ABSTRACT The gelation of ionic liquid-based solutions with inorganic or organic fillers is one of... more ABSTRACT The gelation of ionic liquid-based solutions with inorganic or organic fillers is one of the strategies commonly adopted in the Dye-Sensitized Solar Cells (DSSCs) field for preparing quasi-solid electrolytes characterized by good photovoltaic performance and long-term stability. In the present paper, the application of a gel electrolyte based on unmodified microci:ystalline cellulose and ionic liquids in a DSSC is reported. The gel electrolyte has been characterized evaluating its conductive, thermogravimetric, viscous and crystalline properties, while the photoelectrochemical behavior of the quasi-solid DSSCs has been investigated measuring current-voltage, Electrochemical Impedance Spectroscopy and Linear Sweep Voltammetry curves. The photovoltaic performance of cellulose gel-based DSSCs has been optimized by monitoring some key parameters, such as ionic liquid volume ratios and cellulose content. A maximum photoconversion efficiency of 3.33% has been obtained with the total absence of organic solvents, and a good stability has been demonstrated during more than 8 hours of exposition (replicated over months) to simulated solar light. Moreover, a peculiar and reversible trend in the short-circuit current density and in the overall efficiency of the cell has been observed during prolonged photovoltaic measurements. The present findings suggest the necessity to adopt a new protocol for the measurement of the photovoltaic parameters of quasi solid DSSCs.
ABSTRACT A methacrylate based plasticised polymer electrolyte membrane is prepared via a rapid an... more ABSTRACT A methacrylate based plasticised polymer electrolyte membrane is prepared via a rapid and facile UV curing process, the major concerns of mechanical integrity are overcome by simply using appropriately modified cellulose handsheet laden with nano-sized acidic alumina particles as a reinforcement. The use of the cellulose handsheets greatly enhances the flexibility and mechanical properties of the membrane while the addition of alumina particles helps to maintain satisfactory conductivity values. The reinforced composite electrolyte membrane is also tested in a real lithium cell, exhibiting excellent performance which account for its use in futuristic lithium batteries having low cost, environmentally friendly and easily scalable properties.
ABSTRACT Methacrylic-based thermo-set gel-polymer electrolytes obtained by the easy and reliable ... more ABSTRACT Methacrylic-based thermo-set gel-polymer electrolytes obtained by the easy and reliable photo-polymerisation process and mechanically reinforced by a cellulose handsheet (paper) for flexible lithium batteries application are here presented. Adhesion between cellulose and polymer is improved by "in situ" grafting supported by benzophenone; the ionic conductivity of the electrolyte is enhanced by the use of specifically designed handsheets containing alumina. Thermal and mechanical properties of the new membranes are characterised and the effect of the different composition of the reinforcement on the ionic conductivity of the membranes is discussed.
ABSTRACT A novel UV-induced procedure, in the presence of glycidyl acrylate and proper radical/ca... more ABSTRACT A novel UV-induced procedure, in the presence of glycidyl acrylate and proper radical/cationic photoinitiators, is here proposed to promote the in situ grafting of a methacrylic polymer network to the surface of natural cellulose fibers. As a result, composite polymer membranes reinforced by cellulose handsheets are obtained and demonstrate excellent mechanical features. The reactivity of the monomers is studied by FT-IR in real time measurements and the successful grafting is confirmed by surface spectroscopies. The polymer membranes prepared show high elastic modulus and tensile resistance and maintain high flexibility even after activation by swelling into a standard liquid electrolyte solution. The swelling procedure allowed to obtain high ionic conductivity and remarkable electrochemical behavior when tested in laboratory scale lithium polymer cells. The system shows attractive features such as intrinsic safety, eco-compatibility, and low production cost and industrialization potentials, highly suitable in the rapidly expanding field of Li-based flexible batteries.
