G. Appetecchi - Academia.edu (original) (raw)

Papers by G. Appetecchi

Journal of Macromolecular Science, Part B, 1997

The crystallization kinetics of poly(ethylene oxide) doped with various alkaline perchlorate salt... more The crystallization kinetics of poly(ethylene oxide) doped with various alkaline perchlorate salts were measured at room temperature by means of the new energy dispersive x-ray diffraction method for the phase transition. The experimental points of the transformation coordinate were fitted using the phenomenological Liquori-Tripiciano law, the parameters of which were evaluated for each case. The influence of the concentration and

Solvent-free P(EO) 20 LiTFSI + PYR 14 TFSI polymer electrolyte films with PYR 14 + /Li + mole rat... more Solvent-free P(EO) 20 LiTFSI + PYR 14 TFSI polymer electrolyte films with PYR 14 + /Li + mole ratios ranging from 0.96 to 3.22 were prepared by hot-pressing mixtures composed of PEO, LiTFSI and PYR 14 TFSI of selected stoichiometries. The PYR 14 TFSI room temperature ionic liquid (RTIL) is homogeneously incorporated into the P(EO) 20 LiTFSI membrane without phase separation. For a PYR 14 + /Li + mole ratio of 3.22, the ionic conductivity was about 2 × 10 −4 S/cm at 20 • C, i.e., more than one order of magnitude higher than that of the RTIL-free electrolyte. The electrochemical stability window of the polymer electrolyte containing the RTIL was about 6 V (versus Ag/Ag + ). Li/V 2 O 5 cells with the polymer electrolyte (PYR 14 + /Li + = 1.92) showed a 60% capacity retention after 80 cycles at 40 • C (the initial capacity was 210 mA h/g). Li/V 2 O 5 cells (PYR 14 + /Li + = 1.28) held at 30 • C delivered about 93 mA h/g (at 0.057 mA/cm 2 ), which corresponds to approximately 34% utilization of the active material. These results suggest that the incorporation of the RTILs into PEO-based polymer electrolytes is very promising for the future realization of solid-state lithium metal polymer batteries operating near ambient temperatures.

Electrochimica Acta, 2004

The investigation of chemically cross-linked, self-supporting gel-type electrolyte membranes, bas... more The investigation of chemically cross-linked, self-supporting gel-type electrolyte membranes, based on hybrid polyfluorosilicone polymers reinforced with nanosized silica, for lithium-ion battery systems is reported. The polyfluorosilicone materials were selected on the basis of their high chemical and thermal stabilities. The precursors were synthesized with functional groups capable to form inter-molecular cross-linking, thus obtaining three-dimensional polymer matrices. The latter were undergone to swelling processes in (non-aqueous, lithium salt containing) electrolytic solutions to obtain gel-type polymer electrolytes. Several kinds of membranes, based on different types of polyfluorosilicone precursor, were prepared and characterized in terms of swelling behavior, ionic conductivity and electrochemical stability. The properties of the swelled matrices were evaluated as a function of dipping time, temperature, kind of electrolytic solution and cross-linking initiator content.

Electrochimica Acta, 2008

Although research in the field of ionic liquids for electrochemical applications has led to a dee... more Although research in the field of ionic liquids for electrochemical applications has led to a deeper knowledge in their electrochemical properties, doubts in the interpretation of the experimental results are still encountered in the literature due to the poor control of the experimental conditions and/or to the limited number of experiments conducted. In this work, the effect of water and oxygen traces on the cathodic stability window of hydrophobic, air-stable ionic liquids composed of N-alkyl-N-methylpyrrolidinium (PYR 1A + ) cations and bis(trifluoromethanesulfonyl)imide (TFSI − ) anion, is reported. The extensive investigation performed by linear sweep voltammetry (LSV) and cyclic voltammetry (CV) indicates that the TFSI − anion is cathodically stable if the ionic liquid is pure and dry. The N-alkyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide ionic liquids investigated showed featureless cathodic linear sweep voltammetry curves before the massive cation decomposition took place at very low potentials.

