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The properties of lithium ion battery largely depend on the structure of active materials. In the present work, CoFe _2 O _4 nanowire arrays /Cu foam three-dimensional integrated electrode (denoted as CFO/Cu-foam NWAs) was firstly designed and synthesized via a simple hydrothermal method follow annealing as a binder-free anode for lithium ion battery. The CoFe _2 O _4 nanowires with diameter of 50–100 nm are uniformly anchored on the porous conductive substrate. Lithium ion battery based on the CFO/Cu-foam NWAs integrated electrode exhibits a high initial capacity of 882.7 mAh · g ^−1 and excellent cyclic stability of 832.1 mAh · g ^−1 after 100 cycles at 1.0 A · g ^−1 which is much better than traditional coated electrode of CoFe _2 O _4 nanowire (defined as CFO NWAs) and CoFe _2 O _4 nanowire/Cu foil integrated electrode (named CFO/Cu-foil NWAs). The improved electrochemical performance might be attributed to superior conductivity and porous skeleton structure which not only reduce contact resistance and polarization, but also relieve volume alteration during the lithiation/delithiation process. These advantages make the CoFe _2 O _4 /Cu foam integrated electrode a promising anode for Li-ion batteries.

Abstract A carbon nanotube sheet having homogeneously distributed BaTiO 3 is applied to the Li-S cell system as a pseudo-current collector between the cathode and separator. This interlayer serves as a site distributor, where polysulfide eluted from the cathode continuously reacts, and it is expected to play a role as a more effective current collector by mixing the ferroelectric material. A cell utilizing a ferroelectricity embedded interlayer exhibits a higher capacity (908 mAh g−1) at 0.2C than that of carbon alone (740 mAh g−1) at 200th cycle. This result corresponds to a capacity retention ratio enhancement from 67.5% to 75.6%. Furthermore, it is confirmed that the retention of the coulombic efficiency is effectively maintained in long cycles at 0.5C (94.5%–99.6%). This is not only because the modified interlayer functions as an effective current collector owing to the high affinity of the ferroelectric material to polysulfide, but also because ferroelectricity in the interlayer acts as a polysulfide anchor. The evenly distributed polarization leads to a uniform deposition of sulfur, which results in the prevention of inactive sulfur agglomeration and dissolution of polysulfide. Thus, the utilization of active material can be improved with stabilized reaction. Graphical abstract Image 1 Highlights • Nano-BaTiO 3 embedded MWCNT interlayer is fabricated by vacuum filtration method. • BaTiO 3 interlayer cell performs higher specific capacity and coulombic efficiency. • BaTiO 3 interlayer cell enhances rate capability. • BaTiO 3 interlayer induces homogeneous S distribution with strong affinity. • BaTiO 3 interlayer acts as an efficient pseudo-current collector. [ABSTRACT FROM AUTHOR]

Abstract Fe 3 O 4 @C composite was designed and synthesized by a facile one-step solvothermal route as an anode material for Li-ion batteries (LIBs). The carbon shell can effectively prevent the aggregation and buffer the volume expansion during charge/discharge process. The electrochemical performance displays that the Fe 3 O 4 @C composite exhibits high reversible capacity and good cycling performance. In particular, it displays excellent cycling stability at 2 C rate (640.5/642.2 mA h g−1 after 1000 cycles). The results indicate a simple and useful route to prepare Fe 3 O 4 @C composite as a promising LIBs anode material. Graphical abstract Fe 3 O 4 @C composite with high reversible capacity and good cycling performance has been synthesized by a facile one-step solvothermal route as an anode material for Li-ion batteries (LIBs). fx1 Highlights • Fe 3 O 4 @C composite has been synthesized by a facile one-step solvothermal route. • Fe 3 O 4 @C composite has been studied as an anode material for LIBs. • Fe 3 O 4 @C composite displays high reversible capacity and good cycling performance. [ABSTRACT FROM AUTHOR]