ABSTRACT Nanoscale microfibrillated cellulose (NMFC) was introduced into a light-cured polymeric ... more ABSTRACT Nanoscale microfibrillated cellulose (NMFC) was introduced into a light-cured polymeric matrix to result in a green, cheap, and highly efficient quasi-solid electrolyte for the next-generation of bio-based dye-sensitized solar cells. The effect of NMFC on the photovoltaic parameters and performance of the resulting photo-electrochemical cells was thoroughly investigated, and a noticeable increase in both the photocurrent (due to optical phenomena) and the photovoltage (through a shielding effect on the recombination reactions) was demonstrated. Upon thorough optimization of the amount of NMFC introduced into the polymeric network, sunlight conversion efficiencies as high as 7.03 and 8.25 % were achieved at simulated light intensities of 1.0 and 0.4 sun, respectively. Furthermore and outstandingly, the addition of NMFC positively affected the long-term stability of the device, which was able to retain >95 % of its initial efficiency after 500 h of extreme aging conditions.
Methacrylic-based thermo-set gel-polymer electrolyte membranes obtained by a very easy, fast and ... more Methacrylic-based thermo-set gel-polymer electrolyte membranes obtained by a very easy, fast and reliable free radical photo-polymerisation process and reinforced with microfibrillated cellulose particles are here presented. The morphology of the composite electrolytes is investigated by scanning electron microscopy and their thermal behaviour (characteristic temperatures, degradation temperature) are investigated by thermo-gravimetric analysis and differential scanning calorimetry. The composite membranes prepared exhibit
ABSTRACT Fully-solid methacrylic-based thermo-set polymer electrolyte membranes reinforced with n... more ABSTRACT Fully-solid methacrylic-based thermo-set polymer electrolyte membranes reinforced with nanoscale micro-fibrillated cellulose (MFC) fibres are here presented. The preparation is carried out in water and the membrane is obtained by an easy and reliable UV-induced polymerisation via a free radical mechanism; thus, the overall process is highly energy efficient and environmentally friendly. The morphology of the composite electrolytes as well as the mapping of the elements present in the system is investigated by scanning electron microscopy, while the thermal behaviour is investigated by thermo-gravimetric analysis and differential scanning calorimetry. The composite polymer electrolytes prepared by MFC fibres reinforcement exhibit excellent mechanical properties with a Young’s modulus as high as 32 MPa. Acceptable ionic conductivity values (above 0.1 mS cm−1 at 50 °C) and good overall electrochemical performances are maintained, ensuring that such specific approach would make these hybrid organic, cellulose-based composite polymer electrolyte systems a strong contender in the field of thin and flexible fully-solid lithium based power sources, especially for moderately high temperature applications. Graphical Abstract
ABSTRACT This work reports the formulation of vinyl ether containing functionalized graphene shee... more ABSTRACT This work reports the formulation of vinyl ether containing functionalized graphene sheets in order to produce UV-curable conductive inks. The best graphene-surfactant ratio was found to give a stable dispersion of graphene into triethyleneglycol divinyl ether (DVE3) resin, avoiding the presence of large filler aggregates that could clog printing head during ink-jet process. Propylene carbonate was used as solvent to adjust the viscosity of the formulation. The presence of graphene did not significantly hindered the UV-curing process. Crosslinked nanocomposite materials show a decrease of resistivity of seven order of magnitude with respect to the pristine polymeric matrix.
ABSTRACT Dielectric elastomer actuator films were fabricated on transparent conductive electrode ... more ABSTRACT Dielectric elastomer actuator films were fabricated on transparent conductive electrode using bi-component poly(dimethyl)siloxane (PDMS). PDMS is a well-known material in microfluidics and soft lithography for biomedical applications, being easy to process, low cost, biocompatible and transparent. Moreover its mechanical properties can be easily tuned by varying the mixing ratio between the oligomer base and the crosslinking agent. In this work we investigate the chemical composition and the electromechanical properties of PDMS thin film verifying for the first time the tuneable actuation response by simply modifying the amount of the curing agent. We demonstrate that, for a 20:1 ratio of base:crosslinker mixture, a striking 150% enhancement of Maxwell strain occurs at 1 Hz actuating frequency.