Electrochemistry Communications, 2007

Poly-o-phenylenediamine (PoPD) thin films were synthesized electrochemically on platinum electrod... more Poly-o-phenylenediamine (PoPD) thin films were synthesized electrochemically on platinum electrodes in the room temperature ionic liquid (IL) N-butyl-N-methylpyrrolidinium (nonafluorobutanesulfonyl)-(trifluoromethanesulfonyl)imide (PYR 14 IM 14 ). The polymer films were further characterized by electrochemical analysis and the results are compared with those obtained in conventional H 2 SO 4 aqueous solution. The polymer films obtained in the IL-based electrolyte showed a good adherence on Pt and appeared attractive for the realization of biosensors since they showed a good selectivity with respect to the most common interferent compounds. PoPD films deposited from IL-based electrolytes were investigated in solutions containing compounds as ascorbate and acetaminophen, which are common interferents in electrochemical biosensor analysis, and proved satisfying for application in biosensors.

The Journal of Physical Chemistry B, 2008

Two ionic liquids based upon N-alkyl-N-methylpyrrolidinium cations (PY(1R)(+)) (R=3 for propyl or... more Two ionic liquids based upon N-alkyl-N-methylpyrrolidinium cations (PY(1R)(+)) (R=3 for propyl or 4 for butyl) and the bis(fluorosulfonyl)imide (FSI(-)), N(SO2F)2(-), anion have been extensively characterized. The ionic conductivity and viscosity of these materials are found to be among the highest and lowest, respectively, reported for aprotic ionic liquids. Both ionic liquids crystallize readily on cooling and undergo several solid-solid phase transitions on heating prior to melting. PY13FSI and PY14FSI are found to melt at -9 and -18 degrees C, respectively. The thermal stability of PY13FSI and PY14FSI is notably lower than for the analogous salts with the bis(trifluoromethanesulfonyl)imide (TFSI(-)), N(SO2CF3)2(-), anion. Both ionic liquids have a relatively wide electrochemical stability window of approximately 5 V.

European Polymer Journal, 2008

A new ternary polymer electrolyte based on thermally cross-linked poly(urethane acrylate) (PUA), ... more A new ternary polymer electrolyte based on thermally cross-linked poly(urethane acrylate) (PUA), lithium bis(trifluoromethansulfonyl)imide (LiTFSI) and the ionic liquid N-butyl-Nmethylpyrrolidinium TFSI (PYR 14 TFSI) was developed and tested for application in LMP batteries. The polymer electrolyte was a transparent yellow self-standing material with quite good mechanical properties, i.e., comparable to that of a flexible rubber. The room temperature ionic conductivity of the dry polymer electrolyte was found to be as high as 0.1 mS cm À1 for the compound containing 40 wt% of ionic liquid (PYR 14 TFSI) and a O/Li ratio of 15/1 (Li + from LiTFSI). The thermal analysis of the new cross-linked electrolyte showed that it was homogeneous, amorphous and stable over a wide temperature range extending from À40°C to 100°C. The homogeneity of the polymer electrolyte was also confirmed by SEM analysis.

Faraday Discussions, 2013

Room temperature ionic liquids are one of the most exciting classes of materials in the last deca... more Room temperature ionic liquids are one of the most exciting classes of materials in the last decade. The interest for these low melting, ionic compounds stems from both their technological impact and the stimulating plethora of structural and dynamic peculiarities in the mesoscopic space-time scales. It is nowadays well-established that they are characterised by an enhanced degree of mesoscopic order originating from their inherent amphiphilicity. In this contribution we highlight the existence of a further degree of mesoscopic complexity when dealing with RTILs bearing a medium length fluorous tail: such triphilic materials (they simultaneously contain polar, hydrophobic and fluorophilic moieties that mutually segregate from each other) turn out to be highly structurally compartmentalised at the mesoscopic level, thus paving the way to new smart applications for this new class of RTILs.

Ionics, 1996

Gel electrolytes have been obtained, containing LiX (X = CIO4, N(CF3SO) 2, AsF 6) dissolved in a ... more Gel electrolytes have been obtained, containing LiX (X = CIO4, N(CF3SO) 2, AsF 6) dissolved in a ethylene carbonate-propylene carbonate mixture and PMMA as polymeric matrix. Ionic conductivity has been measured, for two different lithium salts. The changes in the Raman spectra have been studied as a function of the polymer content, lithium salt concentrations and for different anions. Two satellite bands of the internal bending and stretching modes of ethylene carbonate appear in the spectrum of lithium containing samples, because of the cation-solvent molecule interaction.

