SiNWs-based electrochemical double layer micro-supercapacitors with wide voltage window (4V) and long cycling stability using a protic ionic liquid electrolyte

The present work reports the use and application of a novel protic ionic liquid (triethylammonium bis(tri fluoromethylsulfonyl)imide; NEtH TFSI) as an electrolyte for symmetric planar micro-supercapacitors based on silicon nanowire electrodes. The excellent performance of the device has been successfully demonstrated using cyclic voltammetry, galvanostatic charge-discharge cycles and electrochemical impedance spectroscopy. The electrochemical characterization of this system exhibits a wide operative voltage of 4 V as well as an outstanding long cycling stability after millions of galvanostatic cycles at a high current density of 2 mA cm. In addition, the electrochemical double layer micro-supercapacitor was able to deliver a high power density of 4 mWcm in a very short time pulses (a few ms). Our results could be of interest to develop prospective on-chip micro-supercapacitors using protic ionic liquids as electrolytes with high performance in terms of power and energy densities

Gold(I), Gold(III), and Heterometallic Gold(I)–Silver(I) and Gold(I)–Copper(I) Complexes of a Pyridazine-Bridged NHC/Pyrazole Hybrid Ligand and Their Initial Application in Catalysis

The pyridazine-bridged NHC/pyrazole ligand L (HL = 3-[3-(2,4,6-trimethylphenyl)-3<i>H</i>-imidazolium-1-yl]-6-(3,5-dimethylpyrazol-1-yl)-pyridazine) that provides an organometallic and a classical N-donor compartment is shown to serve as a versatile scaffold for a variety of homo- and heterometallic gold­(I) carbene complexes. Complexes [LAuX] (<b>1</b>^<b>Cl</b>, X = Cl; <b>1</b>^<b>Br</b>, X = Br), [L₂Au]­(PF₆) (<b>2</b>), [L₂AuAg]­(BF₄)­(PF₆) (<b>3</b>), [L₂AuAg₃(MeCN)₆]­(BF₄)₄ (<b>5</b>), and [L₂AuCu]­(OTf)_0.75(PF₆)_1.25 (<b>6</b>) have been characterized by X-ray crystallography. In all cases Au­(I) binds to the NHC site while the additional Ag­(I) in <b>3</b> or Cu­(I) in <b>6</b> is accommodated in the pyrazole-derived site. Both <b>3</b> and <b>6</b> form two-stranded helical structures; racemization of the <i>P</i> and <i>M</i> enantiomers is much more facile in the Ag­(I) case <b>3</b> but has a barrier of around 65 kJ/mol in the Cu­(I) case <b>6</b>, which is rationalized on the basis of the different coordination chemistry preferences of these two metal ions. <b>3</b> may bind two further Ag­(I) ions to the central pyridazine N, giving <b>5</b>. Treatment of <b>1</b>^<b>Br</b> with Br₂ leads to bromination at the pyrazole C⁴ of the ligand backbone, yielding [L^BrAuBr] (<b>8</b>). In contrast, <b>1</b>^<b>Cl</b> could be successfully oxidized to the Au­(III) complex [LAuCl₃] (<b>7</b>) using PhICl₂; both <b>7</b> and the gold­(I) complex <b>8</b> have been characterized crystallographically. Preliminary screening shows that <b>7</b>, in combination with AgBF₄, is a good catalyst for the etherification of 1-indanol with a variety of alcohol substrates and shows significantly higher activity than the gold­(I) catalyst <b>1</b>^<b>Cl</b>

Gold(I), Gold(III), and Heterometallic Gold(I)–Silver(I) and Gold(I)–Copper(I) Complexes of a Pyridazine-Bridged NHC/Pyrazole Hybrid Ligand and Their Initial Application in Catalysis