ABSTRACT The gelation of ionic liquid-based solutions with inorganic or organic fillers is one of... more ABSTRACT The gelation of ionic liquid-based solutions with inorganic or organic fillers is one of the strategies commonly adopted in the Dye-Sensitized Solar Cells (DSSCs) field for preparing quasi-solid electrolytes characterized by good photovoltaic performance and long-term stability. In the present paper, the application of a gel electrolyte based on unmodified microci:ystalline cellulose and ionic liquids in a DSSC is reported. The gel electrolyte has been characterized evaluating its conductive, thermogravimetric, viscous and crystalline properties, while the photoelectrochemical behavior of the quasi-solid DSSCs has been investigated measuring current-voltage, Electrochemical Impedance Spectroscopy and Linear Sweep Voltammetry curves. The photovoltaic performance of cellulose gel-based DSSCs has been optimized by monitoring some key parameters, such as ionic liquid volume ratios and cellulose content. A maximum photoconversion efficiency of 3.33% has been obtained with the total absence of organic solvents, and a good stability has been demonstrated during more than 8 hours of exposition (replicated over months) to simulated solar light. Moreover, a peculiar and reversible trend in the short-circuit current density and in the overall efficiency of the cell has been observed during prolonged photovoltaic measurements. The present findings suggest the necessity to adopt a new protocol for the measurement of the photovoltaic parameters of quasi solid DSSCs.
ABSTRACT A methacrylate based plasticised polymer electrolyte membrane is prepared via a rapid an... more ABSTRACT A methacrylate based plasticised polymer electrolyte membrane is prepared via a rapid and facile UV curing process, the major concerns of mechanical integrity are overcome by simply using appropriately modified cellulose handsheet laden with nano-sized acidic alumina particles as a reinforcement. The use of the cellulose handsheets greatly enhances the flexibility and mechanical properties of the membrane while the addition of alumina particles helps to maintain satisfactory conductivity values. The reinforced composite electrolyte membrane is also tested in a real lithium cell, exhibiting excellent performance which account for its use in futuristic lithium batteries having low cost, environmentally friendly and easily scalable properties.
ABSTRACT Methacrylic-based thermo-set gel-polymer electrolytes obtained by the easy and reliable ... more ABSTRACT Methacrylic-based thermo-set gel-polymer electrolytes obtained by the easy and reliable photo-polymerisation process and mechanically reinforced by a cellulose handsheet (paper) for flexible lithium batteries application are here presented. Adhesion between cellulose and polymer is improved by "in situ" grafting supported by benzophenone; the ionic conductivity of the electrolyte is enhanced by the use of specifically designed handsheets containing alumina. Thermal and mechanical properties of the new membranes are characterised and the effect of the different composition of the reinforcement on the ionic conductivity of the membranes is discussed.
ABSTRACT A novel UV-induced procedure, in the presence of glycidyl acrylate and proper radical/ca... more ABSTRACT A novel UV-induced procedure, in the presence of glycidyl acrylate and proper radical/cationic photoinitiators, is here proposed to promote the in situ grafting of a methacrylic polymer network to the surface of natural cellulose fibers. As a result, composite polymer membranes reinforced by cellulose handsheets are obtained and demonstrate excellent mechanical features. The reactivity of the monomers is studied by FT-IR in real time measurements and the successful grafting is confirmed by surface spectroscopies. The polymer membranes prepared show high elastic modulus and tensile resistance and maintain high flexibility even after activation by swelling into a standard liquid electrolyte solution. The swelling procedure allowed to obtain high ionic conductivity and remarkable electrochemical behavior when tested in laboratory scale lithium polymer cells. The system shows attractive features such as intrinsic safety, eco-compatibility, and low production cost and industrialization potentials, highly suitable in the rapidly expanding field of Li-based flexible batteries.
