Preparation of MnO2 and MnO2/carbon nanotubes nanocomposites with improved electrochemical performance for lithium ion batteries

Journal of Solid State Electrochemistry - Manganese dioxide (MnO2) nanomaterials and manganese dioxide/carbon nanotubes (MnO2/CNTs) nanocomposites were prepared by chemical precipitation and...     

CoO octahedral nanocages for high-performance lithium ion batteries

Pure-phase CoO octahedral nanocages were successfully fabricated by a novel simple method. The coordination etching agents play key roles in the formation of these non-spherical hollow structures. When tested as anode materials in lithium ion batteries (LIBs), these nanocages showed excellent cycling performance, good rate capability and enhanced lithium storage capacity.     

Polyimide-derived carbon nanofiber membranes as anodes for high-performance flexible lithium ion batteries

Heteroatoms-doped carbon nanofiber membranes with flexible features were prepared by electrospinning with heterocyclic polyimide (PI) structures containing biphenyl and pyrimidine rings. The products with optimized treatment could achieve 695 mAh/g at 0.1 A/g and retain 245 mAh/g at 1.5 A/g after 300 cycles when used as anode for Li-ion batteries.     

High capacity silicon/carbon composite anode materials for lithium ion batteries

Silicon/carbon composite materials are prepared by pyrolysis of pitch embedded with graphite and silicon powders. As anode for lithium ion batteries, its initial reversible capacity is 800–900 mAh/g at 0.25 mA/cm² in a voltage range of 0.02/1.5 V vs. Li. The material modification by adding a small amount of CaCO₃ into precursor improves the initial reversibility (η₁=84%) and suppresses the capacity fade upon cycling. A little higher insertion voltage of the composites than commercial CMS anode material improves the cell safety in the high rate charging process.     

Designing composite solid-state electrolytes for high performance lithium ion or lithium metal batteries

Solid-state electrolytes (SSEs) are capable of inhibiting the growth of lithium dendrites, demonstrating great potential in next-generation lithium-ion batteries (LIBs). However, poor room temperature ionic conductivity and the unstable interface between SSEs and the electrode block their large-scale applications in LIBs. Composite solid-state electrolytes (CSSEs) formed by mixing different ionic conductors lead to better performance than single SSEs, especially in terms of ionic conductivity and interfacial stability. Herein, we have systematically reviewed recent developments and investigations of CSSEs including inorganic composite and organic–inorganic composite materials, in order to provide a better understanding of designing CSSEs. The comparison of different types of CSSEs relative to their parental materials is deeply discussed in the context of ionic conductivity and interfacial design. Then, the proposed ion transfer pathways and models of lithium dendrite growth in composites are outlined to inspire future development of CSSEs.

Composite solid-state electrolytes (CSSEs) formed by mixing different ionic conductors lead to better performance than a single solid-state electrolytes (SSEs), demonstrating great potentials in the next-generation lithium-ion batteries (LIBs).     

Effect of oxidative stabilization on the electrochemical performance of carbon mesophases as electrode materials for lithium batteries

The effect of oxidative stabilization as a mean to modify the carbon texture was essayed in a group of mesophases previous to carbonization at 900 °C with the aim of evaluating the influence on electrochemical performance when used as electrode materials in lithium test cells. X-ray diffraction, optical microscopy and chemical analysis, Fourier-transform infrared spectroscopy have been used to describe the compositional and textural properties of the as-produced parent mesophases, the samples were further treated under air current to stabilize their microstructures and the corresponding carbonized samples at 900 °C. The electrochemical performance was determined by the galvanostatic method and further correlated to the physical–chemical properties and interface resistance of the materials. In all cases, the stabilization process has demonstrated a beneficial effect on the capacity retention in the measured range.     

Core-shell structured electrode materials for lithium ion batteries

Recent progress in studies of several types of core-shell structured electrode materials, including TiO₂/C, Si/C, Si/SiO _x , LiCoO₂/C, and LiFePO₄/C nanocomposites, including details of their preparation and their electrochemical performance is briefly reviewed. Results clearly show that the coating shell can effectively prevent the aggregation of the nanosized cores, which are the electrochemically active materials. In addition, the diffusion coefficients of lithium ions can be increased, and the reversibility of lithium intercalation and deintercalation is improved. As a result, the cycling behavior is greatly improved. The reviewed results suggest that core-shell nanocomposites are a good starting point for further development of new promising electrode materials.

