Metallic mono-layered C4N as a potential anode material for Na-ion batteries: A first-principles investigation

First-principles calculations based on density functional theory were used to study the adsorption behaviors of Na on metallic mono-layered C₄N as electrode materials for Na-ion batteries. The adsorption energy of Na atom was calculated to be 2.05 eV, which is much higher than Na bulk cohesive energy and sufficiently ensure stability and safety. It is worth noting that the Dirac-type band structure of mono-layered C₄N has a ultrahigh capacity of 1945.89 mAh/g for Na-ion batteries anode in theory. Remarkably, 2D C₄N has a low diffusion barrier 0.071 and 0.075 eV for path I and path II, respectively. The average open circuit voltage is 1.383 eV when nine Na ions adsorbed on one side of mono-layered C₄N. All the excellent properties show that the mono-layered C₄N will be a potential development of anode materials for Na-ion batteries.     

在充放电循环过程中Ni/MH电池正负极的结构和性能变化

本文对在连续进行充放电循环过程中Ni/MH电池的放电容量、中值电压与循环周期的关系以及电池正负极结构和性能的变化进行了研究。结果表明：电池在循环过程中正极活性物质基本构型未变化，而负极储氢合金表面逐渐生成了La(OH)₃、Al(OH)₃、LiMnO₂，正负极活性物质随循环次数的增加不断发生粉化，这些都是导致Ni/MH电池放电性能下降的主要因素。     

Stand und Entwicklungstendenzen auf Dem Gebiet Der Straiilenteciinik und -Technologie Isotopenbatterien

Mit der Abtrennung von Radionukliden aus Wiederaufbereitungslösungen in größerem Maßstab und der Entwicklung der Mikroeleklronik ergeben sich neue Gesichtspunkte für den Einsatz von Isotopenbatterien. Es wird eine, Übersicht über die Entwicklung solcher Energiequellen gegeben. Nach der Beschreibung der wichtigsten Konversionsprinzipien wird der erreichte Entwicklungsstand eingeschätzt. Abschließend wird auf wahrscheinliche Entwicklungsrichtungen hingewiesen.     

The Use of an Emulsion Templated Microcellular Poly(dicyclopentadiene‐co‐norbornene) Membrane as a Separator in Lithium‐Ion Batteries

The preparation of open‐cell macroporous membranes made by the ring opening metathesis polymerization (ROMP) of a mixture of norbornene and dicyclopentadiene, and their basic applicability as separators in lithium‐ion batteries, is discussed. Cyclic voltammetry (CV) measurements of negative electrodes (graphite) and positive electrodes (LiCoO₂) are performed and the results prove the absence of parasitic decomposition reactions within the membrane at high oxidative or reductive potentials. Furthermore, LiCoO₂/Li half cell cycling studies of 100 charging/discharging cycles reveal that the newly disclosed separator and conventional commercial polyolefin based separators have similar performance. These results demonstrate that a potential weakness in the newly disclosed separator, namely residual double bonds present in the polymer network, does not limit the use of this material as a separator in lithium‐ion batteries.

     

Multilevel Coupled Hybrids Made of Porous Cobalt Oxides and Graphene for High-Performance Lithium Storage

Metal oxide coupling with carbon materials holds great promise for lithium storage. Herein, multilevel coupled cobalt oxide–graphene (CoO/CO₃O₄–G) hybrids were fabricated by in situ assembly of Co hydroxide precursors and a calcination process. The oxygen-containing functional groups on the graphene surface act as bridging sites and tend to bond with Co²⁺ ions, effectively modifying the morphology and structure of the Co species. The as-obtained CoO/CO₃O₄–G hybrids are composed of unique CoO/CO₃O₄ porous nanoparticles uniformly anchored on graphene sheets, as confirmed by a series of characterization analyses. Benefiting from these structural characteristics, the CoO/CO₃O₄–G hybrids used as an anode can deliver a high capacity of about 1080 mA h g⁻¹ reversibly at 0.1 Ag⁻¹ in the voltage range between 3.0 and 0.01 V, which is remarkably superior to that of the CoO hexagonal sheets in the absence of graphene. The high reversible capacity of the CoO/CO₃O₄–G hybrids is retained at elevated current densities, for example, a capacity of approximately 455 mA h g⁻¹ can be achieved at a current rate as high as 4 A g⁻¹, indicative of its potential for high-performance lithium-ion batteries.     

Synthesis,Structure and Electrochemical Lithium Intercalation Chemistry of Ramsdellite‐Type LiCrTiO4

LiCrTiO₄, which crystallizes in the orthorhombic ramsdellite structure, has been obtained by heating spinel LiCrTiO₄ at 1250 °C in air. The refined cell parameters are a = 4.9835(6) Å, b = 9.5095(8) Å and c = 2.9282(2) Å, space group Pbnm, as determined from Rietveld refinement of X‐ray powder diffraction data. The intercalation chemistry of LiCrTiO₄ has been investigated. Lithium can be extracted from LiCrTiO₄ due to oxidation of Cr^III at rather high potential 4 V. On the other hand, lithium intercalation proceeds readily at 1.5 V due to the reduction of tetravalent titanium. Regarding practical applications, as an electrode for lithium rechargeable batteries, specific capacities of 100 and 120 mAh·g^?1 are developed at 0.1 mA·cm^?2, respectively. These findings point out that the ramsdellite form of LiCrTiO₄ may be an ambivalent electrode, which can be used either as the positive electrode or the negative electrode of a lithium ion rechargeable battery.     

Synthesis by arc-discharge method and electrochemical lithium insertion properties of double-walled carbon nanotubes

Double-walled carbon nanotubes could be synthesized by arc-discharge method using ball-milling mixtures of iron, cobalt, nickel and sulfide as catalysts. Structures of these carbon nanotubes were characterized by TEM, HRTEM and Raman spectroscopy. Also the lithium insertion properties were examined. The results showed that the irreversible capacity of the double-walled carbon nanotube lithium ion batteries is high, which is considered to be related to the formation of SEI on the surface of the electrodes in the process of electrochemistry reaction. Published in Russian in Elektrokhimiya, 2008, vol. 44, No. 11, pp. 1333–1336. The text was submitted by the authors in English.     

Recent advances in conjugated polymer energy storage

This review covers recent advances in conjugated polymers and their application in energy storage. Conjugated polymers are promising cost-effective, lightweight, and flexible electrode materials. The operating principles of conjugated polymers are presented within the framework of their potential for energy storage. Special focus is given to polyaniline electrodes. Recent advances are reviewed including new methods of synthesis, nanostructuring, and assembly. Also, covered are applications that take full advantage of the mechanical properties of conjugated polymers and future applications of these novel materials. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013     

A redox‐active polythiophene‐modified separator for safety control of lithium‐ion batteries

A potential‐sensitive separator is prepared simply by incorporating a redox‐active poly(3‐butylthiophene) (P3BT) into the micropores of a commercial porous polyolefin film and tested for overcharge protection of LiFePO₄/Li₄Ti₅O₁₂ lithium‐ion batteries. The experimental results demonstrate that owing to the reversible p‐doping and dedoping of the redox‐active P3BT polymer embedded in the separator with the changes of the cathode potential from an overcharge state to a normal operating state, this type of separator can reversibly switch between electronically insulating state and conductive state to maintain the charge voltage of LiFePO₄/Li₄Ti₅O₁₂ cells at a safety value of ≤2.4 V, and thus protecting the cell from voltage runaway. As this type of the separators works reversibly and has no negative impact on the battery performances, it can be used as an internal and self‐protecting mechanism for commercial lithium‐ion batteries and other rechargeable batteries. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1487–1493