Analysis of impedance spectra taken at closely spaced bias potential values on LixNi0.75Co0.25O2 have been interpreted in terms of electronic and ionic transport properties of this electrode material. In the 0.9<x<1 range the... more
Analysis of impedance spectra taken at closely spaced bias potential values on LixNi0.75Co0.25O2 have been interpreted in terms of electronic and ionic transport properties of this electrode material. In the 0.9<x<1 range the material shows semi-conductive properties and the electronic conductivity dominates the transport. For x≤0.9, the properties change into those of a metal-like material in which the ionic conductivity becomes the limiting factor. The transition between these two limiting conditions clearly appears in the impedance spectra sequence. This transition is reversible since the same behaviour is observed during the lithium intercalation process as well as in the reverse lithium deintercalation process.
The reuse and recycling of products, leading to the utilization of wastes as key resources in a closed loop, is a great opportunity for the market in terms of added value and reduced environmental impact. In this context, producing... more
The reuse and recycling of products, leading to the utilization of wastes as key resources in a closed loop, is a great opportunity for the market in terms of added value and reduced environmental impact. In this context, producing carbonaceous anode materials starting from raw materials derived from food waste appears to be a possible approach to enhance the overall sustainability of the energy storage value chain, including Li-ion (LIBs) and Na-ion batteries (NIBs). In this framework, we show the behavior of anodes for LIBs and NIBs prepared with coffee ground-derived hard carbon as active material, combined with green binders such as Na-carboxymethyl cellulose (CMC), alginate (Alg), or polyacrylic acid (PAA). In order to evaluate the effect of the various binders on the charge/discharge performance, structural and electrochemical investigations are carried out. The electrochemical characterization reveals that the alginate-based anode, used for NIBs, delivers much enhanced charge...
Research Interests:
Research Interests:
All solid-state lithium batteries (ASLB) are paving the attention of the battery community due to the possibility of improving safety at good energy level. Their future development requires the investigation of new electrodes chemistries... more
All solid-state lithium batteries (ASLB) are paving the attention of the battery community due to the possibility of improving safety at good energy level. Their future development requires the investigation of new electrodes chemistries both based on intercalation or conversion mechanism. In this work we report on the synthesis and characterization of a V2O5 cryogel electrode and its application in ASLB. The combination of V2O5 cryogel and a solid-state electrolyte shows appealing properties of high capacity and enhanced safety. (C) 2019 The Electrochemical Society.
Research Interests:
A tin-decorated reduced graphene oxide, originally developed for lithium-ion batteries, has been investigated as an anode in sodium-ion batteries. The composite has been synthetized through microwave reduction of poly acrylic acid... more
A tin-decorated reduced graphene oxide, originally developed for lithium-ion batteries, has been investigated as an anode in sodium-ion batteries. The composite has been synthetized through microwave reduction of poly acrylic acid functionalized graphene oxide and a tin oxide organic precursor. The final product morphology reveals a composite in which Sn and SnO2 nanoparticles are homogenously distributed into the reduced graphene oxide matrix. The XRD confirms the initial simultaneous presence of Sn and SnO2 particles. SnRGO electrodes, prepared using Super-P carbon as conducting additive and Pattex PL50 as aqueous binder, were investigated in a sodium metal cell. The Sn-RGO showed a high irreversible first cycle capacity: only 52% of the first cycle discharge capacity was recovered in the following charge cycle. After three cycles, a stable SEI layer was developed and the cell began to work reversibly: the practical reversible capability of the material was 170 mA·h·g−1. Subsequen...
Research Interests:
Fe3O4 nanoparticles synthesized by a base catalyzed method are tested in an All-Solid-State (ASLB) battery using a sulfide electrolyte. The pristine nanoparticles were morphologically characterized showing an average size of 12 nm. The... more
Fe3O4 nanoparticles synthesized by a base catalyzed method are tested in an All-Solid-State (ASLB) battery using a sulfide electrolyte. The pristine nanoparticles were morphologically characterized showing an average size of 12 nm. The evaluation of the electrochemical properties shows high specific capacity values of 506 mAhg−1 after 350 cycles at a specific current of 250 mAg−1 , with very high stability and coulombic efficiency.
Research Interests:
Research Interests:
Conversion‐enabled transition metal oxides are mostly characterized by environmental benignity, low cost, and high theoretical capacities, which make them suitable as candidate anode materials for Li‐ion batteries. To ensure high... more
Conversion‐enabled transition metal oxides are mostly characterized by environmental benignity, low cost, and high theoretical capacities, which make them suitable as candidate anode materials for Li‐ion batteries. To ensure high efficiency and stability, the use of novel and tailored morphologies is recommended. Among the other methods, the use of natural extracts as templates is one of the possible strategies to accomplish this task. In this work, Fe2O3 nanoparticles are synthesized by using vanillin as a soft templating agent, and fully characterized on a morphological, structural and electrochemical level. Poly(acrylic acid) binder and ethanol for electrode preparation ensure a fully environmentally benign process from synthesis to electrode testing. The cells deliver capacity values up to 700 mAh g−1 under prolonged galvanostatic cycling at 500 mA g−1, as well as excellent rate capability and high efficiency.
