Excellent cycling stability of spherical spinel LiMn2O4 by Y2O3 coating for lithium-ion batteries

The Y₂O₃ nano-film is coated on the surface of the spherical spinel LiMn₂O₄ by precipitation method and subsequent heat treatment at 550 °C for 5 h in air. The structure and performance of the bare LiMn₂O₄ and Y₂O₃-coated LiMn₂O₄ are characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive analysis X-ray spectroscopy, galvanostatic charge–discharge, cyclic voltammetry, and impedance spectroscopy. It has been found that the addition of Y₂O₃ does not change the bulk structure of LiMn₂O₄, and the thickness of the Y₂O₃ coating layer is approximate to 3.0 nm. The 1 wt% Y₂O₃-coated LiMn₂O₄ electrode reveals excellent cycling performance with 80.3 % capacity retention after 500 cycles at 1 C at 25 °C. When cycling at elevated temperature 55 °C, the as-prepared sample still shows 76.7 % capacity retention after 500 cycles. These remarkable improvements indicate that thin Y₂O₃ coating on the surface of LiMn₂O₄ is an effective way to improve the electrochemistry performance. Besides, the suppression of Mn dissolution into the electrolyte via the Y₂O₃ coating layer can be accounted for the improved performances.     

Effects of vanadium oxide coating on the performance of LiFePO4/C cathode for lithium-ion batteries

Journal of Solid State Electrochemistry - LiFePO4 cathode material is considered as prospective materials for lithium-ion batteries and attracted great interest because of excellent cyclic...     

Recent progress of surface coating on cathode materials for high-performance lithium-ion batteries

Lithium-ion batteries (LIB) have received substantial attention in the last 10 years,as they offer great promise as power sources that can lead to the electric vehicle (EV) revolution in the next 5 years.Since the cathode serves as a key component in LIB,its properties significantly affect the performance of the whole system.Recently,the cathode surface modification based on coating technique has been widely employed to enhance the electrochemical performances by improving the material conductivity,stabilising the physical structure of materials,as well as preventing the reactions between the electrode and electrolyte.In this work,we reviewed the present of a number of promising cathode materials for Li-ion batteries.After that,we summarized the very recent research progress focusing on the surface coating strategies,mainly including the coating materials,the coating technologies,as well as the corresponding working mechanisms for cathodes.At last,the challenges faced and future guidelines for optimizing cathode materials are discussed.In this study,we propose that the structure of cathode is a crucial factor during the selection of coating materials and technologies.     

High capacity and cycling stability of poly(diaminoanthraquinone) as an organic cathode for rechargeable lithium batteries

Poly(1,5‐diaminoanthraquinone) is synthesized by oxidative polymerization of diaminoanthraquinone monomers and investigated as an organic host for Li‐storage reaction. Benefiting from its high density of redox‐active, Li⁺‐associable benzoquinone groups attached to conducting polyaniline backbones, this polymer undergoes its cathodic reaction predominately through Li⁺‐insertion/extraction processes, delivering a very high reversible capacity of 285 mAh g^?1. In addition, the PDAQ polymer cathode exhibits an excellent rate capability (125 mAh g^?1 at 800 mA g^?1) and a considerable cyclability with a capacity retention of ～160 mAh g^?1 over 200 cycles, possibly serving as a sustainable, high capacity Li⁺ host cathode for Li‐ion batteries. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 235–238     

A modified hierarchical porous carbon for lithium/sulfur batteries with improved capacity and cycling stability

A hierarchical porous carbon material as the conductive matrix in the sulfur cathode for rechargeable lithium batteries is prepared by an in situ two-step activation method using sucrose as the carbon source, CaCO₃ as the template, and (CH₃COO)₂Cu·H₂O (Cu(Ac)₂) as the additive. The microstructure and morphology of the activated porous sulfur–carbon composite is characterized by means of X-ray diffraction, N₂ adsorption–desorption, and scanning electron microscopy. The functioning mechanism of the additive on the pore formation is investigated using thermogravimetric analysis. Our results establish that thermal decomposition of the nano-CaCO₃ template results in the formation of the hierarchical porous carbon structure, and addition of Cu(Ac)₂ influences the carbonization process in an un-homogeneous way through the copper ion–sucrose reaction, resulting in the volume increment of small mesopores. The sample obtained shows better sulfur dispersion in the active porous carbon than that synthesized without Cu(Ac)₂ involvement, which is attributable to the modified pore structure and enlarged pore volume. Thus, a better utilization of sulfur is achieved and the initial discharge capacity increases from 1,287 to 1,397 mAh g^?1. Furthermore, the Li-S battery shows improved cycle stability because of enhanced interaction between the sulfur and the small mesopore.     