Abstract This work explores the compound Li 1+z/3 Ni 1/2-z/2 Ti 1/2+z/6 O 2 (z = 0, 0.1, 0.2, 0.3, 0.4, 0.5) and compares the electrochemical performance difference with z to the proposed percolation network. X-ray diffraction combined with Rietveld refinements show that rock-salt structure is obtained by the simple sol-gel process, and the lattice parameters are increased with the increasing level of Li-excess. Micromorphology observation reveals that particles are irregular and the size is distributed within 100 nm. In addition, a detailed reaction mechanism is examined by X-ray photoelectron spectroscopy and cyclic voltammetry, which exhibits the evolution of Ni, Ti and O in the initial charge-discharge process and confirms that they all make contributions to capacities. Electrochemical performance test shows that the discharge capacities increase with the amount of Li and Li 1.17 Ni 0.25 Ti 0.58 O 2 delivers the discharge capacities up to 223.9 mAh g−1. At the current density of 400 mA g−1, it still provides a large capacity of 120 mAh g−1. Furthermore, Li 1.17 Ni 0.25 Ti 0.58 O 2 has the highest lithium ion diffusion coefficient among all samples. Graphical abstract Image 1 Highlights • The good crystallized Li 1+z/3 Ni 1/2-z/2 Ti 1/2+z/6 O 2 is prepared by a facile method. • The detailed redox process of Ni, Ti and O during the first cycle. • Stable structure and 0-TM network improve performance. • Li 1.17 Ni 0.25 Ti 0.58 O 2 exhibits high capacities and good rate capability. [ABSTRACT FROM AUTHOR]

The LiNi0.5Mn1.5O4 ||Li4Ti5O12 (LMNO||LTO) battery possesses a relatively-high energy density and cycle performance, with further enhancement possible by application of an AlF3 coating on the LTO electrode particles. We measure the performance enhancement to the LMNO||LTO battery achieved by a AlF3 coating on the LTO particles through electrochemical testing and use in-operando neutron powder diffraction to study the changes to the evolution of the bulk crystal structure during battery cycling. We find that the AlF3 coating along with parasitic Al doping slightly increases capacity and greatly increases rate capability of the LTO electrode, as well as significantly reducing capacity loss on cycling, facilitating a gradual increase in capacity during the first 50 cycles. Neutron powder diffraction reveals a structural response of the LTO and LNMO electrodes consistent with a greater availability of lithium in the battery containing AlF3-coated LTO. Further, the coating increases the rate of structural response of the LNMO electrode during charge, suggesting faster delithiation, and enhanced Li diffusion. This work demonstrates the importance of studying such battery performance effects within full configuration batteries.

Layered Ni-rich Li[Ni 0.6 Mn 0.2 Co 0.2- x Sn x ]O 2 cathode active materials with x  = 0–0.05 are synthesized via a co-precipitation synthesis route and the effect of doping content on the structural behavior and electrochemical performance are investigated. All synthesized materials show a well-defined layered structure of the hexagonal α -NaFeO 2 phase (space group R 3 ¯ m ) analyzed by X-ray diffraction (XRD). Electrochemical Li-metal/cathode cell studies exhibit that a Sn-content of 1%–2% is beneficial regarding specific discharge capacity and cycle life (≥20%). Detailed electrochemical investigations of Li-metal and lithium ion cells with cathodes consisting of LiNi 0.6 Mn 0.2 Co 0.2 O 2 and LiNi 0.6 Mn 0.2 Co 0.18 Sn 0.02 O 2 are conducted. Post mortem analyses by means of ICP-OES and TXRF show beneficial effects of the Sn-doping with regard to a lower transition metal dissolution and a higher available Li content in the cathode active material. The thermal analyses (TGA, DSC, ARC) show a stabilizing effect of Sn-doping, which results from a lower mass loss and less heat evolution of the charged cathode active materials at elevated temperatures. [ABSTRACT FROM AUTHOR]