Electrolytes consisting of low molecular weight perfluoropolyether (PFPE), poly(ethylene glycol) ... more Electrolytes consisting of low molecular weight perfluoropolyether (PFPE), poly(ethylene glycol) (PEG), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) blends were prepared and systematically studied for salt concentration and stoichiometry effects on the materials' thermal and electrochemical properties. Herein we report that the tunable ratios of PFPE and PEG allow for precise control of crystalline melting and glass transition temperature properties. These blended liquid polymer electrolytes are inherently nonflammable and remain stable in the amorphous phase from approximately 150°C down to −85°C. The ionic conductivity of the electrolytes are on the order of 10 −4 S/cm at 30°C, which makes them suitable for rechargeable lithium batteries.

Solid State Ionics, 2001

Three new types of polymer electrolyte lithium-ion batteries are presented and discussed. These b... more Three new types of polymer electrolyte lithium-ion batteries are presented and discussed. These batteries have been Ž . prepared by using gel-type, poly acrylonitrile , PAN-based membranes as the electrolyte separators of various electrode ombinations. The latter include 'standard' materials such as a graphite Li C anode and a manganese spinel LiMn O x 6 2 4 cathode, as well as more innovative electrodes such as KC and SnO anodes, and LiCr Mn O and LiNi Co O 8 2 y 2yy 4 y 1yy 2

Journal of Macromolecular Science, Part B, 1997

Electrochimica Acta, 2004

The investigation of chemically cross-linked, self-supporting gel-type electrolyte membranes, bas... more The investigation of chemically cross-linked, self-supporting gel-type electrolyte membranes, based on hybrid polyfluorosilicone polymers reinforced with nanosized silica, for lithium-ion battery systems is reported. The polyfluorosilicone materials were selected on the basis of their high chemical and thermal stabilities. The precursors were synthesized with functional groups capable to form inter-molecular cross-linking, thus obtaining three-dimensional polymer matrices. The latter were undergone to swelling processes in (non-aqueous, lithium salt containing) electrolytic solutions to obtain gel-type polymer electrolytes. Several kinds of membranes, based on different types of polyfluorosilicone precursor, were prepared and characterized in terms of swelling behavior, ionic conductivity and electrochemical stability. The properties of the swelled matrices were evaluated as a function of dipping time, temperature, kind of electrolytic solution and cross-linking initiator content.

Electrochemistry Communications, 1999

Battery-grade solution products have been used for the synthesis of new types of poly(acrylonitri... more Battery-grade solution products have been used for the synthesis of new types of poly(acrylonitrile) PAN-based polymer electrolyte membranes. Basically, two classes of membranes have been prepared differing by the type of lithium salt in the ethylene carbonate-dimethyl carbonate (EC-DMC) solution trapped in the PAN matrix, i.e. LiPF 6 or LiC(CF 3 SO 2 ) 3 lithium methide salt, respectively. The results demonstrate that both classes of membranes have high conductivity and very good chemical and electrochemical stability. These unique characteristics make the membranes suitable for applications in high-voltage, rechargeable lithium batteries.

Faraday Discussions, 2013

Room temperature ionic liquids are one of the most exciting classes of materials in the last deca... more Room temperature ionic liquids are one of the most exciting classes of materials in the last decade. The interest for these low melting, ionic compounds stems from both their technological impact and the stimulating plethora of structural and dynamic peculiarities in the mesoscopic space-time scales. It is nowadays well-established that they are characterised by an enhanced degree of mesoscopic order originating from their inherent amphiphilicity. In this contribution we highlight the existence of a further degree of mesoscopic complexity when dealing with RTILs bearing a medium length fluorous tail: such triphilic materials (they simultaneously contain polar, hydrophobic and fluorophilic moieties that mutually segregate from each other) turn out to be highly structurally compartmentalised at the mesoscopic level, thus paving the way to new smart applications for this new class of RTILs.

