Tin/polypyrrole composite anode using sodium carboxymethyl cellulose binder for lithium-ion batteries
ABSTRACT A tin nanoparticle/polypyrrole (nano-Sn/PPy) composite was prepared by chemically reducing and coating Sn nanoparticles onto the PPy surface. The composite shows a much higher surface area than the pure nano-Sn reference sample, due to the porous higher surface area of PPy and the much smaller size of Sn in the nano-Sn/PPy composite than in the pure tin nanoparticle sample. Poly(vinylidene fluoride) (PVDF) and sodium carboxymethyl cellulose (CMC) were also used as binders, and the electrochemical performance was investigated. The electrochemical results show that both the capacity retention and the rate capability are in the same order of nano-Sn/PPy-CMC > nano-Sn/PPy-PVDF > nano-Sn-CMC > nano-Sn-PVDF. Scanning electronic microscopy (SEM) and electrochemical impedance spectroscopy (EIS) results show that CMC can prevent the formation of cracks in electrodes caused by the big volume changes during the charge-discharge process, and the PPy in the composite can provide a conducting matrix and alleviate the agglomeration of Sn nanoparticles. The present results indicate that the nano-Sn/PPy composite could be suitable for the next generation of anode materials with relatively good capacity retention and rate capability.
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ABSTRACT: Organic electrode materials have long been proposed but their electrochemical performances are far from satisfactory in, for example, specific capacity and cycling stability, for secondary batteries. This article reports the electrochemical performance of a composite of polypyrrole (PPy) and nickel oxide (NiO), in which another lithium storage material, polypyrrole–nickel–oxygen (PPy–Ni–O) coordination complex, was fabricated during initial galvanostatically discharging. Extended X-ray absorption fine structure (EXAFS) spectroscopy and density functional theory (DFT) calculations indicate the process of the electrochemical formation of a PPy–Ni–O coordination and determine its multilayer structure. The strong and electrochemically stable coordination between the nickel and nitrogen atoms ensures the excellent electrochemical performances of the complex. These findings pave new ways to construct a new type of high-performance organic anode material for lithium ion batteries.Electrochimica Acta 08/2013; 105:162–169. DOI:10.1016/j.electacta.2013.04.086 · 4.09 Impact Factor
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ABSTRACT: During the past decade humans have witnessed dramatic expansion of fundamental research as well as the commercialization in the area of electrochemical energy storage, which is driven by the urgent demand by portable electronic devices, electric vehicles, transportation and storage of renewable energy for the power grid in the clean energy economy. Li-secondary batteries and electrochemical capacitors can efficiently convert stored chemical energy into electrical energy, and are currently the rapid-growing rechargeable devices. However, the characteristic (including energy density, cost, and safety issues, etc.) reported for these current rechargeable devices still cannot meet the requirements for electric vehicles and grid energy storage, which are mainly caused by the limited properties of the key materials (e.g. anode, cathode, electrolyte, separator, and binder) employed by these devices. Moreover, these key materials are normally far from renewable and sustainable. Therefore great challenges and opportunities remain to be realized are to search green and low-cost materials with high performances. A large number of the properties of biomass materials-such as renewable, low-cost, earth-abundant, specific structures, mechanical property and many others-are very attractive. These properties endow that biomass could replace some key materials in electrochemical energy storage systems. In this review, we focus on the fundamentals and applications of biomass-derived materials in electrochemical energy storage techniques. Specifically, we summarize the recent advances of the utilization of various biomasses as separators, binders and electrode materials. Finally, several perspectives related to the biomass-derived materials for electrochemical energy storages are proposed based on the reported progress and our own evaluation, aiming to provides some possible research directions in this field.Progress in Polymer Science 10/2014; 43. DOI:10.1016/j.progpolymsci.2014.09.003 · 26.85 Impact Factor
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ABSTRACT: Polypyrrole nanowires are successfully fabricated with a one-step process by cathodic electropolymerization from an aqueous solution without templates and chemical additives. The method utilizes electrochemically generated NO+ to oxidize the neutral pyrrole monomers, making it possible to use oxidizable metal substrates, such as Cu and Ni. The synthesized nanowires are directly deposited on the substrate in the form of a thin film consisting of fine polypyrrole nanowires with a nanoporous and interconnected network structure. The growth kinetics of the polypyrrole nanowires was investigated by analyzing the effects of the chemical composition of the electrolyte and the synthesis time on the formation of polypyrrole nanowires. It was found that the polymerization process of pyrrole is very sensitive to the reactivity of radical cations. For a radical cation with high reactivity, the polypyrrole nanospheres are synthesized near the electrode in the solution. In contrast, for a radical cation with sufficiently low reactivity, the polypyrrole nanowires are grown on the priorly deposited polypyrrole nanospheres.06/2013; 1(27):8061-8068. DOI:10.1039/C3TA11227F