The homogeneous nano-CeO 2 coated on the LiNi 1/3 Co 1/3 Mn 1/3 O 2 powder like substrate was prepared via a novel hydrolytic precipitation reaction followed by the thoroughly baking at 450 °C. The chemical composite of nano-CeO 2 coating layer was spectroscopically examined by X-ray diffraction, field-emission scanning electron microscopy and X-ray photoelectron spectrometer. The electrochemical characterization of the resulting materials proclaim that nano-CeO 2 coating can drastically improve lithium storage performances. The optimum coating amount of CeO 2 is as high as 2 wt%, which rendered a discharge capacity of 148.9 mAh g −1 with 91.6% capacity retention ensuing as many as 100 cycles. In particular, the exothermic peak is vastly increased from 256.4 to 338.2 °C. The value is superior to its counterparts, LiNi 1/3 Co 1/3 Mn 1/3 O 2 . It paves a new avenue for developing high safety lithium batteries. [ABSTRACT FROM AUTHOR]

A new three-dimensional (3D) sandwich-like Si/Polyaniline/Graphene nanoarchitecture anode for lithium ion batteries (LIBs) is successfully fabricated through an easy approach. In this nanoarchitecture, the in-situ polymerized electronic conductive polyaniline (PAni) hydrogel, acting as “glue”, agglutinates tightly to both the silicon nanoparticles (SiNPs) and graphene sheets, forming efficient conductive networks with high elastic modulus and high tensile strength. This mechanically robust nanoarchitecture can endure the great volume change of silicon and retain structural stability during Li-ion insertion/extraction. The electrodes consisting of this 3D sandwich-like Si/Polyaniline/Graphene nanoarchitecture reveal excellent electrochemical performance. The progress made in this work provides an easy and scalable route for preparing Si-based anode materials with high performance for advanced LIBs. [ABSTRACT FROM AUTHOR]

The charge/discharge mechanism and electrochemical performance of Zn 3 V 3 O 8 as anode for Li-ion batteries are systematically studied. Theoretical calculation predicts that Zn 3 V 3 O 8 can act as a host for Li storage, and a possible diffusion way of Li-ions within the crystal structure is calculated via first principle methods. Experimentally, Zn 3 V 3 O 8 nanosheets with porous architecture are fabricated via a facile hydrothermal pretreatment and subsequent sintering. The Zn 3 V 3 O 8 shows superior electrochemical performance with graphite electric additive, exhibiting discharge/charge capacity of 541/537 mAh g −1 after 200 cycles at a specific current of 120 mA g −1 . The Li-storage mechanism is also studied via ex-situ XRD, and the maintenance of main diffraction peaks during lithiation/delithiation process suggests a possible intercalation/extraction mechanism of the Zn 3 V 3 O 8 . [ABSTRACT FROM AUTHOR]

Li-rich layered cathode materials have been considered the most promising candidates for large-scale Li-ion batteries due to their low cost and high reversible capacity. However, these materials have many drawbacks that hinder commercialization, such as low initial efficiency and cyclability at elevated temperatures. To overcome these barriers, we propose an efficient and effective surface modification method, in which chemical activation (acid treatment) and LiCoPO coating were carried out simultaneously. During the synthesis, the lithium ions were extracted from the lattice, leading to improved Columbic efficiency, and these ions were used for the formation of LiCoPO. The Ni and Co doped spinel phase was formed at the surface of the host material, which gives rise to the facile pathway for lithium ions. The LiCoPO and highly doped spinel on the surface acted as double protection layers that effectively prevented side reactions on the surface at 60 °C. Moreover, the transition metal migration of the modified cathode was weakened, due to the presence of the spinel structure at the surface. Consequently, the newly developed Li-rich cathode material exhibited a high 1st efficiency of 94%, improved capacity retention of 82% during 100 cycles at 60 °C, and superior rate capability of 62% at 12C (1C = 200 mA/g) rate at 24 °C. In addition, the thermal stability of the modified cathode was significantly improved as compared to that of a bare counterpart at 4.6 V, showing a 60% decrease in the total heat generation. [ABSTRACT FROM AUTHOR]