Research Interests:
Fe 3 O 4 nanoparticles were synthesized using a modified base-catalyzed method. Polyacrylic Acid was used as alternative binder. High capacities were evidenced for over 100 cycles at 462 mAg À1 specific current. Gel-type interface was... more
Fe 3 O 4 nanoparticles were synthesized using a modified base-catalyzed method. Polyacrylic Acid was used as alternative binder. High capacities were evidenced for over 100 cycles at 462 mAg À1 specific current. Gel-type interface was evidenced by FTIR and Impedance spectroscopy. a b s t r a c t Fe 3 O 4 nanoparticles synthesized by a base catalyzed method are tested as anode material for Li-ion batteries. The pristine nanoparticles are morphologically characterized showing an average size of 11 nm. Electrodes are prepared using high-molecular weight Poly (acrylic acid) as improved binder and ethanol as low cost and environmentally friendly solvent. The evaluation of electrochemical properties shows high specific capacity values of 857 mA hg À1 after 200 cycles at a specific current of 462 mAg À1 , as well as an excellent rate capability with specific current values up to 18480 mAg À1. To the best of our knowledge, this is the first report of Fe 3 O 4 nanoparticles cycling with PAA as binder.
Research Interests:
A composite Pt/Cs 3 H 2 PMo 10 V 2 O 40 catalyst for PEMFC is prepared. Electrochemical characterization with RRDE and Fuel Cell is performed. The polyoxometalates co-catalyst enhances Pt dispersion. The catalyst shows enhanced and... more
A composite Pt/Cs 3 H 2 PMo 10 V 2 O 40 catalyst for PEMFC is prepared. Electrochemical characterization with RRDE and Fuel Cell is performed. The polyoxometalates co-catalyst enhances Pt dispersion. The catalyst shows enhanced and durable activity toward ORR process. The proposed catalyst allows to reduce Pt content maintaining performance. a b s t r a c t The catalytic activity of commercial Pt nanoparticles mixed with mesoporous polyoxometalate Cs 3 H 2 PMo 10 V 2 O 40 towards oxygen reduction reaction is evaluated. The polyoxometalate co-catalyst is prepared by titration of an aqueous solution of phosphovanadomolibdic acid. SEM micrography shows reduction particle size to less than 300 nm, while XRD confirms that the resulting salt maintains the Kegging structure. The composite catalyst is prepared by mixing the POM salt with Pt/C by sonication. RRDE studies show better kinetics for ORR with low Pt loading at the electrode surface. A MEA is assembled by using a Pt/POM-based cathode, in order to assess performance in a working fuel cell. Current vs. potential curves reveals comparable or better performances at 100%, 62% and 17% relative humidity for the POM-modified MEA with respect to a commercial MEA with higher Pt loading at the cathode. Electrochemical impedance spectroscopy (EIS) confirms better kinetics at low relative humidity. Finally, an accelerated stress test (AST) with square wave (SW) between 0.4 V and 0.8 V is performed to evaluate MEA stability for at least 100 h and make predictions about lifetime, showing that after initial losses the catalytic system can retain stable performance and good morphological stability.
Research Interests:
Advanced metal oxide electrodes in Li-ion batteries usually show reversible capacities exceeding the theoretically expected ones. Despite many studies and tentative interpretations, the origin of this extra-capacity is not assessed yet.... more
Advanced metal oxide electrodes in Li-ion batteries usually show reversible capacities exceeding the theoretically expected ones. Despite many studies and tentative interpretations, the origin of this extra-capacity is not assessed yet. Lithium storage can be increased through different chemical processes developing in the electrodes during charging cycles. The solid electrolyte interface (SEI), formed already during the first lithium uptake, is usually considered to be a passivation layer preventing the oxidation of the electrodes while not participating in the lithium storage process. In this work, we combine high resolution soft X-ray absorption spectroscopy with tunable probing depth and photoemission spectroscopy to obtain profiles of the surface evolution of a well-known prototype conversion-alloying type mixed metal oxide (carbon coated ZnFe2O4) electrode. We show that a partially reversible layer of alkyl lithium carbonates is formed (∼5-7 nm) at the SEI surface when reachin...
