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Polypyrrole (PPy) used as popular coatings can improve the electrochemical performance of electrodes greatly; however, uniform coatings of PPy on nanostructures is a challenging task in a solution system. Substitution for liquid phase polymerization reaction, herein a developed evaporation method is reported to make pyrrole vapor in situ polymerization on CuO arrays for the uniform PPy coatings. With the help of this uniform PPy coatings, the unique structure of arrayed CuO film can well maintain the stability of mechanical structures and has rapid transmission of lithium ions and electrons during charge/discharge processes, hence harvesting a high lithium storage. Electrochemical tests indicate that PPy can not only enhance the specific capacities of CuO anodes greatly but also improve the cyclic stability at a high-current density. The specific capacity of the CuO@PPy integrated anode can be up to 561 mAh g−1 at 1 C after 100 cycles, which is increased by almost 33% than that of the pure CuO anode. [ABSTRACT FROM AUTHOR]

The structural and electrochemical effects of electrospun V2O5 with selected redox-inactive dopants (namely Na+, Ba2+ and Al3+) have been studied. The electrospun materials have been characterised via a range of analytical methods including X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller surface area measurements and scanning and transmission electron microscopy. The incorporation of dopants in V2O5 was further studied with computational modelling. Structural analysis suggested that the dopants had been incorporated into the V2O5 structure with changes in crystal orientation and particle size, and variations in the V4+ concentration. Electrochemical investigations using potentiodynamic, galvanostatic and impedance spectroscopy analysis showed that electrochemical performance might be dependent on V4+ concentration, which influenced electronic conductivity. Na+- or Ba2+-doped V2O5 offered improved conductivities and lithium ion diffusion properties, whilst Al3+ doping was shown to be detrimental to these properties. The energetics of dopant incorporation, calculated using atomistic simulations, indicated that Na+ and Ba2+ occupy interstitial positions in the interlayer space, whilst Al3+ is incorporated in V sites and replaces a vanadyl-like (VO)3+ group. Overall, the mode of incorporation of the dopants affects the concentration of oxygen vacancies and V4+ ions in the compounds, and in turn their electrochemical performance.ᅟ [ABSTRACT FROM AUTHOR]

The electrochemical performances of LiMnNiCoO cathode material are enhanced through hydrothermal approach using NaS solution as a medium. Furthermore, the influence of contents of NaS solution on the morphology, structure, and electrochemical performances is fully investigated. The results indicate that a high content of NaS solution results in the formation of spinel particles which are detected by SEM, XRD, and HR-TEM measurements. The formation of spinel particles leads to a deterioration of electrochemical performances. However, a low content of NaS solution results in a slight structure change from layered phase to spinel one near the edge of LiMnNiCoO particles. This slight structure change facilitates the decrease of charge transfer resistance, which contributes to the enhanced rate capability of NaS-treated LiMnNiCoO. [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]

LiZnTiO/C nanocomposite has been synthesized using phenolic resin as carbon source in this work. The structure, morphology, and electrochemical properties of the as-prepared LiZnTiO samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), Raman spectroscopy (RS), galvanostatic charge-discharge, and AC impedance spectroscopy. SEM images show that LiZnTiO/C was agglomerated with a primary particle size of ca. 40 nm. TEM images reveal that a homogeneous carbon layer (ca. 5 nm) formed on the surface of LiZnTiO particles which is favorable to improve the electronic conductivity and inhibit the growth of LiZnTiO during annealing process. The as-prepared LiZnTiO/C composite with 6.0 wt.% carbon exhibited a high initial discharge capacity of 425 and 159 mAh g at 0.05 and 5 A g, respectively. At a high current density of 1 A g, 95.5 % of its initial value is obtained after 100 cycles. [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]

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]

Natural graphite treated by mechanical activation can be directly applied to the preparation of LiV(PO). The carbon-coated LiV(PO) with monoclinic structure was successfully synthesized by using natural graphite as carbon source and reducing agent. The amount of activated graphite is optimized by X-ray diffraction, scanning electron microscope, transmission electron microscope, Raman spectrum, galvanostatic charge/discharge measurements, cyclic voltammetry, and electrochemical impedance spectroscopy tests. Our results show that LiV(PO) (LVP)-10G exhibits the highest initial discharge capacity of 189 mAh g at 0.1 C and 162.9 mAh g at 1 C in the voltage range of 3.0-4.8 V. Therefore, natural graphite is a promising carbon source for LVP cathode material in lithium ion batteries. [ABSTRACT FROM AUTHOR]