Melamine-templated TiO2 nanoparticles as anode with high capacity and cycling stability for lithium-ion batteries

Journal of Solid State Electrochemistry - Titanium dioxide (TiO2) plays a vital role especially in the field of sustainable energy including photovoltaic, environmental remediation, energy storage...     

Carbon nanotubes/vanadium oxide composites as cathode materials for lithium-ion batteries

Journal of Sol-Gel Science and Technology - The carbon nanotubes/vanadium oxide composites have been prepared through a facile hydrothermal method. Morphology features of the samples are...     

Recent progress in rate and cycling performance modifications of vanadium oxides cathode for lithium-ion batteries

The emergency of high-power electrical appliances has put forward higher requirements for the power density of lithium-ion batteries.Vanadium oxides with large ...     

Core-shell structured 1,4-benzoquinone@TiO_2 cathode for lithium batteries

Organic carbonyl compounds are considered as promising candidates for lithium batteries due to their high capacity and environmental friendliness. However, they suffer from serious dissolution in the electrolyte, leading to fast capacity decay. Here we report core-shell structured 1,4-benzoquinone@titanium dioxide(BQ@TiO_2) composite as cathode for lithium batteries. The composite cathode can deliver a high discharge capacity of 441.2 mA h/g at 50 m A/g and a high capacity retention of 80.7% after 100 cycles. The good cycling performance of BQ@TiO_2 composite can be attributed to the suppressed dissolution of BQ,which results from the physical confinement effect of TiO_2 shell and the strong interactions between BQ and TiO_2. Moreover, the combination of ex situ infrared spectra and density functional theory calculations reveals that the active redox sites of BQ are carbonyl groups. This work provides an alternative way to mitigate the dissolution of small carbonyl compounds and thus enhance their cycling stability.     

Enhanced electrochemical performance of LiFePO4 of cathode materials for lithium-ion batteries synthesized by surfactant-assisted solvothermal method

Lithium iron phosphate (LiFePO₄) cathode materials were synthesized by the solvothermal method with the assistance of different surfactants. The influences of polyethylene glycol 2000 (PEG 2000), polyvinylpyrrolidone (PVP), and cetyltrimethyl ammonium bromide (CTAB) on the microstructure and electrochemical performance of LiFePO₄ were investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), electrochemical impedance spectroscopy (EIS), and charge/discharge measurements. The particle size of the LiFePO₄ synthesized with the assistance of PEG was uniform and showed a flat rhombohedron-like shape. The initial discharge specific capacity is up to 122.80 mAh/g with an initial coulombic efficiency of 95.50% at 0.1C. LiFePO₄ synthesized with PVP-assisted presents a porous structure with an initial discharge specific capacity of 91.01 mAh/g. LiFePO₄ synthesized with CTAB-assisted shows a flower-like morphology with an initial discharge specific capacity of 100.44 mAh/g. Though the initial discharge capacities of the LiFePO₄ materials prepared with the assistance of CTAB and PVP are lower than those of the LiFePO₄ prepared without the assistance of surfactant, the two materials exhibited excellent cyclic stability at 0.1C.

     

Improving cycling stability of Bi-encapsulated carbon fibers for lithium/sodium-ion batteries by Fe_2O_3 pinning

Bi draws increasing attention as anode materials for lithium-ion batteries and sodium-ion batteries due to its unique layered crystal structure,which is in favor of achieving fast ionic diffusion kinetics during cycling.However,the dramatic volume expansion upon lithiation/sodiation and an insufficient theoretical capacity of Bi greatly hinder its practical application.Herein,we report the Fe_2 O_3 nanoparticle-pinning Bi-encapsulated carbon fiber composites through the electrospinning technique.The introduction of Fe_2 O_3 nanoparticles can prevent the growth and aggregation of Bi nanoparticles during synthetic and cycling processes,re s pectively.Fe_2 O_3 with high specific capacity also contributes to the specific capacity of the composites.Consequently,the as-prepared Bi-Fe_2 O_3/carbon fiber composite exhibits outstanding long-term stability,which delivers reversible capacities 504 and 175 mAh/g after1000 cycles at 1 A/g for lithium-ion and sodium-ion batteries,respectively.     