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A selenium-doped carbon anode of high performance for lithium ion batteries

Journal of Solid State Electrochemistry - The strong demand on high-performance lithium ion batteries has brought up an attention upsurge in the research society and the commercial market. Carbon...     

SnO2 sheet/graphite composite as anode material with improved electrochemical performance for lithium-ion batteries

The SnO₂ sheet/graphite composite was synthesized by a hydrothermal method for high-capacity lithium storage. The microstructures of products were characterized by XRD and FE-SEM. The electrochemical performance of SnO₂ sheet/graphite composite was measured by galvanostatic charge/discharge cycling and EIS. The first discharge and charge capacities are 1,072 and 735 mAh g^?1 with coulombic efficiency of 68.6 %. After 40 cycles, the reversible discharge capacity is still maintained at 477 mAh g^?1. The results show that the SnO₂ sheet/graphite composite displays superior Li-battery performance with large reversible capacity and good cyclic performance.     

Hierarchical porous carbon derived from rice straw for lithium ion batteries with high-rate performance

Porous carbons with a high surface area have been prepared from rice straw. The hierarchical porous network with large macroporous channels and micropores within the channel walls enable the porous carbons to provide the pathways for easy accessibility of electrolytes and fast transportation of lithium ions. These porous carbons which show a particular large reversible capacity are proved to be promising anode materials for high-rate and high-capacity lithium ion batteries.     

Lithium manganese oxide with excellent electrochemical performance prepared from chemical manganese dioxide for lithium ion batteries

Chemical manganese dioxide (CMD) is synthesized by the SEDEMA process and adopted as a precursor for lithium manganese oxide with a spinel structure (LMO). LMO is also prepared from electrolytic manganese dioxide (EMD) as a reference for comparison. X-ray diffraction (XRD) shows that CMD is composed of γ-MnO₂, and scanning electron microscopy (SEM) with transmission electron microscopy (TEM) shows that the nanorods cover a spherical core with a diameter < 1 μm. The LMO prepared from CMD shows a much better rate capability and cycle life performance than that from EMD at high temperatures and high current densities. The excellent electrochemical performance is attributed to the structural stability during charge and discharge and the morphology of the LMO, a loose aggregation of the octahedral particles with a uniform size (<1 μm) and shape, which originated from that of CMD.     

Modified carbon cloth as positive electrode with high electrochemical performance for vanadium redox flow batteries

Carbon cloth modified by hydrothermal treatment in ammonia water is developed as the positive electrode with high electrochemical performance for vanadium redox flow batteries.The SEM shows that the treatment has no obvious influence on the morphology of carbon cloth.XPS measurements indicate that the nitrogenous functional groups can be introduced on the surface of carbon cloth successfully.The electrochemical performance of V（IV）/V（V） redox couple on the prepared electrode is evaluated with cyclic voltammetry and linear sweep voltammetry measurements.The N-doped carbon cloth exhibits outstanding electrochemical activity and reversibility toward V（IV）/V（V） redox couple.The rate constant of V（IV）/V（V） redox reaction on carbon cloth can increase to 2.27 × 10^-4cm/s from 1.47 × 10^-4cm/s after nitrogen doping.The cell using N-doped carbon cloth as positive electrode has larger discharge capacity and higher energy efficiency compared with the cell using pristine carbon cloth.The average energy efficiency of the cell using N-doped carbon cloth for 50 cycles at 30 m A/cm² is 87.8%,4.3% larger than that of the cell using pristine carbon cloth.It indicates that the N-doped carbon cloth has a promise application prospect in vanadium redox flow batteries.     

Effect of carbon sources on the electrochemical performance of Li2FeSiO4 cathode materials for lithium ion batteries

Li₂FeSiO₄ cathode materials have been prepared by sol-gel method. The effects of carbon sources on the structural, morphological and electrochemical behaviors of Li₂FeSiO₄ were investigated. The scanning electronic microscope (SEM) and X-ray diffraction powder analysis (XRD) indicate that the obtained samples using different carbon sources possess some difference in the morphology and in the particle size. The sample using the mixture of citric acid and oxalic acid as carbon source has a maximum discharge capacity of 118 mA h g^?1 at 0.1 C between 1.8 and 4.5 V. The resulting cyclic voltammograms and electrochemical impedance spectra suggest that the sample using mixed acid as carbon source has smaller polarization and smaller charge transfer impedance.     