The pyridazine-bridged NHC/pyrazole ligand L (HL = 3-[3-(2,4,6-trimethylphenyl)-3<i>H</i>-imidazolium-1-yl]-6-(3,5-dimethylpyrazol-1-yl)-pyridazine) that provides an organometallic and a classical N-donor compartment is shown to serve as a versatile scaffold for a variety of homo- and heterometallic gold­(I) carbene complexes. Complexes [LAuX] (<b>1</b>^<b>Cl</b>, X = Cl; <b>1</b>^<b>Br</b>, X = Br), [L₂Au]­(PF₆) (<b>2</b>), [L₂AuAg]­(BF₄)­(PF₆) (<b>3</b>), [L₂AuAg₃(MeCN)₆]­(BF₄)₄ (<b>5</b>), and [L₂AuCu]­(OTf)_0.75(PF₆)_1.25 (<b>6</b>) have been characterized by X-ray crystallography. In all cases Au­(I) binds to the NHC site while the additional Ag­(I) in <b>3</b> or Cu­(I) in <b>6</b> is accommodated in the pyrazole-derived site. Both <b>3</b> and <b>6</b> form two-stranded helical structures; racemization of the <i>P</i> and <i>M</i> enantiomers is much more facile in the Ag­(I) case <b>3</b> but has a barrier of around 65 kJ/mol in the Cu­(I) case <b>6</b>, which is rationalized on the basis of the different coordination chemistry preferences of these two metal ions. <b>3</b> may bind two further Ag­(I) ions to the central pyridazine N, giving <b>5</b>. Treatment of <b>1</b>^<b>Br</b> with Br₂ leads to bromination at the pyrazole C⁴ of the ligand backbone, yielding [L^BrAuBr] (<b>8</b>). In contrast, <b>1</b>^<b>Cl</b> could be successfully oxidized to the Au­(III) complex [LAuCl₃] (<b>7</b>) using PhICl₂; both <b>7</b> and the gold­(I) complex <b>8</b> have been characterized crystallographically. Preliminary screening shows that <b>7</b>, in combination with AgBF₄, is a good catalyst for the etherification of 1-indanol with a variety of alcohol substrates and shows significantly higher activity than the gold­(I) catalyst <b>1</b>^<b>Cl</b>

An innovative 3-D nanoforest heterostructure made of polypyrrole coated silicon nanotrees for new high performance hybrid micro-supercapacitors

In this work, an innovative 3-D symmetric micro-supercapacitor based on polypyrrole (PPy) coated silicon nanotree (SiNTr) hybrid electrodes has been fabricated. First, SiNTrs were grown on silicon substrates by chemical vapor deposition (CVD) and then via an electrochemical method, the conducting polymer coating was deposited onto the surface of SiNTr electrodes. This study illustrates the excellent electrochemical performance of a hybrid micro-supercapacitor device using the synergistic combination of both PPy as the electroactive pseudo-capacitive material and branched SiNWs as the electric double layer capacitive material in the presence of an aprotic ionic liquid (N-methyl-N-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide; PYR13TFSI) as the electrolyte. The hybrid device exhibited a specific capacitance as high as ∼14 mF cm−2 and an energy density value of ∼15 mJ cm−2 at a wide cell voltage of 1.5 V using a high current density of 1 mA cm−2. Furthermore, a remarkable cycling stability after thousands of galvanostatic charge–discharge cycles with a loss of approximately 30% was obtained. The results reported in this investigation demonstrated that PPy coated SiNTr-based micro-supercapacitors exhibit the best performances among hybrid micro-supercapacitors made of silicon nanowire electrodes grown by CVD in terms of specific capacitance and energy density.This project has received funding from the European Union's Seventh Program for Research, Technological Development and Demonstration under Grant agreement no. 309143 (2012–2015). Dorian Gaboriau thanks the 'Délégation Générale pour l'Armament' (DGA) and the CEA for financial support.Peer Reviewe

3D hierarchical assembly of ultrathin MnO₂ nanoflakes on silicon nanowires for high performance micro-supercapacitors in Li-doped ionic liquid

Altres ajuts: Programa Beatriu de Pinós (BP-DGR-2013)Building of hierarchical core-shell hetero-structures is currently the subject of intensive research in the electrochemical field owing to its potential for making improved electrodes for high-performance micro-supercapacitors. Here we report a novel architecture design of hierarchical MnO₂@silicon nanowires (MnO₂@SiNWs) hetero-structures directly supported onto silicon wafer coupled with Li-ion doped 1-Methyl-1-propylpyrrolidinium bis(trifluromethylsulfonyl)imide (PMPyrrBTA) ionic liquids as electrolyte for micro-supercapacitors. A unique 3D mesoporous MnO₂@SiNWs in Li-ion doped IL electrolyte can be cycled reversibly across a voltage of 2.2V and exhibits a high areal capacitance of 13mFcm⁻². The high conductivity of the SiNWs arrays combined with the large surface area of ultrathin MnO₂ nanoflakes are responsible for the remarkable performance of these MnO₂@SiNWs hetero-structures which exhibit high energy density and excellent cycling stability. This combination of hybrid electrode and hybrid electrolyte opens up a novel avenue to design electrode materials for high-performance micro-supercapacitors