Journal of Macromolecular Science, Part B, 1997

The crystallization kinetics of poly(ethylene oxide) doped with various alkaline perchlorate salt... more The crystallization kinetics of poly(ethylene oxide) doped with various alkaline perchlorate salts were measured at room temperature by means of the new energy dispersive x-ray diffraction method for the phase transition. The experimental points of the transformation coordinate were fitted using the phenomenological Liquori-Tripiciano law, the parameters of which were evaluated for each case. The influence of the concentration and

Solvent-free P(EO) 20 LiTFSI + PYR 14 TFSI polymer electrolyte films with PYR 14 + /Li + mole rat... more Solvent-free P(EO) 20 LiTFSI + PYR 14 TFSI polymer electrolyte films with PYR 14 + /Li + mole ratios ranging from 0.96 to 3.22 were prepared by hot-pressing mixtures composed of PEO, LiTFSI and PYR 14 TFSI of selected stoichiometries. The PYR 14 TFSI room temperature ionic liquid (RTIL) is homogeneously incorporated into the P(EO) 20 LiTFSI membrane without phase separation. For a PYR 14 + /Li + mole ratio of 3.22, the ionic conductivity was about 2 × 10 −4 S/cm at 20 • C, i.e., more than one order of magnitude higher than that of the RTIL-free electrolyte. The electrochemical stability window of the polymer electrolyte containing the RTIL was about 6 V (versus Ag/Ag + ). Li/V 2 O 5 cells with the polymer electrolyte (PYR 14 + /Li + = 1.92) showed a 60% capacity retention after 80 cycles at 40 • C (the initial capacity was 210 mA h/g). Li/V 2 O 5 cells (PYR 14 + /Li + = 1.28) held at 30 • C delivered about 93 mA h/g (at 0.057 mA/cm 2 ), which corresponds to approximately 34% utilization of the active material. These results suggest that the incorporation of the RTILs into PEO-based polymer electrolytes is very promising for the future realization of solid-state lithium metal polymer batteries operating near ambient temperatures.

Electrochimica Acta, 2004

The investigation of chemically cross-linked, self-supporting gel-type electrolyte membranes, bas... more The investigation of chemically cross-linked, self-supporting gel-type electrolyte membranes, based on hybrid polyfluorosilicone polymers reinforced with nanosized silica, for lithium-ion battery systems is reported. The polyfluorosilicone materials were selected on the basis of their high chemical and thermal stabilities. The precursors were synthesized with functional groups capable to form inter-molecular cross-linking, thus obtaining three-dimensional polymer matrices. The latter were undergone to swelling processes in (non-aqueous, lithium salt containing) electrolytic solutions to obtain gel-type polymer electrolytes. Several kinds of membranes, based on different types of polyfluorosilicone precursor, were prepared and characterized in terms of swelling behavior, ionic conductivity and electrochemical stability. The properties of the swelled matrices were evaluated as a function of dipping time, temperature, kind of electrolytic solution and cross-linking initiator content.

Electrochimica Acta, 2008

Although research in the field of ionic liquids for electrochemical applications has led to a dee... more Although research in the field of ionic liquids for electrochemical applications has led to a deeper knowledge in their electrochemical properties, doubts in the interpretation of the experimental results are still encountered in the literature due to the poor control of the experimental conditions and/or to the limited number of experiments conducted. In this work, the effect of water and oxygen traces on the cathodic stability window of hydrophobic, air-stable ionic liquids composed of N-alkyl-N-methylpyrrolidinium (PYR 1A + ) cations and bis(trifluoromethanesulfonyl)imide (TFSI − ) anion, is reported. The extensive investigation performed by linear sweep voltammetry (LSV) and cyclic voltammetry (CV) indicates that the TFSI − anion is cathodically stable if the ionic liquid is pure and dry. The N-alkyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide ionic liquids investigated showed featureless cathodic linear sweep voltammetry curves before the massive cation decomposition took place at very low potentials.

