Nerino Penazzi

Aqueous processing of cellulose based paper-anodes for flexible Li-ion batteries

Cellulose fibers were used as novel bio-sourced binder to manufacture flexible cellulose/graphite paper-anodes for Li-ion batteries by means of a simple water-based filtration process easily up-scalable capitalizing conventional papermaking technologies. Paper-anodes showed excellent tensile properties with Young moduli ranging between 60 and 450 MPa, discharge capacity values up to 300/350 mA h g-1 and cycling performances comparable with conventional polymer-bonded graphite anodes.

Flexible cellulose/LiFePO4 paper-cathodes: toward eco-friendly all-paper Li-ion batteries

Today most of commercial Li-ion batteries (LIBs) are manufactured using toxic solvents and synthetic polymer binders. In order to lower the cost and the environmental impact of LIBs an effort must be made to identify low-cost and environmentally friendly materials and processes. In this work, flexible, self-standing and easily recyclable LiFePO4 cathodes are obtained using cellulose fibers as biosourced binder and a quick, aqueous filtration process, easily upscalable capitalizing the well-established papermaking know-how. The obtained paper-cathodes show very good mechanical properties, with Young’s modulus as high as 100 MPa, discharge capacity values up to 110 mAh g−1 and very good cycling performances, comparable with conventional polymer-bonded LiFePO4 cathodes. Moreover, a complete paper-cell, constituted by a paper-cathode, a paper-separator and a paper-anode is presented, showing good cycling performances in terms of specific capacity, efficiency and stability.

Effect of some elements on oxygen reduction and hydrogen evolution at lead-acid battery negative plates

Abstract The effects which the impurities As, Bi, Cd, Co, Cr, Ni, Sb, Se, Sn and Te have on the processes of hydrogen evolution and oxygen reduction on the negative plates of lead-acid batteries have been tested. This was done by measuring the gas pressure in sealed vessels containing cycled, wet, negative plates. The addition of As, Co, Ni, Sb and Te to the electrolyte used during the cycling increases the hydrogen ion discharge rate, whereas Cr, Bi and Sn have the opposite effect. In the case of oxygen, As, Bi, Ni, Sb, Se, Sn, and Te promote its reduction while Co and Cr suppress it. The effect of impurity concentration has also been considered.

Effect of nickel impurities on zinc electrodeposition

The kinetics of nickel-zinc co-deposition and the effect of nickel on zinc morphology have been studied by means of chemical analysis, X-ray diffraction and SEM observations of cathodic deposits obtained in various experimental conditions, including acid and alkaline baths. It has been shown that nickel ions, even if present in the electrolyte at very low concentrations (1 ppm), do not deposit under mass transport controlled conditions but are dragged by zinc ions whose concentration influences the nickel current. With regard to zinc morphology, it has been observed that nickel reduces the grain size of the zinc crystals formed during the electrodeposition.

Mixed lithium phosphates as cathode materials for Li-Ion cells

Abstract LiFe x Co (1– x ) PO 4 ( x =0.2, 0.5, 0.8,1) solid solutions have been prepared by solid state reaction method to sevatudy the electrochemical performance of these olivine structure compounds as cathode material for lithium-ion batteries. SEM observations, X-ray powder diffraction (XRPD) profiles and Rietveld refinement have been carried out to investigate the structural characteristics and morphology of the samples. During the preparations citric acid was added to the reactants to improve the electronic conductivity of the cathode. The results showed that when present in small amounts, Co exerts a beneficial effect mainly at the first cycles where the additive is not effective. At higher Co levels this positive effect seems to cease, probably is still present but hidden by the progressive electrolyte degradation that causes a decay of the electrochemical performance.

Synthesis and characterization of LiCoyNi(1-y)VO4 lithium insertion materials

Abstract A family of mixed LiCo y Ni (1− y ) VO 4 ( y =0.2, 0.5 and 0.8) compounds of potential use as high voltage cathode materials in lithium batteries, has been synthesized and characterized. The X-ray diffraction analysis showed that these compounds adopt an inverse spinel structure where in average 85% of the Ni 2+ and Co 2+ ions occupy octahedral sites and the other 15% occupy tetrahedral sites with the V 5+ ions, although this occupation share is somewhat influenced by the preparation temperature. The annealing temperature plays also a key role in determining the particle size, as demonstrated by scanning electron microscope analysis. Cycling voltammetry tests showed that the lithium insertion–deinsertion process in the LiCo y Ni (1− y ) VO 4 electrode materials occurs reversibly around 4.3–4.4 V vs. Li, as also confirmed by cycling tests. The cycling capacity is somewhat modest; however, the trend of the cycling curves leads to foresee that a consistent increase in capacity may be obtained by extending the charging process beyond 4.6 V vs. Li, once a stable electrolyte will be available.

Zinc corrosion in NH4Cl and effect of some organic inhibitors

Abstract The corrosion of zinc in ammonium chloride, both pure and containing various organic compounds, has been studied by means of analytical and electrochemical methods as the determination of the zinc dissolved and the hydrogen evolved, I ( V ) curge recording and impedance measurements. The results obtained in a potential region near the zinc corrosion potential showed that the cathodic reaction of hydrogen discharge does not fit a simple exponential law because the Tafel coefficient appears to be electrode potential dependent. The experimental findings proved that only five of the 25 organic substances tested have been found to behave as zinc corrosion inhibitors (NDA, POELE, FORAFAC, TTH and TRITON in decreasing order of influence).

Sealed gas recombining lead—acid batteries part i. a simple theoretical approach

Abstract The solution of the differential equations expressing the gas material balance in a sealed lead—acid cell led us to propose a simple experimental method to evaluate the parameters controlling the cell behaviour both in dynamic and in steady state conditions.

MgB2 thin films on silicon nitride substrates prepared by an in situ method

Large-area MgB2 thin films were deposited on silicon nitride and sapphire substrates by co-deposition of Mg and B. After a post-annealing in Ar atmosphere at temperatures between 773 and 1173?K depending on the substrate, the films showed a critical temperature higher than 35?K with a transition width less than 0.5?K. The x-ray diffraction pattern suggested a c-axis preferential orientation in films deposited on amorphous substrate. The smooth surface and the good structural properties of these MgB2 films allowed their reproducible patterning by a standard photolithographic process down to dimensions of the order of 10??m and without a considerable degradation of the superconducting properties.

Effects of antimony on the electrochemical behaviour of lead dioxide in sulphuric acid

Abstract The effect of antimony on the reduction of the two allotropic forms of lead dioxide in sulphuric acid electrolyte has been studied. The effects of antimony doping of the lead dioxide lattice and the effects of antimony contamination of the electrolyte have been considered separately. In the first case antimony increases the quantity of charge related to the reduction, and in the second it exerts a strong passivating influence on the lead dioxide electrodes.