Chromium nitride (CrN) synthesized by heating at 550 °C under a continuous stream of ammonia has been investigated as anode material for lithium electrochemistry. Due to its low lithium insertion potential, Cr is an attractive material for lithium–ion battery application, but the usual volume variation effect obstructs its practical use. In this study, different concentrations of carbon nanotubes doped with nitrogen (NCNTs) are combined with CrN to attain high electrochemical performance. The synthesized CrN/0.08%–NCNTs nanocomposite demonstrates network structure with 30–40 nm CrN nanoparticles anchored to specific sites on 40–60 nm diameter NCNTs. Upon electrochemical testing, CrN/0.08%–NCNTs nanocomposite displays a discharge capacity of 1172 mAh g −1 after 200 cycles with high coulombic efficiency (∼100%) and rate capability. The electrode can deliver a reversible capacity of 1042.9 mAh g −1 at 20 C. The n-type concentration, along with the conductive CNTs framework, mesoporous channels, appropriate surface area and buffering capability of CNTs, are together responsible for the excellent electrochemical performance. The electrochemical reaction mechanism of CrN with lithium is explored by investigating the structural changes using ex situ X-ray photoelectron spectroscopy, X-ray diffraction, selected area electron diffraction, and high-resolution transmission electron microscopy. The reversible conversion reaction of CrN into Cr metal and Li 3 N is revealed. [ABSTRACT FROM AUTHOR]

Pristine and yttrium-doped LiNi 0.5- x Y x Mn 1.5 O 4 spinel powders ( x = 0, 0.005, 0.01, 0.02, 0.04) were synthesized by a facile solid-state method. The effect of yttrium doping content on the electrochemical properties of LiNi 0.5- x Y x Mn 1.5 O 4 was investigated by using half-cells paired with lithium metal and full-cells paired with graphite. XRD and FT-IR analysis shows that the cation disordering degree (Mn 3+ content) first increase ( x ≤ 0.02) and then decrease with Y doping content and the Y doping can effectively inhibit the formation of Li x Ni 1- x O impurity phase. Electrochemical results show that in half-cells, the LiNi 0.5-x Y x Mn 1.5 O 4 cathode material with appropriate Y doping ( x = 0.01) exhibits optimal rate capability and cycling stability, due to higher phase purity, enlarged lattice parameter, higher disordering degree, higher structural stability by introducing Y O bond, lower charge transfer resistance and higher lithium ion diffusion coefficient, although the 0.2C discharge capacity is slightly lower than pristine LiNi 0.5 Mn 1.5 O 4 . Atomic Absorption Spectroscopy result shows that appropriate Y doping can effectively decrease the transition metal dissolution to certain extent, despite of higher Mn 3+ content. All above factors lead to the improved cycling performance of Y-doped electrode in half-cells paired with metallic Li at elevated temperature (55 °C) and in full-cells paired with graphite at room temperature. [ABSTRACT FROM AUTHOR]

In this work a novel pulse combustion reactor method for preparation of Li-ion cathode materials is introduced. Its advantages and potential challenges are demonstrated on two widely studied cathode materials, LiFePO 4 /C and Li-rich NMC. By exploiting the nature of efficiency of pulse combustion we have successfully established a slightly reductive or oxidative environment necessary for synthesis. As a whole, the proposed method is fast, environmentally friendly and easy to scale. An important advantage of the proposed method is that it preferentially yields small-sized powders (in the nanometric range) at a fast production rate of 2 s. A potential disadvantage is the relatively high degree of disorder of synthesized active material which however can be removed using a post-annealing step. This additional step allows a further tuning of materials morphology as shown and commented in some detail. [ABSTRACT FROM AUTHOR]

