Yanna Nuli

Multilayered Cobalt Oxide Platelets for Negative Electrode Material of a Lithium-Ion Battery

Layer-controllable CoO and Co(3)O(4) platelets were prepared by calcination of hexagonal beta-Co(OH)(2), which was synthesized via a surfactant-free hydrothermal method. As negative electrode material for lithium-ion batteries, CoO and Co(3)O(4) platelets demonstrated high reversible capacity (more than 800 mAh/g for CoO and 600 mAh/g for Co(3)O(4)) and excellent electrochemical cycling stability. The multilayered CoO platelets showed larger capacity and much better cycling performance than the monolayer CoO platelets and CoO nanoparticles. The effect of dimension and morphology of CoO particles on the electrode behavior was discussed. (c) 2008 The Electrochemical Society. [DOI:10.1149/1.2987945] All rights reserved.

A novel pyrolyzed polyacrylonitrile-sulfur@MWCNT composite cathode material for high-rate rechargeable lithium/sulfur batteries

A novel pPAN-S@MWCNT core-shell composite material is prepared via in situpolymerization of acrylonitrile on the surface of MWCNT, mixing with sulfur and final pyrolysis. The homogenous dispersion and integration of MWCNT in the composite create an electronically conductive network and reinforce the structural stability, leading to the outstanding electrochemical performances as a cathode material for rechargeable lithium/sulfur batteries.

Microporous carbon coated silicon core/shell nanocomposite via in situ polymerization for advanced Li-ion battery anode material.

A microporous carbon coated core/shell Si@C nanocomposite prepared by in situ polymerization exhibits a stable capacity of over 1200 mAh g(-1) with 95.6% retention even after 40 cycles, which makes it a promising anode material for lithium ion batteries.

Ultra-fine porous SnO2 nanopowder prepared via a molten salt process: a highly efficient anode material for lithium-ion batteries

Ultra-fine porous SnO2nanoparticles for lithium ion batteries were prepared by a simple, easily scaled-up molten salt method at 300 °C. The structure and morphology were confirmed by X-ray diffraction and transmission electron microscopy. The as-prepared SnO2 had a tetragonal rutile structure with crystal sizes around 5 nm. The electrochemical performance was tested compared with commercial nanopowder and previously reported nanowires. The as-prepared nanoparticles delivered a significantly higher discharge capacity and better cycle retention. The nanoparticle electrode delivered a reversible capacity of 410 mAh g−1 after 100 cycles. Even at high rates, the electrode operated at a good fraction of its capacity. The excellent electrochemical performance of the ultra-fine porous SnO2 can be attributed to the ultra-fine crystallites (which tend to decrease the absolute volume changes) and the porous structure (which promotes liquid electrolyte diffusion into the bulk materials and acts as a buffer zone to absorb the volume changes).

Boron-based electrolyte solutions with wide electrochemical windows for rechargeable magnesium batteries

Recently, we have developed a boron based electrolyte system with outstanding electrochemical performance, formed through the reaction of tri(3,5-dimethylphenyl)borane (Mes3B) and PhMgCl in THF, for rechargeable magnesium batteries. In this paper, the main components and equilibria of the unique boron based electrolyte solutions are identified by NMR, single-crystal XRD, etc. The results prove that the solutions contain various magnesium species, such as Mg2Cl3+, MgCl+, Ph2Mg and the tetracoordinated boron anion [Mes3BPh]−. Fluorescence spectra and Raman spectroscopy analyses indicate that the high anodic stability (ca. 3.5 V vs. Mg reference electrode (RE)) of the Mes3B–(PhMgCl)2 electrolyte is attributed to the non-covalent interactions between the anion [Mes3BPh]− and Ph2Mg. Furthermore, the air sensitivity of the boron based electrolyte and its electrochemical stability on the different current collectors are studied. Finally, the reversible electrochemical process of Mg intercalation into a Mo6S8 cathode confirms that the boron based electrolyte could be practically used in rechargeable Mg battery systems.