Electrochemistry Communications, 2007

Poly-o-phenylenediamine (PoPD) thin films were synthesized electrochemically on platinum electrod... more Poly-o-phenylenediamine (PoPD) thin films were synthesized electrochemically on platinum electrodes in the room temperature ionic liquid (IL) N-butyl-N-methylpyrrolidinium (nonafluorobutanesulfonyl)-(trifluoromethanesulfonyl)imide (PYR 14 IM 14 ). The polymer films were further characterized by electrochemical analysis and the results are compared with those obtained in conventional H 2 SO 4 aqueous solution. The polymer films obtained in the IL-based electrolyte showed a good adherence on Pt and appeared attractive for the realization of biosensors since they showed a good selectivity with respect to the most common interferent compounds. PoPD films deposited from IL-based electrolytes were investigated in solutions containing compounds as ascorbate and acetaminophen, which are common interferents in electrochemical biosensor analysis, and proved satisfying for application in biosensors.

The Journal of Physical Chemistry B, 2008

Two ionic liquids based upon N-alkyl-N-methylpyrrolidinium cations (PY(1R)(+)) (R=3 for propyl or... more Two ionic liquids based upon N-alkyl-N-methylpyrrolidinium cations (PY(1R)(+)) (R=3 for propyl or 4 for butyl) and the bis(fluorosulfonyl)imide (FSI(-)), N(SO2F)2(-), anion have been extensively characterized. The ionic conductivity and viscosity of these materials are found to be among the highest and lowest, respectively, reported for aprotic ionic liquids. Both ionic liquids crystallize readily on cooling and undergo several solid-solid phase transitions on heating prior to melting. PY13FSI and PY14FSI are found to melt at -9 and -18 degrees C, respectively. The thermal stability of PY13FSI and PY14FSI is notably lower than for the analogous salts with the bis(trifluoromethanesulfonyl)imide (TFSI(-)), N(SO2CF3)2(-), anion. Both ionic liquids have a relatively wide electrochemical stability window of approximately 5 V.

European Polymer Journal, 2008

A new ternary polymer electrolyte based on thermally cross-linked poly(urethane acrylate) (PUA), ... more A new ternary polymer electrolyte based on thermally cross-linked poly(urethane acrylate) (PUA), lithium bis(trifluoromethansulfonyl)imide (LiTFSI) and the ionic liquid N-butyl-Nmethylpyrrolidinium TFSI (PYR 14 TFSI) was developed and tested for application in LMP batteries. The polymer electrolyte was a transparent yellow self-standing material with quite good mechanical properties, i.e., comparable to that of a flexible rubber. The room temperature ionic conductivity of the dry polymer electrolyte was found to be as high as 0.1 mS cm À1 for the compound containing 40 wt% of ionic liquid (PYR 14 TFSI) and a O/Li ratio of 15/1 (Li + from LiTFSI). The thermal analysis of the new cross-linked electrolyte showed that it was homogeneous, amorphous and stable over a wide temperature range extending from À40°C to 100°C. The homogeneity of the polymer electrolyte was also confirmed by SEM analysis.

Faraday Discussions, 2013

Room temperature ionic liquids are one of the most exciting classes of materials in the last deca... more Room temperature ionic liquids are one of the most exciting classes of materials in the last decade. The interest for these low melting, ionic compounds stems from both their technological impact and the stimulating plethora of structural and dynamic peculiarities in the mesoscopic space-time scales. It is nowadays well-established that they are characterised by an enhanced degree of mesoscopic order originating from their inherent amphiphilicity. In this contribution we highlight the existence of a further degree of mesoscopic complexity when dealing with RTILs bearing a medium length fluorous tail: such triphilic materials (they simultaneously contain polar, hydrophobic and fluorophilic moieties that mutually segregate from each other) turn out to be highly structurally compartmentalised at the mesoscopic level, thus paving the way to new smart applications for this new class of RTILs.

Ionics, 1996

Gel electrolytes have been obtained, containing LiX (X = CIO4, N(CF3SO) 2, AsF 6) dissolved in a ... more Gel electrolytes have been obtained, containing LiX (X = CIO4, N(CF3SO) 2, AsF 6) dissolved in a ethylene carbonate-propylene carbonate mixture and PMMA as polymeric matrix. Ionic conductivity has been measured, for two different lithium salts. The changes in the Raman spectra have been studied as a function of the polymer content, lithium salt concentrations and for different anions. Two satellite bands of the internal bending and stretching modes of ethylene carbonate appear in the spectrum of lithium containing samples, because of the cation-solvent molecule interaction.

