Electrochemical behavior of alpha-MoO3 nanorods as cathode materials for rechargeable lithium batteries

The electrochemical properties of alpha-MoO3 nanorods, which were synthesized via a solution-based method and following calcination, have been reported as a cathode material for rechargeable lithium batteries. Detailed lithium-insertion process of the material has been conducted by means of cyclic voltammetry, galvanostatic method, and impedance technique, and superior features associated with the nanostructures have been observed. The alpha-MoO3 nanorods exhibited an initial discharge capacity of 271.8 mAh/g under a current density of 0.1 mA/cm2 in the range 1.0 approximately 3.0 V, which nearly approached the theoretical capacity 280 mAh/g. Comparison of the structural and electrochemical characteristics with those of bulk alpha-MoO3 suggests the enhanced electrochemical performance might be related to the rodlike structure and increased edge and corner effects.     

Dispersed materials for rechargeable lithium batteries: Reactive and non-reactive grinding

Reactive and non-reactive grinding has been used to prepare high dispersed lithium-transition metal cathode materials (LiMn₂O₄, LiCoO₂, LiV₃O₈, Li₃Fe₂(PO₄)₃, LiTi₂(PO₄)₃) and inorganic solid state Li-ion electrolytes (Li_1.3Al_0.3Ti_1.7(PO₄)₃) for rechargeable lithium batteries. Submicron particle size and the presence of cationic vacancies and cationic disordering positively influence electrochemical properties of as prepared cathodes, leading to larger practical capacity and stability upon intercalation-deintercalation of lithium ions. However, the advantages are observed only when the first electrochemical step is an insertion of Li⁺ ions (Li battery discharge). The conductivity of the Li_1.3Al_0.3Ti_1.7(PO₄)₃ lithium ion electrolyte prepared by using MA was of 2-3 order of magnitude higher than that for nonactivated sample owing to the absence of non-conductive impurities and lower grain boundary resistance.     

Functional materials for rechargeable batteries

There is an ever-growing demand for rechargeable batteries with reversible and efficient electrochemical energy storage and conversion. Rechargeable batteries cover applications in many fields, which include portable electronic consumer devices, electric vehicles, and large-scale electricity storage in smart or intelligent grids. The performance of rechargeable batteries depends essentially on the thermodynamics and kinetics of the electrochemical reactions involved in the components (i.e., the anode, cathode, electrolyte, and separator) of the cells. During the past decade, extensive efforts have been dedicated to developing advanced batteries with large capacity, high energy and power density, high safety, long cycle life, fast response, and low cost. Here, recent progress in functional materials applied in the currently prevailing rechargeable lithium-ion, nickel-metal hydride, lead acid, vanadium redox flow, and sodium-sulfur batteries is reviewed. The focus is on research activities toward the ionic, atomic, or molecular diffusion and transport; electron transfer; surface/interface structure optimization; the regulation of the electrochemical reactions; and the key materials and devices for rechargeable batteries.     

Organic materials for rechargeable sodium-ion batteries

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Polymer-graphene nanocomposites as ultrafast-charge and -discharge cathodes for rechargeable lithium batteries

Electroactive polymers are a new generation of "green" cathode materials for rechargeable lithium batteries. We have developed nanocomposites combining graphene with two promising polymer cathode materials, poly(anthraquinonyl sulfide) and polyimide, to improve their high-rate performance. The polymer-graphene nanocomposites were synthesized through a simple in situ polymerization in the presence of graphene sheets. The highly dispersed graphene sheets in the nanocomposite drastically enhanced the electronic conductivity and allowed the electrochemical activity of the polymer cathode to be efficiently utilized. This allows for ultrafast charging and discharging; the composite can deliver more than 100 mAh/g within just a few seconds.     

Lattice vibrations of materials for lithium rechargeable batteries. VI: Ordered spinels

Raman scattering spectra have been investigated to evaluate the local structure of lithiated oxides used as electrode materials for lithium-ion batteries. We report the analysis of the vibrational spectra of ordered spinel phases including the partially delithiated λ-Li_0.5Mn₂O₄ ( SG), the partial charge-ordered LiMn₂O₄ orthorhombic form (Fddd SG) and the LiNi_0.5Mn_1.5O₄ substituted oxide (P4₁32 SG). Analysis of spectroscopic data is performed using the classical factor group theory and the vibration features are compared with those of the ordered lithium ferrite -LiFe₅O₈ and the normal spinels LiMn₂O₄ and LiNi_0.5Mn_1.5O₄ (Fd3m SG), and the inverse spinel LiNiVO₄.     

锂离子电池正极材料硫化聚丙烯腈的研究进展

用单质硫和聚丙烯腈进行硫化,可以制备具有电化学活性的导电高分子材料硫化聚丙烯腈.这种材料用作锂离子电池正极活性材料,可以获得较高的比容量和较长的循环寿命.本文综述了硫化聚丙烯腈的研究进展和可能的储锂机理,并提出了进一步改进性能的方法.     

Mechanochemical synthesis of SnO-B2O3 glassy anode materials for rechargeable lithium batteries

The xSnO·(100 ? x)B₂O₃ (0 ≦ x ≦ 80) glasses were successfully prepared by a mechanical milling technique. The glass with 40 mol% SnO showed the maximum glass transition temperature of 347°C. The SnO-B₂O₃ milled glasses consisted of both BO₃ and BO₄ units, and the fraction of BO₄ units was maximized at the composition of 50 mol% SnO. The electrochemical properties of the milled glasses were examined using a simple three electrodes cell with a conventional liquid electrolyte. The glasses with high SnO content exhibited high charge capacities more than 1100 mAh g^?1 and discharge capacities more than 700 mAh g^?1 at the first cycle. The SnO-B₂O₃ milled glasses proved to work as anode materials for rechargeable lithium batteries.     