In situ synthesis of MoS2/graphene nanosheet composites with extraordinarily high electrochemical performance for lithium ion batteries

A facile process was developed to synthesize MoS(2)/graphene nanosheet (GNS) composites by a one-step in situ solution-phase method. These MoS(2)/GNS composites therefore exhibit extraordinary capacity, i.e., up to 1300 mA h g(-1), and excellent rate capability and cycling stability as an anode material for lithium ion batteries.     

High capacity SnxSbyCuz composite anodes for lithium ion batteries

To increase the volumetric discharge capacity of negative electrode for rechargeable lithium batteries, a composite anode Sn_xSb_yCu_z has been synthesized by using high energy mechanical ball milling method. The synthesized composite anode materials have been characterized by X-ray diffraction and SEM analysis. The charge/discharge characteristics of the fabricated coin cells have been evaluated galvanostatically in the potential range 0.01–2 V using 1 M LiPF₆ in 1:1 EC/DEC as electrolyte. Results indicate that the composition with 90 wt% Sn, 8 wt% Sb and 2 wt% Cu delivers an average discharge capacity of 740 mAh g⁻¹ over the investigated 50 cycles which is a potential candidate for use as an anode material for lithium rechargeable cells.     

Porous structure SnSb/amorphous carbon core-shell composite as high capacity anode materials for lithium ion batteries

SnSb/C core-shell powder has been successfully prepared by modified carbothermal reduction method. The shape, size, morphology, and electrochemical properties of the SnSb/C core-shell powder have been investigated. SnSb particles are completely encapsulated by amorphous carbon shell, and the surface of SnSb/C composite has been characterized with porous structure. The composite has a relatively high BET surface area of 253 m²g^?1. The composite exhibits relatively good capacity retention for 50 cycles at a constant current density of 100 mA g^?1 and show excellent rate performance when the current ranges from 50 to 200 mA g^?1. The improvement of reversible capacity and cyclic performance is attributed to loose and amorphous surface structure which could buffer volume variations through cycle process.     

Functional porous carbon-based composite electrode materials for lithium secondary batteries

The synthetic routes of porous carbons and the applications of the functional porous carbon-based composite electrode materials for lithium secondary batteries are reviewed. The synthetic methods have made great breakthroughs to control the pore size and volume, wall thickness, surface area, and connectivity of porous carbons, which result in the development of functional porous carbon-based composite electrode materials. The effects of porous carbons on the electrochemical properties are further discussed. The porous carbons as ideal matrixes to incorporate active materials make a great improvement on the electrochemical properties because of high surface area and pore volume, excellent electronic conductivity, and strong adsorption capacity. Large numbers of the composite electrode materials have been used for the devices of electrochemical energy conversion and storage, such as lithium-ion batteries (LIBs), Li-S batteries, and Li-O2 batteries. It is believed that functional porous carbon-based composite electrode materials will continuously contribute to the field of lithium secondary batteries.     

Net-like SnS/carbon nanocomposite film anode material for lithium ion batteries

SnS particles with sizes of 5.0–6.5 nm were prepared by a facile method. Resorcinol–formaldehyde sol with addition of the as-prepared SnS nanoparticles was spin-coated on a copper foil to prepare net-like SnS/C composite thin-film electrode for lithium ion batteries after carbonization at 650 °C. The SnS/C nanocomposite thin-film electrode showed preferable first coulombic efficiency and excellent cycling stability. The discharge and charge capacities were respectively 542.3 and 531.3 mAh/g after 40 cycles. The attractive electrochemical performances were mainly ascribed to the ultra fine particle, which showed no evident aggregation in high-resolution TEM image, and the effects of 3-dimensional net-like carbon structure, which uniformly surrounded the SnS nanoparticles to guarantee the contact, acted as a buffer matrix to alleviate the volume expansion of Li–Sn alloy and provided enough paths for electrolyte to reach SnS active material during discharge–charge process.     

A novel network composite cathode of LiFePO4/multiwalled carbon nanotubes with high rate capability for lithium ion batteries

A novel network composite cathode was prepared by mixing LiFePO₄ particles with multiwalled carbon nanotubes for high rate capability. LiFePO₄ particles were connected by multiwalled carbon nanotubes to form a three-dimensional network wiring. The web structure can improve electron transport and electrochemical activity effectively. The initial discharge capacity was improved to be 155 mA h/g at C/10 rate (0.05 mA/cm²) and 146 mA h/g at 1C rate. The comparative investigation on MWCNTs and acetylene black as a conducting additive in LiFePO₄ proved that MWCNTs addition was an effective way to increase rate capability and cycle efficiency.