Electrolytes consisting of low molecular weight perfluoropolyether (PFPE), poly(ethylene glycol) ... more Electrolytes consisting of low molecular weight perfluoropolyether (PFPE), poly(ethylene glycol) (PEG), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) blends were prepared and systematically studied for salt concentration and stoichiometry effects on the materials' thermal and electrochemical properties. Herein we report that the tunable ratios of PFPE and PEG allow for precise control of crystalline melting and glass transition temperature properties. These blended liquid polymer electrolytes are inherently nonflammable and remain stable in the amorphous phase from approximately 150°C down to −85°C. The ionic conductivity of the electrolytes are on the order of 10 −4 S/cm at 30°C, which makes them suitable for rechargeable lithium batteries.

Solid State Ionics, 2001

Three new types of polymer electrolyte lithium-ion batteries are presented and discussed. These b... more Three new types of polymer electrolyte lithium-ion batteries are presented and discussed. These batteries have been Ž . prepared by using gel-type, poly acrylonitrile , PAN-based membranes as the electrolyte separators of various electrode ombinations. The latter include 'standard' materials such as a graphite Li C anode and a manganese spinel LiMn O x 6 2 4 cathode, as well as more innovative electrodes such as KC and SnO anodes, and LiCr Mn O and LiNi Co O 8 2 y 2yy 4 y 1yy 2

Journal of Macromolecular Science, Part B, 1997

Electrochimica Acta, 2004

The investigation of chemically cross-linked, self-supporting gel-type electrolyte membranes, bas... more The investigation of chemically cross-linked, self-supporting gel-type electrolyte membranes, based on hybrid polyfluorosilicone polymers reinforced with nanosized silica, for lithium-ion battery systems is reported. The polyfluorosilicone materials were selected on the basis of their high chemical and thermal stabilities. The precursors were synthesized with functional groups capable to form inter-molecular cross-linking, thus obtaining three-dimensional polymer matrices. The latter were undergone to swelling processes in (non-aqueous, lithium salt containing) electrolytic solutions to obtain gel-type polymer electrolytes. Several kinds of membranes, based on different types of polyfluorosilicone precursor, were prepared and characterized in terms of swelling behavior, ionic conductivity and electrochemical stability. The properties of the swelled matrices were evaluated as a function of dipping time, temperature, kind of electrolytic solution and cross-linking initiator content.

Electrochemistry Communications, 1999

Battery-grade solution products have been used for the synthesis of new types of poly(acrylonitri... more Battery-grade solution products have been used for the synthesis of new types of poly(acrylonitrile) PAN-based polymer electrolyte membranes. Basically, two classes of membranes have been prepared differing by the type of lithium salt in the ethylene carbonate-dimethyl carbonate (EC-DMC) solution trapped in the PAN matrix, i.e. LiPF 6 or LiC(CF 3 SO 2 ) 3 lithium methide salt, respectively. The results demonstrate that both classes of membranes have high conductivity and very good chemical and electrochemical stability. These unique characteristics make the membranes suitable for applications in high-voltage, rechargeable lithium batteries.

Faraday Discussions, 2013

Room temperature ionic liquids are one of the most exciting classes of materials in the last deca... more Room temperature ionic liquids are one of the most exciting classes of materials in the last decade. The interest for these low melting, ionic compounds stems from both their technological impact and the stimulating plethora of structural and dynamic peculiarities in the mesoscopic space-time scales. It is nowadays well-established that they are characterised by an enhanced degree of mesoscopic order originating from their inherent amphiphilicity. In this contribution we highlight the existence of a further degree of mesoscopic complexity when dealing with RTILs bearing a medium length fluorous tail: such triphilic materials (they simultaneously contain polar, hydrophobic and fluorophilic moieties that mutually segregate from each other) turn out to be highly structurally compartmentalised at the mesoscopic level, thus paving the way to new smart applications for this new class of RTILs.