NiCo2O4 / C Nanocomposite as a Highly Reversible Anode Material for Lithium-Ion Batteries

A NiCo 2 O 4 /C nanocomposite has been synthesized by a hydrothermal method followed by a calcination. X-ray powder diffraction and transmission electron microscopy measurements demonstrated the composite was composed of crystalline NiCo 2 O 4 and amorphous carbon, and NiCo 2 O 4 and carbon particles amalgamated together with good affinity. The electrochemical results showed as high as 914.5 mAh/g reversible capacity could be achieved at 40 mA/g current density in the potential range of 0.01-3.0 V. The initial coulombic efficiency of the composite was 79.2%, and the capacity retention was 78.3% up to 50 cycles. The superior electrochemical performance indicated that the NiCo 2 O 4 /C nanocomposite might be a promising alternative to conventional graphite-based anode materials for lithium-ion batteries.

Shape Evolution of α-Fe2O3 and Its Size-Dependent Electrochemical Properties for Lithium-Ion Batteries

Crystalline α-Fe 2 O 3 with different particle shapes and sizes was selectively synthesized by a simple hydrothermal method. By carefully tuning the concentration of the reactants and the reaction time, α-Fe 2 O 3 cuboid particles and nanowires can be obtained. Based on the evidence of electron microscope images, a shape evolution mechanism for the nanowire structure is proposed. Electrochemical performance as an anode material for lithium-ion batteries was further evaluated by cyclic voltammetry, electrochemical impedance, and charge-discharge measurements. It was demonstrated that both the morphology and the particle size had an influence on the performance. Compared with the electrode made from the cuboid material, the nanowire electrode displayed higher discharge capacity and better cycling reversibility, which may be a result of the one-dimensional nanostructure and high surface area.

Towards a Safe Lithium–Sulfur Battery with a Flame‐Inhibiting Electrolyte and a Sulfur‐Based Composite Cathode

Of the various beyond-lithium-ion batteries, lithium-sulfur (Li-S) batteries were recently reported as possibly being the closest to market. However, its theoretically high energy density makes it potentially hazardous under conditions of abuse. Therefore, addressing the safety issues of Li-S cells is necessary before they can be used in practical applications. Here, we report a concept to build a safe and highly efficient Li-S battery with a flame-inhibiting electrolyte and a sulfur-based composite cathode. The flame retardant not only makes the carbonates nonflammable but also dramatically enhances the electrochemical performance of the sulfur-based composite cathode, without an apparent capacity decline over 750 cycles, and with a capacity greater than 800 mA h(-1)  g(-1) (sulfur) at a rate of 10 C.

Graphene oxide doped conducting polymer nanocomposite film for electrode-tissue interface

One of the most significant components for implantable bioelectronic devices is the interface between the microelectrodes and the tissue or cells for disease diagnosis or treatment. To make the devices work efficiently and safely in vivo, the electrode-tissue interface should not only be confined in micro scale, but also possesses excellent electrochemical characteristic, stability and biocompatibility. Considering the enhancement of many composite materials by combining graphene oxide (GO) for its multiple advantages, we dope graphene oxide into poly(3,4-ethylenedioxythiophene) (PEDOT) forming a composite film by electrochemical deposition for electrode site modification. As a consequence, not only the enlargement of efficient surface area, but also the development of impedance, charge storage capacity and charge injection limit contribute to the excellent electrochemical performance. Furthermore, the stability and biocompatibility are confirmed by numerously repeated usage test and cell proliferation and attachment examination, respectively. As electrode-tissue interface, this biomaterial opens a new gate for tissue engineering and implantable electrophysiological devices.

A new ether-based electrolyte for dendrite-free lithium-metal based rechargeable batteries.

A new ether-based electrolyte to match lithium metal electrode is prepared by introducing 1, 4-dioxane as co-solvent into lithium bis(fluorosulfonyl)imide/1,2-dimethoxyethane solution. Under the synergetic effect of solvents and salt, this simple liquid electrolyte presents stable Li cycling with dendrite-free Li deposition even at relatively high current rate, high coulombic efficiency of ca. 98%, and good anodic stability up to ~4.87 V vs Li RE. Its excellent performance will open up a new possibility for high energy-density rechargeable Li metal battery system.