Large reversible Li storage of graphene nanosheet families for use in rechargeable lithium ion batteries

The lithium storage properties of graphene nanosheet (GNS) materials as high capacity anode materials for rechargeable lithium secondary batteries (LIB) were investigated. Graphite is a practical anode material used for LIB, because of its capability for reversible lithium ion intercalation in the layered crystals, and the structural similarities of GNS to graphite may provide another type of intercalation anode compound. While the accommodation of lithium in these layered compounds is influenced by the layer spacing between the graphene nanosheets, control of the intergraphene sheet distance through interacting molecules such as carbon nanotubes (CNT) or fullerenes (C60) might be crucial for enhancement of the storage capacity. The specific capacity of GNS was found to be 540 mAh/g, which is much larger than that of graphite, and this was increased up to 730 mAh/g and 784 mAh/g, respectively, by the incorporation of macromolecules of CNT and C60 to the GNS.     

Rational design of thermally stable polymorphic layered cathode materials for next generation lithium rechargeable batteries

Classical layered transition metal oxides have remained the preferred cathode materials for commercial lithium-ion batteries. Variation in the transition metal composition and local ordering can greatly affect the structure stability. In classical layered cathodes, high concentrations of electrochemically inert Mn elements usually act as a pillar to stabilize the structure. When excess amount of Li and Mn are present in the layered structure, the capacity of the Li-rich layered oxide (molar ratio of lithium over transition metal is larger than one by design) can exceed that expected from transition metal redox. However, the over lithiation in the classical layered structure results in safety issues, which remains challenging for the commercialization of Li-rich layered oxides. To characterize the safety performance of a series of Li-rich layered cathodes, we utilize differential scanning calorimeter and thermal gravimetric analysis; this is coupled with local structural changes using in situ temperature dependent synchrotron X-ray diffraction and X-ray adsorption spectroscopy. These methods demonstrate that the gradual decrease of the Mn–M (M = Ni, Co, Mn and Li) coordination number directly reduces structural stability and accelerates oxygen release. For safety characterization tests in practice, we evaluate the thermal runaway process through accelerating rate calorimeter in 1.0 Ah pouch cells to confirm this trend. Using the insights obtained in this work, we design a polymorphic composition to improve the thermal stability of Li-rich layered cathode material, which outperforms Ni-rich layered oxides in terms of both electrochemical and safety performances.     

Electrochemical performance and ex situ analysis of ZnMn2O4 nanowires as anode materials for lithium rechargeable batteries

One-dimensional ZnMn₂O₄ nanowires have been prepared and investigated as anode materials in Li rechargeable batteries. The highly crystalline ZnMn₂O₄ nanowires about 15 nm in width and 500 nm in length showed a high specific capacity of about 650 mAh·g⁻¹ at a current rate of 100 mA·g⁻¹ after 40 cycles. They also exhibited high power capability at elevated current rates, i.e., 450 and 350 mAh·g⁻¹ at current rates of 500 and 1000 mA·g⁻¹, respectively. Formation of Mn₃O₄ and ZnO phases was identified by ex situ X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies after the initial discharge-charge cycle, which indicates that the ZnMn₂O₄ phase was converted to a nanocomposite of Mn₃O₄ and ZnO phases immediately after the electrochemical conversion reaction.     

Polydiphenylamine/carbon nanotube composites for applications in rechargeable lithium batteries

Polydiphenylamine/single walled carbon nanotube (PDPA/SWNT) composites were synthesized electrochemically aiming at their application as active electrode materials for rechargeable lithium batteries. The electrochemical polymerization of diphenylamine (DPA) on a SWNT film immersed in a 1 M HCl solution was studied by cyclic voltammetry. Comparing cyclic voltammograms recorded on a blank Pt electrode with those obtained for a SWNT film deposited on Pt electrode one observes in the latter case a decrease of the DPA reduction potential. To elucidate electrochemical polymerization mechanism, photoluminescence studies on DPA/SWNT and PDPA/SWNT systems were carried out. Additional information concerning the functionalization process of SWNT with PDPA was obtained by Raman and IR spectroscopy. Using the PDPA/SWNT composite as active material for the positive electrode of a rechargeable lithium cell (LiPF₆ electrolyte), the charge-discharge tests show a specific discharge capacity of ca. 245 mA h g⁻¹, much higher than the 35 mA h g⁻¹ for pure PDPA.     

MXenes and their derivatives for advanced aqueous rechargeable batteries

Aqueous batteries are emerging power sources due to the merits of high safety, low cost, environmental friendliness, etc. However, several key issues such as narrow electrochemical stability window, dissolution of active materials, notorious dendrite growth and poor cycling lifespan hinder the practical application of aqueous batteries. Recently, 2D MXenes and their derivatives for aqueous batteries have exhibited substantial encouraging progress due to the special characters. The related researches have dramatically increased since 2019. However, comprehensive reviews on this topic are rare. Herein, the latest advances of MXenes and their derivatives for aqueous Zn-, Li-, Na- and dual-ion batteries are systematically reviewed, including cathode fabrication, anode design and electrolyte optimization, etc. This review aims to boost rational design strategies for practical application of aqueous batteries by combining the fundamental principle and research developments. Firstly, the fundamental background of aqueous rechargeable batteries is introduced and the superior merits for electrochemical energy storage of MXenes and their derivatives are summarized. Subsequently, the design strategies and internal mechanism of MXenes and their derivatives for aqueous batteries are comprehensively summarized and discussed. Finally, perspectives on the future design tactics of MXenes-based materials for aqueous batteries are proposed.