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Cycling Performance (cycling + performance)

Distribution by Scientific Domains

Polymers and Materials Science	60%

Selected Abstracts

Synthesis and Lithium Storage Properties of Co3O4 Nanosheet-Assembled Multishelled Hollow Spheres

ADVANCED FUNCTIONAL MATERIALS, Issue 10 2010
Xi Wang
Abstract Single-, double-, and triple-shelled hollow spheres assembled by Co3O4 nanosheets are successfully synthesized through a novel method. The possible formation mechanism of these novel structures was investigated using powder X-ray diffraction, scanning and transmission electron microscopies, Fourier transform IR, X-ray photoelectron spectroscopy, and thermogravimetric analysis. Both poly(vinylpyrrolidone) (PVP) soft templates and the formation of cobalt glycolate play key roles in the formation of these novel multishelled hollow structures. When tested as the anode material in lithium-ion batteries (LIBs), these multishelled microspheres exhibit excellent cycling performance, good rate capacity, and enhanced lithium storage capacity. This superior cyclic stability and capacity result from the synergetic effect of small diffusion lengths in the nanosheet building blocks and sufficient void space to buffer the volume expansion. This facile strategy may be extended to synthesize other transition metal oxide materials with hollow multishelled micro-/nanostrucutures, which may find application in sensors and catalysts due to their unique structural features. [source]

Research on Advanced Materials for Li-ion Batteries

ADVANCED MATERIALS, Issue 45 2009
Hong Li
Abstract In order to address power and energy demands of mobile electronics and electric cars, Li-ion technology is urgently being optimized by using alternative materials. This article presents a review of our recent progress dedicated to the anode and cathode materials that have the potential to fulfil the crucial factors of cost, safety, lifetime, durability, power density, and energy density. Nanostructured inorganic compounds have been extensively investigated. Size effects revealed in the storage of lithium through micropores (hard carbon spheres), alloys (Si, SnSb), and conversion reactions (Cr2O3, MnO) are studied. The formation of nano/micro core,shell, dispersed composite, and surface pinning structures can improve their cycling performance. Surface coating on LiCoO2 and LiMn2O4 was found to be an effective way to enhance their thermal and chemical stability and the mechanisms are discussed. Theoretical simulations and experiments on LiFePO4 reveal that alkali metal ions and nitrogen doping into the LiFePO4 lattice are possible approaches to increase its electronic conductivity and does not block transport of lithium ion along the 1D channel. [source]

Designed Synthesis of Coaxial SnO2@carbon Hollow Nanospheres for Highly Reversible Lithium Storage

ADVANCED MATERIALS, Issue 24 2009
Xiong Wen Lou
A proof-of-concept structural design is demonstrated for high-capacity lithium-ion batteries anode materials by multistep synthesis of coaxial SnO2@carbon hollow nanospheres. This material integrates two beneficial features: hollow structure and carbon nanopainting. When evaluated for reversible lithium storage, these functional materials manifest excellent cycling performance and rate capabilities. [source]

The Effect of Using Variable Frequency Trains During Functional Electrical Stimulation Cycling

NEUROMODULATION, Issue 3 2008
Simona Ferrante PhD
ABSTRACT Objectives., This paper describes an experimental investigation of variable frequency stimulation patterns as a means of increasing torque production and, hence, performance in cycling induced by functional electrical stimulation. Materials and Methods., Experiments were conducted on six able-bodied subjects stimulating both quadriceps during isokinetic trials. Constant-frequency trains (CFT) with 50-msec interpulse intervals and four catchlike-inducing trains (CIT) were tested. The CITs had an initial, brief, high-frequency burst of two pulses at the onset of or within a subtetanic low-frequency stimulation train. Each stimulation train consisted of the same number of pulses. The active torques produced by each train were compared. Parametric main effect ANOVA tests were performed on the active torque-time integral (TTI), on the active torque peaks and on the time needed to reach those peaks (T2P). Results., The electrical stimulation of the quadriceps produced active torques with mean peak values in the range of 1.6,3.5 Nm and a standard error below 0.2 Nm. CITs produced a significant increase of TTI and torque peaks compared with CFTs in all the experimental conditions. In particular, during the postfatigue trials, the CITs with the doublet placed in the middle of the train produced TTIs and torque peaks about 61% and 28% larger than the CFT pattern, respectively. In addition, the CITs showed the lowest reduction of the performance between prefatigue and postfatigue conditions. Conclusions., The use of CITs improves the functional electrical stimulation cycling performance compared with CFT stimulation. This application might have a relevant clinical importance for individuals with stroke where the residual sensation is still present and thus the maximization of the performance without an excessive increase of the stimulation intensity is advisable. Therefore, exercise intensity can be increased yielding a better muscle strength and endurance that may be beneficially for later gait training in individuals with stroke. [source]

In-Situ Encapsulation of Nickel Particles in Electrospun Carbon Nanofibers and the Resultant Electrochemical Performance

CHEMISTRY - A EUROPEAN JOURNAL, Issue 41 2009
Liwen Ji
Loaded nanofibers: Ni nanoparticle-loaded carbon nanofibers, which exhibit high reversible lithium-storage capacity, excellent cycling performance, and remarkably enhanced rate capability, are fabricated by using the electrospinning technique and the subsequent stabilization and carbonization processes (see figure). [source]