Research Interests:
Research Interests:
A polyoxometalates (POM) of Kegging-type structure, Cs 3 HPMo 11 VO 40 has been tested as mesoporous matrix to increase Pt electrocatalytic activity, by the enhancement of particles dispersion and active area. Physicochemical... more
A polyoxometalates (POM) of Kegging-type structure, Cs 3 HPMo 11 VO 40 has been tested as mesoporous matrix to increase Pt electrocatalytic activity, by the enhancement of particles dispersion and active area. Physicochemical characterization has been carried out to clarify the structural properties of the matrix. SEM micrograph demonstrated a big change of the morphological features identifying POMs crystals with diameter less than 500 nm. The composite catalyst has been prepared by mixing the polyoxometalates with Pt/Vulcan XC72-R catalyst. By RRDE studies, an improvement in catalytic activity has been observed, both for HOR and ORR, for the layer modified with polyoxometalate matrix. Carbon monoxide adsorption/desorption processes have been also studied in order to evaluate any possible effect towards CO poisoning. Finally, the behavior of a fuel cell, prepared with a POM-modified cathode, was evaluated at 100% relative humidity, revealing that a lower Pt loading can be applied in presence of POM co-catalyst, yielding uncompromised and durable performance.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
ABSTRACT The electrochemical behavior of a composite anode based on tin oxide nanoparticles embedded in electrically conductive graphene matrix is reported. The composite has been synthetized through microwave reduction of poly acrylic... more
ABSTRACT The electrochemical behavior of a composite anode based on tin oxide nanoparticles embedded in electrically conductive graphene matrix is reported. The composite has been synthetized through microwave reduction of poly acrylic acid functionalized graphene oxide and a tin oxide organic precursor both dispersed in ethylene glycol. The poly acrylic functionalization of graphene oxidepartially prevent the re-stacking of the graphene layers. In addition,poly acrylic acid acts as a surfactant favoring an optimized dispersion of the metal and, after thermal decomposition, contributes in creating a carbon layer for an improved conductivity. The final product morphology reveals a composite in which SnO2 nanoparticles are homogenously distributed into the reduced graphene oxide matrix. Graphene/SnO2nanocomposite electrodes, prepared using Super-P carbon as conducting additive and polyvinylidenedifluoride as binder, exhibit high rate capability and cycle life during galvanostatic charge/discharge tests. After more than 140 cycles, mostly performed at 500 mA g−1, the electrodes show a remarkable stable specific capacity of about 430 mAh g−1with a Coulombic efficiency close to 100%.The morphological stability of the electrode is also confirmed by impedance spectroscopy analysis, which shows solid-electrolyte interphase related resistance values constant up to 100 cycles.
Research Interests:
ABSTRACT Synthetic LiFe1-xZnxPO4 (0 ≤ x ≤ 0.26) samples have been prepared using wet chemistry method. The samples have been characterized by means of Rietveld structure refinement of Powder-XRD data and by Mössbauer spectroscopy.... more
ABSTRACT Synthetic LiFe1-xZnxPO4 (0 ≤ x ≤ 0.26) samples have been prepared using wet chemistry method. The samples have been characterized by means of Rietveld structure refinement of Powder-XRD data and by Mössbauer spectroscopy. Impurities such as Li3PO4 and Fe2P have been detected in small amount and quantified by Rietveld analysis. No Zn-bearing impurity has been detected up to x = 0.15, but significant amounts of LiZnPO4 have been observed in the samples with x ≥ 0.2. The unit cell volume of LiFePO4 decreases anisotropically with increasing Zn content (−0.7% of initial volume of 291.343 Å3). Cell parameter (orthorhombic Pbnm space group, #62) b0 and c0 decrease with increasing Zn content, whereas a0 parameter is almost constant. The average &lt;Li–O&gt; and &lt;Fe–O&gt; interatomic distances in the M1 and M2 sites are almost constant, whereas the &lt;P–O&gt; distance slightly decreases (−1.4% of the initial value). Interestingly, O2–O1–O2 bond angle along the [001] direction decreases with increasing Zn-content, thus resulting in a marked decrease of the c0 axis length although the distance remains essentially constant. Mössbauer analyses show the majority of Fe to be divalent and located in an octahedral site similar to available literature data for LiFePO4. The Fe3+/(Fe3++Fe2+) ratio ranges from 0.10 to 0.17, and is not related to the Zn content. Preliminary electrochemical analyses of Zn doped samples in comparison to pristine LiFePO4 are reported.
