Mosaic-Structured SnO 2 @C Porous Microspheres for High-Performance Supercapacitor Electrode Materials

Composite Assembling of Oxide-Based Optically Transparent Electrodes for High-Performance Asymmetric Supercapacitors

Simultaneously achieving a transparent and high-energy density supercapacitor is a major challenge because of the trade-off between energy storage capacity and optical transparency of active electrode materials. Herein, we demonstrate a novel approach to construct an optically transparent asymmetric supercapacitor (Trans-ASC) by assembling positive (ZnO-SnO2) and negative (TiO2-SnO2) composite thin-film electrodes on a conductive indium-doped tin oxide substrate via reactive DC magnetron cosputtering. The optical transmittance for both composite thin films is found to be 68% (ZnO-SnO2) and 64% (TiO2-SnO2). Furthermore, electrochemical kinematics of the primed transparent electrodes are scrutinized in 0.5 M KOH electrolyte without affecting the transparency of active electrodes. The structural reliability of the electrodes aids the superb electrochemical performance to construct a Trans-ASC, TiO2-SnO2//ZnO-SnO2, which works at a voltage of +1.2 V and attains a higher areal capacitance of 44.6 mF cm-2 at 2 mA cm-2. The assembled Trans-ASC delivers a maximum areal energy density of 8.75 μW h cm-2 with an optimal areal power density of 570 μW cm-2. Additionally, the capacitance retention of 81.6% and transparency of both electrodes remain almost the same (up to 60% for ZnO-SnO2 and 62% for TiO2-SnO2) even after 10,000 charging-discharging cycles. These remarkable electrochemical properties and outstanding cycling stability of the designed Trans-ASC device make it a potential candidate for storing energy and for further use in transparent electronic devices.

Tin-based metal-phosphine complexes nanoparticles as long-cycle life electrodes for high-performance hybrid supercapacitors

New tin-based metal-phosphine complexes of [Sn(OH)₄(PPh₃)₂] and [Sn(OH)₂(PPh₃)₂] have been successfully synthesized and used as supercapacitor electrodes for the first time, exhibiting a high specific capacitance, a good rate capability, and an excellent cycling stability. The specific capacitances (highest specific capacitance for tin-based materials) of 1204F g^-1 and 764F g^-1 for two samples at a current density of 1 A g^-1 in 6 M KOH can respectively be achieved, and their capacitance retention remained at 95.1% and 89.2% even after 15,000 cycles at a current density of 10 A g^-1. Furthermore, a flexible quasi-solid-state asymmetric supercapacitor composed of Sn(OH)₂(PPh₃)₂ and activated carbon was assembled and exhibited a specific capacitance of 290.6 mF cm^-2 at a current density of 1 mA cm^-2. More importantly, this device also displayed excellent cyclic stability of ∼100% for 1800 cycles during the galvanostatic charge/discharge process at 5 mF cm^-2.

Decoration of mesoporous carbon electrodes with tin oxide to boost their supercapacitive performance

A unique material comprising mesoporous carbon decorated with tin oxide was synthesised by facile incipient wetness impregnation for enhanced charge storage.

Porous, flexible, and core-shell structured carbon nanofibers hybridized by tin oxide nanoparticles for efficient carbon dioxide capture

HYPOTHESIS

Carbon based nanofibrous materials are considered to be promising sorbents for the CO₂ capture and storage. However, the precise control of porous structure with flexibility still remains a challenging task. In this research, we report a simple strategy to develop tin oxide (SnO₂) embedded, flexible and highly porous core-shell structured carbon nanofibers (CNFs) derived from polyacrylonitrile (PAN)/polyvinylidene fluoride (PVDF) core-shell nanofibers.

EXPERIMENT

PAN/PVDF core-shell solutions were electrospun using co-axial electrospinning process. The as spun PAN core, and PVDF shell, with an appropriate amount of SnO₂, fibers were stabilized followed by carbonization to develop SnO₂ embedded highly porous and flexible core-shell structured CNFs.

FINDINGS

The optimized CNFs membrane shows a prominent CO₂ capture capacity of 2.6 mmol g^-1 at room temperature, excellent CO₂ selectivity than N₂, and a remarkable cyclic stability. After 20 adsorption-desorption cycles, the CO₂ capture capacity retains >95% of the preliminary value showing the long-term stability and practical worth of the final product. The loading of SnO₂ nanoparticles in the carbon matrix not only enhanced the thermal stability of the precursor nanofibers, their surface characteristics, and porous structure to capture CO₂ molecules, but also improves the flexibility of the CNFs by serving as a plasticizer for single-fiber-crack connection. Meaningfully, the flexible SnO₂ embedded core-shell CNFs with excellent structural stability can prevail the limitations of annihilation and collapse of structures for conventional adsorbents, which makes them strongly useful and applicable. This research introduces a new route to produce highly porous and flexible materials as solid adsorbents for CO₂ capture.

Porous materials of nitrogen doped graphene oxide@SnO2 electrode for capable supercapacitor application

The porous materials of SnO₂@NGO composite was synthesized by thermal reduction process at 550 °C in presence ammonia and urea as catalyst. In this process, the higher electrostatic attraction between the SnO₂@NGO nanoparticles were anchored via thermal reduction reaction. These synthesized SnO₂@ NGO composites were confirmed by Raman, XRD, XPS, HR-TEM, and EDX results. The SnO₂ nanoparticles were anchored in the NGO composite in the controlled nanometer scale proved by FE-TEM and BET analysis. The SnO₂@NGO composite was used to study the electrochemical properties of CV, GCD, and EIS analysis for supercapacitor application. The electrochemical properties of SnO₂@NGO exhibited the specific capacitance (~378 F/g at a current density of 4 A/g) and increasing the cycle stability up to 5000 cycles. Therefore, the electrochemical results of SnO₂@NGO composite could be promising for high-performance supercapacitor applications.

High-Performance On-Chip Supercapacitors Based on Mesoporous Silicon Coated with Ultrathin Atomic Layer-Deposited In2O3 Films

On-chip supercapacitors have attracted considerable attention because of their high power density, long cycling life, and compatibility with integrated circuits. One critical drawback that restricts their practical application is the low energy density. In this work, low-resistivity mesoporous silicon with a high aspect ratio is prepared by Pt film-assisted chemical etching and utilized as the scaffold of the supercapacitors. Subsequently, low-resistivity (<0.0015 Ω·cm) and ultrathin In₂O₃ films are coated on the mesoporous silicon scaffold by atomic layer deposition at 200 °C, serving as the active electrode material. The electrochemical measurements reveal that the coating of the In₂O₃ film remarkably improves the performance of the supercapacitors compared with those without the In₂O₃ coating. The supercapacitors with a 4.5 nm In₂O₃ film coating exhibit a capacitance density of 1.36 mF/cm² at a scan rate of 10 mV/s as well as a better stability against the scan rate. In addition, it is found that the pristine mesoporous silicon walls are collapsed after 400 times of sweeping while those with the In₂O₃ film coating are still intact even after 2000 times of sweeping. Meanwhile, a high energy density is also achieved without sacrificing the power performance.

Applications of hierarchically structured porous materials from energy storage and conversion, catalysis, photocatalysis, adsorption, separation, and sensing to biomedicine

A comprehensive review of the recent progress in the applications of hierarchically structured porous materials is given.

Three-dimensional graphene-wrapped PANI nanofiber composite as electrode material for supercapacitors

A novel method to prepare three-dimensional graphene-wrapped PANI nanofiber composite with high supercapacitive performance is supplied in this work.