The composite of Co 3 O 4 , Co and graphitized carbon is synthesized by carbonization and cobalt-catalyzed-graphitization of carboxymethyl chitosan, followed by low-temperature thermal oxidation. At the high temperature, the Co(+2) is reduced to metallic Co and the produced Co acts as a catalyst for the graphitization of the pyrolytic carbon. The low-temperature oxidation is conducted to selectively oxidize Co to Co 3 O 4 while the carbon remains unreacted. The structure analysis indicates that three crystal phases (graphite, metallic Co, Co 3 O 4 ) accompanied with amorphous carbon are co-existed in the composite. Morphological results demonstrate that a lot of graphite grains around the Co element are distributed in the carbon. The electrochemical testing results indicate that the composite shows good electrochemical performance. It delivers a reversible capacity of 843 mAh g −1 at low current density, and remains 88.9% after 60 cycles at 200 mA g −1 . Even performed at 1 A g −1 , it also exhibits 493 mAh g −1 . The performance improvement is mainly due to the high capacity of Co 3 O 4 , high conductivity of graphitic carbon and metallic cobalt, the porous structure offering enough ion transport pathways and relieving the strain during cycling. [ABSTRACT FROM AUTHOR]

As a high-capacity hydrogen storage material, MgH 2 also shows specific advantages for LIB anode. In this work, MgH 2 and MgH 2 -C films were prepared by magnetron sputtering and hydrogenation treatment, and their microstructural and electrochemical properties were investigated. Through the conversion reaction of MgH 2 with lithium (MgH 2 + 2Li + → Mg + 2LiH), the reversible lithium storage was achieved in the MgH 2 and MgH 2 -C films. The MgH 2 film delivers the initial discharge capacity of 313.9 μAh cm −2 (∼2956 mAh g −1 ), the discharge and charge capacities related to the conversion process are respectively 150.0 μAh cm −2 (∼1412 mAh g −1 ) and 55.0 μAh cm −2 (∼518 mAh g -1 ), with the inefficiency of 63.3%. The GITT measurement determined the equilibrium potential of this conversion reaction to be 0.55 V vs. Li/Li + , and the voltage hysteresis between discharge and charge is only 10 mV vs. Li/Li + . In comparison with the MgH 2 film, the MgH 2 -C film has smaller crystallite size, lower polarization effect and structural stability, but exhibiting lower capacity and equally poor cyclic performance. The poor cycle life of MgH 2 -C film electrode is due to the large irreversibility of conversion reaction of MgH 2 , instead of structural damage of film electrode during cycling. [ABSTRACT FROM AUTHOR]

Particle morphology structure design combined with surface modification has been applied to improve the electrochemical properties of lithium rich layered oxides. Hollow spherical lithium rich layered Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 oxides with different shell thickness are synthesized by co-precipitation followed by calcination. The morphology and interior structure have been investigated by SEM and cross section, and their electrochemical properties have been evaluated to identify an appropriate shell thickness. Furthermore, a Zr compound coating layer has been applied to modify the interface between corrosive electrolyte and hollow spherical particles with an appropriate shell thickness. The Electrochemical impedance spectroscopy shows hollow spherical structure and Zr compound coating layer both can modificate the electronic and ionic transmission capacities and inhibit their deterioration during charge-discharge process at the same time. The HRTEM tests indicate that hollow spherical structure and Zr compound coating layer can dramatically suppress Mn dissolution in electrolyte and make the crystal structure more stable during the electrode process. Therefore, a surface modification combine with the hollow spherical structure (with an appropriate shell thickness) can effectively enhance these electrochemical properties of lithium ion layered oxides. [ABSTRACT FROM AUTHOR]