ABSTRACT Nanoscale microfibrillated cellulose (NMFC) was introduced into a light-cured polymeric ... more ABSTRACT Nanoscale microfibrillated cellulose (NMFC) was introduced into a light-cured polymeric matrix to result in a green, cheap, and highly efficient quasi-solid electrolyte for the next-generation of bio-based dye-sensitized solar cells. The effect of NMFC on the photovoltaic parameters and performance of the resulting photo-electrochemical cells was thoroughly investigated, and a noticeable increase in both the photocurrent (due to optical phenomena) and the photovoltage (through a shielding effect on the recombination reactions) was demonstrated. Upon thorough optimization of the amount of NMFC introduced into the polymeric network, sunlight conversion efficiencies as high as 7.03 and 8.25 % were achieved at simulated light intensities of 1.0 and 0.4 sun, respectively. Furthermore and outstandingly, the addition of NMFC positively affected the long-term stability of the device, which was able to retain >95 % of its initial efficiency after 500 h of extreme aging conditions.
Methacrylic-based thermo-set gel-polymer electrolyte membranes obtained by a very easy, fast and ... more Methacrylic-based thermo-set gel-polymer electrolyte membranes obtained by a very easy, fast and reliable free radical photo-polymerisation process and reinforced with microfibrillated cellulose particles are here presented. The morphology of the composite electrolytes is investigated by scanning electron microscopy and their thermal behaviour (characteristic temperatures, degradation temperature) are investigated by thermo-gravimetric analysis and differential scanning calorimetry. The composite membranes prepared exhibit
ABSTRACT Fully-solid methacrylic-based thermo-set polymer electrolyte membranes reinforced with n... more ABSTRACT Fully-solid methacrylic-based thermo-set polymer electrolyte membranes reinforced with nanoscale micro-fibrillated cellulose (MFC) fibres are here presented. The preparation is carried out in water and the membrane is obtained by an easy and reliable UV-induced polymerisation via a free radical mechanism; thus, the overall process is highly energy efficient and environmentally friendly. The morphology of the composite electrolytes as well as the mapping of the elements present in the system is investigated by scanning electron microscopy, while the thermal behaviour is investigated by thermo-gravimetric analysis and differential scanning calorimetry. The composite polymer electrolytes prepared by MFC fibres reinforcement exhibit excellent mechanical properties with a Young’s modulus as high as 32 MPa. Acceptable ionic conductivity values (above 0.1 mS cm−1 at 50 °C) and good overall electrochemical performances are maintained, ensuring that such specific approach would make these hybrid organic, cellulose-based composite polymer electrolyte systems a strong contender in the field of thin and flexible fully-solid lithium based power sources, especially for moderately high temperature applications. Graphical Abstract
ABSTRACT This work reports the formulation of vinyl ether containing functionalized graphene shee... more ABSTRACT This work reports the formulation of vinyl ether containing functionalized graphene sheets in order to produce UV-curable conductive inks. The best graphene-surfactant ratio was found to give a stable dispersion of graphene into triethyleneglycol divinyl ether (DVE3) resin, avoiding the presence of large filler aggregates that could clog printing head during ink-jet process. Propylene carbonate was used as solvent to adjust the viscosity of the formulation. The presence of graphene did not significantly hindered the UV-curing process. Crosslinked nanocomposite materials show a decrease of resistivity of seven order of magnitude with respect to the pristine polymeric matrix.
ABSTRACT Dielectric elastomer actuator films were fabricated on transparent conductive electrode ... more ABSTRACT Dielectric elastomer actuator films were fabricated on transparent conductive electrode using bi-component poly(dimethyl)siloxane (PDMS). PDMS is a well-known material in microfluidics and soft lithography for biomedical applications, being easy to process, low cost, biocompatible and transparent. Moreover its mechanical properties can be easily tuned by varying the mixing ratio between the oligomer base and the crosslinking agent. In this work we investigate the chemical composition and the electromechanical properties of PDMS thin film verifying for the first time the tuneable actuation response by simply modifying the amount of the curing agent. We demonstrate that, for a 20:1 ratio of base:crosslinker mixture, a striking 150% enhancement of Maxwell strain occurs at 1 Hz actuating frequency.
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Papers by Annalisa Chiappone