Research Interests:
Research Interests:
ABSTRACT An advanced lithium ion battery using nanostructured tin–carbon lithium alloying anode and high voltage LiNi0.5Mn1.5O4 spinel-type cathode is studied, with particular focus to the low temperature range. The stable behavior of the... more
ABSTRACT An advanced lithium ion battery using nanostructured tin–carbon lithium alloying anode and high voltage LiNi0.5Mn1.5O4 spinel-type cathode is studied, with particular focus to the low temperature range. The stable behavior of the battery is assured by the use of an electrolyte media based on a LiPF6 salt dissolved in EC-DEC-DMC, i.e. a mixture particularly suitable for the low temperature application. Cycling tests, both in half cells and in full lithium ion battery using the Sn–C anode and the LiNi0.5Mn1.5O4 cathode, performed in a temperature range extending from room temperature to −30 °C, indicate that the electrode/electrolyte configuration here adopted may be suitable for effective application in the lithium ion battery field. The full cell, cycled at −5 °C, shows stable capacity of about 105 mAh g−1 over more than 200 charge–discharge cycles that is a relevant performance considering the low temperature used for the study.
Research Interests:
Research Interests:
ABSTRACT An original method, based on the energy-dispersive X-ray diffraction, has been recently proposed as a possible laboratory tool to accomplish long time resolved investigation of the water content in a proton exchange membrane fuel... more
ABSTRACT An original method, based on the energy-dispersive X-ray diffraction, has been recently proposed as a possible laboratory tool to accomplish long time resolved investigation of the water content in a proton exchange membrane fuel cell. However, this method has never been applied to a real working fuel cell. Therefore, a clear comprehension of its effectiveness in terms of relevant parameters such as time and space resolution, sensitivity, and reproducibility has not yet been achieved. In this paper, all these aspects are discussed and clarified. In order to focus on the method overall effectiveness and on the extent of possible improvements, a basic experimental configuration for both the electrochemical station and the X-ray equipment has been set. The method is described with particular attention to its operating principle and to the evaluation of the errors introduced in data assessment. Finally, applications to some model experiments, in particular working states of the device, are provided and the obtained results are discussed.
Research Interests:
Page 1. RICERCA DI SISTEMA ELETTRICO Ricerca di materiali anodici avanzati per celle a litio e preparazione di celle da laboratorio M. Marinaro, R. Marassi, F. Nobili, R. Tossici Report RdS/2011/299 Agenzia Nazionale ...
... 5) Amatucci, GG; Tarascon, JM; Uchida, I. J. Electrochem. Soc. 1996, 143, 1114. ...
Research Interests:
In-situ X-ray and AC-impedance spectra have been obtained simultaneously during the deintercalation of lithium from LiCoO2 using a specially designed electrochemical cell. The AC-dispersions have been correlated with the cell parameters... more
In-situ X-ray and AC-impedance spectra have been obtained simultaneously during the deintercalation of lithium from LiCoO2 using a specially designed electrochemical cell. The AC-dispersions have been correlated with the cell parameters obtained from the X-ray spectra. The correlation confirms previous hypothesis on the interpretation of the AC-dispersions in terms of an equivalent circuit comprising an element that relates the change of the intrinsic electronic conductivity, occurring at the early stages of deintercalation, to the semiconductor to metal transition caused by the change of the cell parameters.
Research Interests:
ABSTRACT The complex sol–gel technique is applied to the preparation of Mg-/Zr-doped LiCoO2 cobaltites. The synthesis results in composite powders in which the cathodic material is intimately mixed with inactive metal oxides as Co3O4, MgO... more
ABSTRACT The complex sol–gel technique is applied to the preparation of Mg-/Zr-doped LiCoO2 cobaltites. The synthesis results in composite powders in which the cathodic material is intimately mixed with inactive metal oxides as Co3O4, MgO and ZrO2. Cycling ability of the electrodes is evaluated by chronopotentiometry at different currents and potentials, revealing an improved stability of the electrode surface for the Mg-/Zr-doped cathode. Kinetics is investigated by cyclic voltammetry and electrochemical impedance spectroscopy, revealing improvements both in bulk and interfacial transport properties. This behavior can be explained by the concomitant effects of Zr4+ doping and of morphology modifications induced by inactive MgO and ZrO2 oxides dispersion.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
ABSTRACT Copper nanoparticles supported on Super-P carbon (Cu/Super-P) are prepared by a one-pot microwave assisted procedure and used as conductive additive in graphite anodes for lithium-ion batteries. Anodes prepared with the... more
ABSTRACT Copper nanoparticles supported on Super-P carbon (Cu/Super-P) are prepared by a one-pot microwave assisted procedure and used as conductive additive in graphite anodes for lithium-ion batteries. Anodes prepared with the Cu/Super-P additive show excellent cycling stability at temperatures as low as −30 °C with reversible capacities of the order of 180 mAh g−1. Four-points probe DC resistance measurements of layers prepared with Cu/Super-P demonstrate that the electronic resistance decreases of about half with respect to layers prepared with pristine Super-P. Additionally, the ac-impedance of Cu-modified electrodes is much lower than that of electrodes containing Super-P only. This implies an active role of the copper nanoparticles in improving the intercalation capacity, especially at low temperature.