respect, metal phosphides have been alternatively suggested as a promising anode material for their reversibility, and large amount of lithium uptake at relatively low potential. It is not clarified yet until now, but the electrochemical reaction in metal phosphides with lithium might be classified into two reaction mechanisms, depending on electronegativity difference between metal and phosphorous atoms. Obviously, the large difference in electronegativity between constituting elements inevitably brings about decomposition of host composition (structure) with lithium intercalation, which can be readily understood by considering the Gibbs formation free energy. Even if being composed of elements with the very small difference in electronegativity, however, the reaction mechanisms are different with chemical stoichiometry of metal phosphides (MPx). In case of SnPx (Electronegativity : Sn=1.96, P=2.19) intermetallic compounds, the SnP0.75 equilibrium phase shows typical conversion reaction mechanism, on the other hand, SnP0.94metastable phase has been observed to be on intercalation reaction mechanism during lithiation process [1,2]. In this work, we have investigated the reaction mechanism of MoPx(Electronegativity : Mo=2.16, P=2.19) with various stoichiometry, relating with electrochemical properties. We finally propose newly designed metal phosphide with ternary composition showing topotatic reation.

Effects of the Thickness of Silicon Thin Films on the Charge and Discharge Performance As Negative Electrodes for Lithium-Ion Batteries

Introduction Silicon is an attractive high-capacity negative-electrode material for lithium-ion batteries because it can accommodate 3.75 lithium atoms per 1 silicon atom at room temperature, which corresponds to a theoretical capacity of about 4200 mAh/g [1]. Silicon is also a light, abundant and cheap material. It represents the second most abundant element in the earth’s crust after oxygen. However, silicon have a problem; large volume expansion occurs when it reacts with lithium to form alloys. This leads to the degradation of the electrode with a loss of electrical contacts among silicon, conductive additives and current collector of copper foil, and as a result electrically isolated silicon particles should arise. This facts explain the low Coulombic efficiency and the decrease in reversible capacities for silicon electrodes. In addition, electrolyte solution is reductively decomposed at negative potentials where silicon is alloyed with lithium, which is followed by the formation of surface films on the surface of the silicon. Thus, the charge/discharge performance is influenced profoundly by the volume changes of silicon and the formation of surface films. The impacts of the former issue can be alleviated by use of silicon with short diffusion paths for lithium. Hence, in this study, we investigated the influence of the thickness of silicon on the charge/discharge performance using silicon thin-film electrodes with three different thicknesses (50, 100, 200 nm). Experimental We used silicon thin-film electrodes deposited on Cu substrates by an electron beam evaporation method. The surface morphology was investigated by atomic force microscopy (AFM). AFM images were obtained in conventional contact-mode with pyramidal silicon nitride tips (spring constant; 0.02 N m-1, Olympus). Silicon thin-film electrodes were used as working electrodes. Electrochemical cells were assembled by stacking the silicon thin film electrode, a polymer separator soaked with electrolyte solution, and a lithium metal (Honjo Metal) for counter electrodes. The electrolytes used in this study were 1 mol dm-3 LiPF6 dissolved in a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) with an EC/EMC volume ratio of 1:1, and a mixture of fluoroethylene carbonate (FEC) and EMC with an FEC/EMC ratio of 1:1. The electrochemical cells were cycled between 0.02 V and 1.5 V at C/2 rate. Results and Discussion XRD patterns (not shown) of three kinds of silicon thin-films indicate no peak identified as silicon. These results suggest that the silicon thin film should be amorphous.Figure 1 shows an AFM image (10 mm×10 mm) of the surface of as-deposited silicon thin-film. The roughness of the film was evaluated to be 2.5 nm, whereas an obvious bump is seen as indicated by white color.Figure 2 shows charge and discharge curves of a silicon thin-film electrode. The thickness of silicon thin film is 100 nm. In the 1st cycle, a large irreversible capacity due to the formation of surface films was observed. In subsequent cycle, charge (alloying)/discharge (dealloying) reactions proceeded more reversibly.Figure 3 shows cycleability of silicon thin-film electrodes. The discharge capacities for silicon thin-film electrodes with a thickness of 100 nm decreased only by 15 % after 50 cycles. This value is much smaller than those obtained for 50-(34 %) and 200-(32 %) nm-thick. These results clearly indicate that the high cycleability is achieved with use of silicon with a thickness of about 100 nm.We will report the changes in the surface morphology of silicon thin-film electrodes studied by in situ AFM in our poster presentation.

Layered titanate nanostructures and their derivatives as negative electrode materials for lithium-ion batteries

Ti-based materials have been intensively investigated and considered as good potential negative electrode materials for lithium-ion batteries (LIBs) due to their high safety, superior rate capability and excellent cyclic stability. This feature article summarizes the recent progress of a new class of layered titanate (H2TinO2n+1·H2O) nanostructures and their derivatives, including TiO2 polymorphs, novel titanate nanostructures of Zn2Ti3O8, Li2MTi3O8 (M = Co, Zn, Mg) and Li4Ti5O12, as high performance negative electrode materials for LIBs. The effects of the composition, crystal structure and morphology on lithium-ion intercalation properties are highlighted and analyzed.

Cobalt Oxalate Nanoribbons as Negative-Electrode Material for Lithium-Ion Batteries

Orthorhombic cobalt oxalate dihydrate has been prepared in the form of nanoribbons by a reverse micelles method. The crystallographic structure of the resulting solid differs from the monoclinic massive product. A careful dehydration of the nanocrystals leads to anhydrous cobalt oxalate in which the nanoribbon-shaped particles are preserved and Co2+ ions are located in a centrosymmetric environment. CoC2O4 is used for the first time as high-capacity lithium storage materials with improved rate performance. The anhydrous solids react with lithium, leading to metallic cobalt and lithium oxalate, as shown by XAS and FTIR measurements. The new electrode material displays reversible capacities close to 900 mA·h·g−1 between 0 and 2 V versus lithium by a novel reaction mechanism which involves cobalt reduction−reoxidation.

Molybdenum Oxides as Negative-Electrode Materials for Lithium-ion Batteries

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Nanostructured Molybdenum Oxides as Negative-Electrode Materials for Lithium-Ion Batteries

not Available.

Crystalline MoO3 Nanoparticles as Negative-electrode Materials for Lithium-ion Batteries

not Available.

Electrochemical Insertion of Lithium into Graphite–Zinc Composites

Metal-based composites are currently under investigation as possible negative-electrode materials in lithium-ion batteries. We present here a new composite material composed of zinc particles deposited mainly onto graphite surfaces. This Zn/graphite composite was prepared by reduction of zinc chloride ZnCl2 by a KC8 graphite intercalation compound in tetrahydrofuran. Electrochemical insertion of lithium occurs both in graphite and in zinc. A stable specific charge of 355 mAh g−1 is obtained starting from the third charge/discharge cycle. As in Sb/graphite composites prepared by the same technique, the stabilizing role of graphite against metal fragmentation and pulverization is demonstrated.