LiNi0.8Co0.15Al0.05O2 coated by chromium oxide as a cathode material for lithium-ion batteries

Journal of Solid State Electrochemistry - LiNi0.8Co0.15Al0.05O2 (NCA) material was decorated with different contents of Cr2O3 (0.01–2 wt%) via a precipitation technique followed by...     

Microwave synthesis of Li_2FeSiO_4 cathode materials for lithium-ion batteries

A novel synthetic method of microwave processing to prepare Li_2FeSiO_4 cathode materials is adopted.The Li_2FeSiO_4 cathode material is prepared by mechanical ball-milling and subsequent microwave processing.Olivin-type Li_2FeSiO_4 sample with uniform and fine particle sizes is successfully and fast synthesized by microwave heating at 700℃in 12 min.And the obtained Li_2FeSiO_4 materials show better electrochemical performance and microstructure than those of Li_2FeSiO_4 sample by the conventional solids...     

Surface modified TiO2/reduced graphite oxide nanocomposite anodes for lithium ion batteries

Journal of Solid State Electrochemistry - Anatase TiO2 nanoparticles with an average crystallite size of ~ 20 nm are synthesized through a sol-gel method. A composite anode for...     

Modification of LiCoO2 through rough coating with lithium lanthanum zirconium tantalum oxide for high-voltage performance in lithium ion batteries

Journal of Solid State Electrochemistry - In this study, the spray-drying technique was used to apply a 0.5 at%, 1 at%, and 1.25 at% of lithium lanthanum zirconium tantalum oxide...     

Low-temperature synthesis of a green material for lithium-ion batteries cathode

Abstract

Battery technology is an important anthropogenic source of the heavy metals which are highly threatening to human health. A category of rechargeable lithium batteries that is of great interest is the set of batteries where the cathode material is a lithium iron phosphate (LiFePO₄). LiFePO₄ is an environmentally friendly and safe lithium-ion battery cathode material, but it has a key limitation, and that is its extremely low-electronic conductivity, a problem that can be greatly overcome by zinc-doping LiFePO₄. For the first time to our knowledge, a low-temperature method, that is advantageous both economically and technologically, for the synthesis of a zinc-doped LiFePO₄ is presented. Since the method appears to be applicable for synthesizing various zinc-doped LiFePO₄ compounds with the general formula LiFe_1?x Zn _x PO₄ (0<x<1), it is very promising for the production of a green cathode material for lithium-ion batteries.     

Combustion synthesized LiMnSnO4 cathode for lithium batteries

Novel category LiMnSnO₄ compound was synthesized via. Urea assisted combustion (UAC) method at 800 °C and examined for possible use as cathode material in lithium-ion batteries. The XRD (X-ray diffraction) results of LiMnSnO₄ sample authenticate the orthorhombic crystal structure with high degree of crystallinity. Presence of uniformly distributed nanometric grains (scanning electron microscopy) with preferred local cation environment is evident from FT IR (Fourier transform infra red spectroscopic) and ⁷Li NMR (nuclear magnetic resonance spectroscopy) studies. The charge–discharge behavior of Li/LiMnSnO₄ cells demonstrated a specific capacity of 113 mA h/g, with an excellent capacity retention (95%) and Ah efficiency (>99%). Besides, the internal resistance of the Li/LiMnSnO₄ cell after 30 cycles is negligibly small, thus demonstrating good electronic conductivity and cycling stability, required for any lithium intercalating cathode material.     

Intrinsic characteristics of cathode and anode materials for lithium-ion batteries

Fundamental aspects of solving the problem of how the working capacity of lithium-ion batteries in prolonged cycling can be raised and the basic tendencies in the relationship between the intrinsic parameters of active materials of various brands and the electrochemical behavior of anodes and cathodes fabricated from these materials are considered.