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

Abstract

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

Asymmetric Supercapacitors Based on Reduced Graphene Oxide with Different Polyoxometalates as Positive and Negative Electrodes

“…Ideal capacitive behavior of an electrode can be estimated from the frequency ( f 0 ) at which the phase angle crosses 45° angle . For example, commercial activated‐carbon‐based EDLCs show a 45° phase angle at approximately 0.2 Hz . Herein, the rGO‐PMo 12 ∥rGO‐PW 12 cell shows a phase angle of 45° at approximately 5.24 Hz (relaxation time constant τ 0 =0.19 s), suggesting a rapid frequency response and excellent capacitive behavior.…”

“…[28] For example, commercial activated-carbon-based EDLCs showa458 phase angle at approximately 0.2 Hz. [29] Herein, the rGO-PMo 12 k rGO-PW 12 cell shows ap hase angle of 458 at approximately 5.24 Hz (relaxation time constant t 0 = 0.19 s), suggesting ar apid frequencyr esponse and excellent capacitive behavior. Thee lectrochemical performance of the cell can also be evaluated by calculating the real and imaginary capacitances at corresponding frequencies [Eq.…”

New electrolyte mixture of propylene carbonate and butyltrimethylammonium bis(trifluoromethylsulfonyl)imide (N1114 TFSI) for high performance silicon nanowire (SiNW)-based supercapacitor applications

“…These values were compared to the state-of-the-art using similar studies dealing with silicon nanostructures such as CVD-SiNWs [1,[4][5][6]8,21], silicon nanotrees (SiNTrs) [15] or silicon carbide nanowires (SiCNWs) [34] in presence of various electrolytes. Additionally, a comparison with other micro-supercapacitors based on the functionalization of CVD-SiNWs by using pseudocapacitive materials such as electroactive conducting polymers (PEDOT and PPy) [35,36] or transition metal oxides (MnO 2 ) [37] has been also reported. In this direction, as expected according to the working principle of pseudocapacitors, energy density (2.5 À 5 mWhcm À2 ) was found to be higher than the results reported in this study, whereas the power density (0.6 À 1Á10 3 mWcm À2 ) was lower compared to pure SiNW EDLCs (> 2Á10 3 mWcm À2 ) [16].…”

Stretchable Supercapacitors as Emergent Energy Storage Units for Health Monitoring Bioelectronics

“…[145] Choosing suitable method is vital for the practical designs of planar supercapacitors. [146] To further increase the mass loading and power density, layer-by-layer deposition was adopted, which allows the deposition of compact films that are permeable to ions. Normally, sputtering is utilized in deposition of gold current collectors associated with micromasking technique.…”