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

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

Diamond-coated silicon nanowires for enhanced micro-supercapacitor with ionic liquids

Silicon nanowires (SiNWs) and diamond-coated SiNWs (D@SiNWs) on highly n-doped silicon wafer substrates were prepared through standard chemical vapor deposition (CVD) method as electrodes for micro-supercapacitors. The surface of electrodes exhibited uniform distribution of SiNWs on silicon wafer and continuous diamond coating on SiNWs. Electrochemical measurements were carried out in order to test the combined effect of using Ionic Liquid electrolytes and diamond coating on SiNWs on energy storage performance. Optimal values of areal capacitance, energy density and power densities were 317 μF cm-2, 0.13 μWh cm-2 and 150 μW cm-2, respectively. So, the work reported here confirms the suitability and compatibility of D@SiNWs electrode materials and ionic liquid electrolytes for the fabrication of high-performing and robust micro-supercapacitors

Gold and palladium hetero-bis-NHC complexes: Characterizations, correlations, and ligand redistributions

10.1021/om400313rOrganometallics32133685-3696ORGN