New self-supported poly(vinylidene fluoride)/poly (vinyl chloride-co-vinyl acetate) (PVdF/P(VC-VAc)) blended polymer membranes are prepared via a phase inversion method, and then their electrochemical performances, immersed in the liquid electrolyte as the polymer electrolyte for lithium-ion batteries (LIBs), are evaluated. The Fourier transform infrared spectroscopy analysis, the differential scanning calorimeter test and the X-ray diffraction measurement demonstrate that homogeneous PVdF/P(VC-VAc) polymer composites can form at all blend compositions and the crystallinity degree of the blended polymers decreases as the P(VC-VAc) content increases. Specifically, when the proportion of PVdF/P(VC-VAc) is 70:30 (wt%), membranes with a rich surface and internal porous structure can be acquired. The ionic conductivity of the polymer electrolyte achieves a maximum value of 3.57 mS cm-1 at room temperature, and favourable electrochemical performances of LIBs can be obtained. LiNi0.5Mn1.5O4/Li cells with the as-prepared polymer electrolyte exhibit a higher initial discharge capacity of 131.0 mAh g-1 and superior cycle stability with a capacity retention of 96.1% at 0.2 C after 200 cycles compared to cells based on pure PVdF and P(VC-VAc) membranes. This can be attributed to the superior compatibility of the electrolyte with the electrodes. The results also indicate this electrolyte has promising applications in high-voltage LIBs. [ABSTRACT FROM AUTHOR]

FeCO 3 with the morphology of microspheres and rice-like were successfully fabricated by a facile mixed solvothermal method by using urea and ammonium bicarbonate as precipitants, respectively. The as-synthesized samples were characterized by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The electrochemical properties of the samples were investigated by battery testing system. The influences of different precipitants on its structure, morphology and the electrochemical properties were also discussed. The results showed that the diameter of FeCO 3 microspheres (FCO-1) was 8–10 μm by using urea as precipitant, while the size of FeCO 3 rice-like (FCO-2) by using ammonium bicarbonate as precipitant was 0.5–1.0 μm. When used as an anode material for lithium ion batteries, FCO-1 and FCO-2 delivered the initial specific discharge capacities of 1563.54 and 1518.09 mAh g −1 at the current density of 100 mA g −1 in the voltage range of 0.01–3 V and remained its reversible value of 854.65 and 1019.47 mAh g −1 over 100 cycles, respectively. The FCO-2 still possessed a considerable capacity of 890.23 mAh g −1 at a high current density of 500 mA g −1 . Therefore, FCO-2 synthesized through using ammonium bicarbonate as precipitant could be a potential anode candidate for lithium ion batteries. [ABSTRACT FROM AUTHOR]

Temperature dependent fabrication of NiCr 2 O 4 is studied and the application of the as-prepared NiCr 2 O 4 in both half-cell with Li metal anode and full-cell with LiFePO 4 cathode are assessed. When mixing with natural graphite (NG), the NiCr 2 O 4 obtained at 550 °C can deliver initial charge and discharge capacities of 795 and 1275.5 mAh g −1 at a specific current of 150 mA g −1 , maintaining of 939 and 955 mAh g −1 after 140 cycles. In contrast, after 140 cycles at the same specific current, the NiCr 2 O 4 obtained at 450 °C and 650 °C can maintain charge/discharge capacities of 800/814 and 523/528 mAh g −1 , respectively. When matching with a LiFePO 4 cathode, The NiCr 2 O 4 /NG (obtained at 550 °C) electrode delivers initial discharge capacity of 285 mAh g −1 , which maintains of 106 mAh g −1 after 50 cycles at a specific current of 100 mA g −1 . [ABSTRACT FROM AUTHOR]

Micron-sized Co 3 O 4 hollow powders consisting of size controlled hollow nanospheres are prepared by applying Ostwald ripening and Kirkendall effect to the spray pyrolysis process. The Co-C composite powders uniformly dispersed with different sizes of metallic Co nanocrystals are formed by reduction of the cobalt oxide-carbon composite powders prepared using spray pyrolysis. Subsequent oxidation of the Co-C composite powders with filled structures forms the micron-sized Co 3 O 4 hollow powders consisting of size controlled hollow nanospheres. The mean sizes of the Co 3 O 4 hollow nanospheres oxidized from Co-C composite powders formed at reduction temperatures of 400, 600, and 800 °C are 37, 55, and 73 nm, respectively. The discharge capacities of the Co 3 O 4 powders formed from the Co-C composite powders reduced at temperatures of 400, 600, and 800 °C for the 300 th cycle are 644, 702, and 660 mA h g −1 , respectively, and their capacity retentions calculated from the second cycle are 81, 86, and 84%, respectively. The porous-structured Co 3 O 4 powders formed from the Co-C composite powders reduced at 800 °C show slightly better rate performance than those of the other two samples. [ABSTRACT FROM AUTHOR]