Used LiCoO material was renovated by means of ultrasound radiation under hydrothermal conditions. The optimal reaction condition for renovation process was obtained: temperature 120 °C, ultrasonic power 999 W, and ultrasonic method 'work 5 s-stop 2 s' and ultrasonic radiation time 10 h. The XRD, SEM, ICP-AES analysis, and charge-discharge test showed that the renovated LiCoO had a high degree of crystallinity, a fine-layered structure, good dispersion of particles, and improved electrochemical cycle performance. The first-time charge capacity and discharge capacity of renovated LiCoO were 132.6 and 131.5 mAh/g, respectively. The first-time charge and discharge efficiency was 99.2 %. After 20 cycles, the discharge capacity retention rate was 98.1 % which reaches or approaches the electrochemical properties of commercial batteries. [ABSTRACT FROM AUTHOR]

α-MoO nanobelts were synthesized by simple hydrothermal method and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Cyclic voltammogram (CV) and galvanostatic charge/discharge testing techniques were employed to evaluate electrochemical behaviors of α-MoO materials. Results showed that α-MoO nanobelts with about 80 nm in diameter and 5-12 μm in length were grown in the orthorhombic system. Electrochemical characterisation confirmed that in lithium ion insertion/extraction process, the first intercalation of lithium ion in α-MoO at about 2.8 V was irreversible, corresponding to LiMoO (0 < x ≤ 0.25) and the parent MoO materials coexisting, the second lithium ion inter-calation was reversible at the potential range of 2.2-2.4 V followed by LiMoO (0.25 < x ≤ 0.5), and below 1.0 V the mechanism of lithium ion storage changed from lithium ion intercalation reaction into lithium alloying reaction. The α-MoO nanobelts showed better electrochemical performance, 319 mA h g initial discharge capacity, around 52% capacity retention after 20 cycles than that of α-MoO bulk. [ABSTRACT FROM AUTHOR]

Carbon-coated LiMnSiO powders were synthesized by a citric acid-assisted sol-gel process, and their physical and electrochemical properties were characterized to assess their suitability as a cathode material in lithium-rechargeable batteries. Carbon was coated onto the LiMnSiO particles through the carbonization of polymeric materials that were caused by the addition of citric acid during the sol-gel process. The particle size and electrical conductivity of the LiMnSiO powders were found to be changed by varying the amount of citric acid added during the sol-gel process. XRD analysis showed that the quantity of impurities in LiMnSiO was decreased during the sol-gel process. The carbon coating led to an increase in conductivity and mean particle size by creating an electrical and physical connection between the particles. The discharge capacity of LiMnSiO with over 5 % carbon coating was significantly increased to ~125 mAh g compared to just ~3 mAh g for noncoated material. [ABSTRACT FROM AUTHOR]

Spinel LiMnO and multidoped spinel LiMnCoCrNiFeO were synthesized by the glycine-nitrate method and coated with lithium borosilicate (LBS) in order to enhance the electrochemical performance at room temperature. The structure and electrochemical performance of all samples were characterized by inductively coupled plasma-mass spectrometer (ICP-MS), X-ray diffraction (XRD), differential thermal analysis/thermogravimetry (DTA/TG), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), atomic force microscopy (AFM) and galvanostatic charge-discharge measurements. The XRD analysis shows that the samples exhibit a pure spinel phase. The SEM results indicated that LBS particles had encapsulated the surface of the undoped and multidoped LiMnO without causing any structural change. The charge-discharge tests showed that LiMnCoCrNiFeO displays better cycling performance than the pristine LiMnO at room temperature. However, in the same conditions, LBS-coated LiMnCoCrNiFeO and LiMn O have better cycling performance than uncoated samples. The results suggest that multidoped and LBS-coated LiMnO could develop into a promising cathode material for lithium ion batteries. [ABSTRACT FROM AUTHOR]

Red phosphorus (RP) has attracted extensive attention as an anodic material for lithium-ion batteries (LIBs) due to its high theoretical specific capacity of 2596 mA h g− 1 and earth abundance. However, the facile and large-scale preparation of the red phosphorus nanomaterials via a solution synthesis remains a challenge. Herein, we develop a simple and facile solution method to prepare red phosphorus nanoparticles (RP NPs). PCl3 readily reacts with HSiCl3 in the presence of amines at room temperature to produce amorphous RP NPs with sizes about 100-200 nm in high yields. When used as an anode for rechargeable lithium ion battery, the RP NP electrode exhibits good electrochemical performance with a reversible capacity of 1380 mA h g− 1 after 100 cycles at a current density of 100 mA g− 1, and Coulombic efficiencies reaching almost 100% for each cycle. The study shows that this solution synthesis is a facile and convenient approach for large-scale production of RP NP materials for use in high-performance Li-ion batteries. [ABSTRACT FROM AUTHOR]