SiNWs-based electrochemical double layer micro-supercapacitors with wide voltage window (4V) and long cycling stability using a protic ionic liquid electrolyte

The present work reports the use and application of a novel protic ionic liquid (triethylammonium bis(tri fluoromethylsulfonyl)imide; NEtH TFSI) as an electrolyte for symmetric planar micro-supercapacitors based on silicon nanowire electrodes. The excellent performance of the device has been successfully demonstrated using cyclic voltammetry, galvanostatic charge-discharge cycles and electrochemical impedance spectroscopy. The electrochemical characterization of this system exhibits a wide operative voltage of 4 V as well as an outstanding long cycling stability after millions of galvanostatic cycles at a high current density of 2 mA cm. In addition, the electrochemical double layer micro-supercapacitor was able to deliver a high power density of 4 mWcm in a very short time pulses (a few ms). Our results could be of interest to develop prospective on-chip micro-supercapacitors using protic ionic liquids as electrolytes with high performance in terms of power and energy densities

3D hierarchical assembly of ultrathin MnO2 nanoflakes on silicon nanowires for high performance micro-supercapacitors in Li- doped ionic liquid

International audienceBuilding of hierarchical core-shell hetero-structures is currently the subject of intensive research in the electrochemical field owing to its potential for making improved electrodes for high-performance micro-supercapacitors. Here we report a novel architecture design of hierarchical MnO2@ silicon nanowires (MnO2@SiNWs) hetero-structures directly supported onto silicon wafer coupled with Li-ion doped 1-Methyl-1-propylpyrrolidinium bis(trifluromethylsulfonyl) imide (PMPyrrBTA) ionic liquids as electrolyte for micro-supercapacitors. A unique 3D mesoporous MnO2@SiNWs in Li-ion doped IL electrolyte can be cycled reversibly across a voltage of 2.2 V and exhibits a high areal capacitance of 13 mFcm(-2). The high conductivity of the SiNWs arrays combined with the large surface area of ultrathin MnO2 nanoflakes are responsible for the remarkable performance of these MnO2@SiNWs hetero-structures which exhibit high energy density and excellent cycling stability. This combination of hybrid electrode and hybrid electrolyte opens up a novel avenue to design electrode materials for high-performance micro-supercapacitors

An innovative 3-D nanoforest heterostructure made of polypyrrole coated silicon nanotrees for new high performance hybrid micro-supercapacitors

International audienceIn this work, an innovative 3-D symmetric micro-supercapacitor based on polypyrrole (PPy) coated silicon nanotree (SiNTr) hybrid electrodes has been fabricated. First, SiNTrs were grown on silicon substrates by chemical vapor deposition (CVD) and then via an electrochemical method, the conducting polymer coating was deposited onto the surface of SiNTr electrodes. This study illustrates the excellent electrochemical performance of a hybrid micro-supercapacitor device using the synergistic combination of both PPy as the electroactive pseudo-capacitive material and branched SiNWs as the electric double layer capacitive material in the presence of an aprotic ionic liquid (N-methyl-N-propylpyrrolidinium bis(trifluoromethylsulfonyl) imide; PYR13TFSI) as the electrolyte. The hybrid device exhibited a specific capacitance as high as similar to 14 mF cm(-2) and an energy density value of similar to 15 mJ cm(-2) at a wide cell voltage of 1.5 V using a high current density of 1 mA cm(-2). Furthermore, a remarkable cycling stability after thousands of galvanostatic charge-discharge cycles with a loss of approximately 30% was obtained. The results reported in this investigation demonstrated that PPy coated SiNTr-based micro-supercapacitors exhibit the best performances among hybrid micro-supercapacitors made of silicon nanowire electrodes grown by CVD in terms of specific capacitance and energy density