Ionic liquids are often named solvents of the future because of flexibility in design. This statement has given credence that ionic liquids should simply replace the problematic electrolytes of lithium batteries. As a result, the promising potentials of ionic liquids in electrochemical systems are somehow obscured by inappropriate expectations. We summarize recent advancements in this field, especially, ionic liquids as standalone electrolytes, additives, plasticizers in gel polymer electrolytes, and binders; and attempt to shed light on the future pathway of this area of research. Ionic liquids are not dilute media to serve as pure solvents in electrochemical systems where mobility of ions is the priority; instead, they can contribute to the ionic conductivity of various components in a battery system. Owing to the enormous possibilities of ionic liquids, it is not merely a matter of choice. Ionic liquids can be used to design novel types of electrolytes for a new generation of lithium batteries. A promising possibility, which is still at a very early stage, is supercooled ionic liquid crystals for fast ion diffusion through the guided channels of a liquid-like medium. This, of course, will be a breakthrough in the realm of electrochemistry, far beyond lithium battery field, when materialized. [ABSTRACT FROM AUTHOR]

We have studied the effect of final annealing temperature on the formation of lithium zinc titanate, its electrical conductivity, and its electrochemical performance. LiZnTiO has been shown to form in a wide range of annealing temperatures, from 673 to 1073 K. Its particle size increases systematically with increasing annealing temperature, whereas its conductivity decreases. The highest electrochemical capacity at low currents is offered by the materials annealed at 773 and 873 K, and the highest cycling stability is offered by the material prepared at 873 K. [ABSTRACT FROM AUTHOR]

MoO 2 has gained renewed attention as a safe oxide anode host material for lithium ion insertion because of its high gravimetric/volumetric capacity and highly stable cycling behavior. However, these recent results are completely contrary to previous reports. To confirm that MoO 2 is an appropriate anode material as well as further understand lithium ion reactions when inserted into MoO 2 , we combine electrochemical characterization of MoO 2 electrodes and ex situ X-ray diffraction analysis with first principle calculations. Theoretical capacity of the MoO 2 electrode (∼209 mAh g −1 ) and stable capacity retention up to 100 cycles are simultaneously attained using a proper particle size and type of binder. Ex situ XRD analysis with first principle calculations of the phase transformation of MoO 2 electrodes shows that MoO 2 undergoes reversible structural changes upon lithiation and subsequent delithiation, clearly demonstrating that nanostructured MoO 2 can be used as an anode material for highly reliable lithium ion batteries. [ABSTRACT FROM AUTHOR]

In this work we compare electrochemical cycling stability of Fe containing Li rich phase Li 1.2 Ni 0.13 Fe 0.13 Mn 0.54 O 2 (Fe–Li rich) with the well-known Co containing Li rich composition Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 (Co–Li rich). During the first charge, the activation plateau corresponding to removal of Li 2 O from the structure is smaller (removal of 0.6 Li) in the case of Fe–Li rich compared to Co–Li rich composition (0.8 Li removal). Consequently, the Fe compound shows better capacity retention; for example, after 100 cycles Fe–Li rich compound exhibits 20% capacity degradation where as it is about 40% in the case of Co–Li rich phase. The electrochemical and microscopy studies support the fact that compared to Co–Li rich compound, the Fe–Li rich composition display smaller voltage decay and reduced spinel conversion. XPS studies on charged/discharged Fe–Li rich samples show participation of Fe +3 /Fe +4 redox during electrochemical cycling which is further supported by our first principles calculations. Also the temperature dependent magnetic studies on charge-discharged samples of Fe–Li rich compound point out that magnetic behavior is sensitive to cation oxidation states and Ni/Li disorder. [ABSTRACT FROM AUTHOR]

The spinel LiMnO was prepared by a one-step hydrothermal method using acetone as the reductant under different hydrothermal temperatures. X-ray diffraction and scanning electron microscopy analysis indicated that optimal LiMnO particles (LMO-120) were synthesized at the temperature of 120°C and the particles were well distributed and about 410 nm in size. Electrochemical performance showed that the as-prepared LiMnO particles exhibited a higher initial discharge capacity than commercial LiMnO (131.5 mAh g versus 115.6 mAh g at 0.2 C). An excellent discharge capacity retention rate of 94.07% was observed after 60 charge-discharge cycles. On the other hand, when cycled at the high rate of 1 C, the optimal LiMnO in this work showed a high discharge capacity of 107.5 mAh g in contrast to only 92.3 mAh g of the commercial LiMnO. These results indicate that LMO-120 showed excellent electrochemical performance, especially the prolonged cycling life and high-rate performance, which suggested that this spinel LiMnO has promise for practical application as a high-rate cathode material for lithium ion batteries. [ABSTRACT FROM AUTHOR]

Li 2 FeSiO 4 was synthesized through Sol–Gel method and the effect of calcination temperature, time and chelating agent concentration were investigated. Appropriate calcination temperature above 550 °C was determined by TG/DTA analysis. Afterward, the dried gel powder was calcined at each temperature of 650 °C, 700 °C and 750 °C for 1, 2 and 3 h. XRD studies illustrated the most appropriate calcination temperature of 700 °C for 1 h. To compare the effect of chelating agent concentration, citric acid with molar ratio of 1/3, 2/3 and 1 were used which 1/3 was determined as the best concentration. FE-SEM observation showed that mean grain is size lower than 100 nm. By using this material, a three electrodes test cell was assembled and its electrochemical properties were investigated. The results showed high charge capacity which could be achieved at current density of 0.05C. [ABSTRACT FROM AUTHOR]

Introducing the Mg ion into host lattice is applied to improving the electrochemical performance of LiNi 0.6 Co 0.2 Mn 0.2 O 2 . The effect of Mg substitution for Co on the structure, morphology, electrochemical properties and Li + diffusion coefficients are investigated in details. Rietveld refinement results reveal that Mg is incorporated into the bulk lattice, which results in reduced cation mixing and expand c -lattice parameter. All Mg-doped sample exhibit better cycle and rate performances, although the Mg substitution for Co led to decreasing a part of capacity. The Li diffusion coefficients obtained by galvanostatic intermittent titration technique (GITT) are increased with increases of Mg content. [ABSTRACT FROM AUTHOR]

A novel air-stable titanium hexacyanoferrate (Ti 0.75 Fe 0.25 [Fe(CN) 6 ] 0.96 ·1.9H 2 O) with a cubic structure is synthesized simply by a solution precipitation method, which is first demonstrated to be a scalable, low-cost anode material for lithium-ion batteries exhibiting high capacity, long cycle life and good rate capability. Nevertheless, it has a low capacity of about 100 mAh g −1 as an anode material for sodium-ion batteries. [ABSTRACT FROM AUTHOR]

We report a facile process to synthesize Mo 0.91 W 0.09 S 2 /amorphous carbon composites with mean thickness of only 5 nm ultrathin nanosheets and their improved electrochemical performance as anode materials for lithium ion batteries (LIBs). Structural and morphological characterizations of the nanocomposite have been investigated by XRD, SEM and TEM. It was found the amorphous carbon to be well dispersed on the ultrathin nanosheets surface. Due to the increased interlayer distance and the synergistic effects between Mo 0.91 W 0.09 S 2 nanosheets and amorphous carbon, the as-prepared Mo 0.91 W 0.09 S 2 /C electrode deliveres exhibit a high Li capacity, an excellent rate capability, and a stable cycling performance, which suggests the Mo 0.91 W 0.09 S 2 /C composites as promising electrode material for LIBs. [ABSTRACT FROM AUTHOR]