Search

A free-standing Si@Co 9 S 8 CF electrode with excellent rate capability and cycling performance was obtained by electrospinning, vulcanization, and carbonization processes as high-performance anode for Li-ion batteries. [Display omitted] • Si@Co 9 S 8 CF films are explored by electrospinning, vulcanization and carbonization. • The yolk-shelled Si@Co 9 S 8 can remarkably alleviate the volume expansion. • The introduction of CFs can improve the electrical conductivity of the electrodes. • The free-standing anode avoids the conventional process of electrode preparation. Silicon-based (Si-based) materials have aroused extensive attention owing to their ultra-high theoretical specific capacity, while the huge volume expansion and inferior electronic conductivity have impeded their practical application in lithium-ion batteries (LIBs). Rational structural design has been regarded as a fascinating strategy, especially for yolk-shell structures. Herein, Si nanoparticles (Si NPs) were encapsulated in ZIF-67 metal–organic frameworks to obtain Si@ZIF-67 particles, which were wrapped in one-dimensional carbon fibers (CFs) by simple processes of electrospinning, vulcanization and carbonization to obtain a free-standing Si@Co 9 S 8 CF electrode. The yolk-shelled Si@Co 9 S 8 particles could remarkably ameliorate the volume variation of Si materials during the lithiation/de-lithiation cycling and the introduction of CFs endowed an efficient one-dimensional electronic pathway accurately to improve the conductivity of composite materials. In addition, it was not negligible that the as-obtained Si@Co 9 S 8 CF films could be as a self-supporting electrode, which avoided the traditional cumbersome procedure of the electrode preparation. The resulting composite electrodes possess an excellent rate performance and an ultra-stable cycling lifespan. We hope this work can provide some novel insights for the development of the self-supporting Si-based electrode materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ti 3 C 2 T x /g-C 3 N 4 flexible free-standing electrode was prepared and show excellent performance. • Flexible solid-state supercapacitors were assembled and can work stably even in the 180° bending state. • DFT calculation was performed to reveal the mechanism of enhanced electrochemical performance of Ti 3 C 2 T x /g-C 3 N 4 heterostructure. With the popularity of intelligent portable electronic devices, bendable and flexible electronic equipment, such as portable miniature devices, wearable electronics, smart clothing, electronics, display, skin flexible smartphones and implantable medical devices have become a development trend. As potential energy storage device, flexible supercapacitors have attracted extensive attention. Ti 3 C 2 T x MXenes, which has high capacitance, mechanical strength and flexibility, perfectly meets the requirements of flexible energy storage devices. In order to avoid stacking, increase layer spacing, and enhance charge transfer efficiency, the Ti 3 C 2 T x /g-C 3 N 4 heterostructure is constructed by self-assembly method. The flexible self-supporting electrode is prepared by vacuum assisted filtration, which successfully widen the potential window and significantly improve the capacitance performance. The specific capacitance of the electrode in 1 M H 2 SO 4 electrolyte reaches 414 F/g at 1A/g. The electrode can simultaneously act as a fluid collector to construct a simple ultra-thin device. The flexible all-solid symmetric supercapacitor is assembled and the energy density reaches 23.98 Wh/Kg when the power density is 139.66 W/Kg. Encouragingly, the device can maintain stable performance under 180° bending conditions. The above excellent performance confirms the applicability of supercapacitors based on Ti 3 C 2 T x /g-C 3 N 4 heterostructure films for future portable, flexible or wearable electronic energy storage devices. [ABSTRACT FROM AUTHOR]

A high-performance flexible Zn-ion hybrid supercapacitor was fabricated by an adjustable structural optimization, and the potential practical value of the flexible all-solid-state hybrid supercapacitor was demonstrated. [Display omitted] • A zinc-ion hybrid supercapacitor derived from biomass carbon is fabricated. • The supercapacitor exhibits desirable flexibility and long cycling stability. • The remarkable performance is related to structural design. • A typical FZHSC device shows the potential practical application. The demand for developing sustainable energy storage renders biomass-based electrode materials a timely and important goal. However, the desirable electrochemical performance of the supercapacitor has still been hindered by insufficient contact chance between the active material and the electrolyte when both energy density and power density are required. Herein, the porous bamboo carbons were managed and used as the cathode to construct a flexible and high-performance Zn-ion hybrid supercapacitor (ZHSC) by combining the merit of capacitor-type and battery-type electrode materials. The porous material with high porosity is obtained via a controllable structural optimization. Consequently, the as-constructed hybrid supercapacitor delivers a superior specific capacitance of 321.3F g−1 at 1 A g−1 together with a high energy density of 114.2 Wh kg−1 when the power density is 800.0 W kg−1. Meanwhile, the assembled flexible hybrid supercapacitor displays remarkable cycling stability with 78% capacitance retention after 20,000 cycles and enough to suffer various deformations with no noticeable degradation of capacitance. Finally, the potential practical value of the flexible hybrid supercapacitor is demonstrated by an eye-catching orbital diagram. This work reveals that the flexible supercapacitor mainly constructed by porous biomass carbon is a promising candidate for energy storage devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • The partly crosslinked polymer electrolyte presents a maximum conductivity of 1× 10−4 S·cm−1 at 30 °C and wide electrochemical window. • The LiFePO 4 ||Li cell exhibits excellent capacity retention of 91% after 100 cycles. • Satisfactory stability for NCM811||Li high-voltage lithium batteries. The Ti3+ doped TiO 2 nanowires were grafted by tolylene-2,4- diisocyanate (TDI) and applied as a modifier for the preparation of organic–inorganic hybrid electrolyte in high performing lithium batteries. The PEO-based polymer electrolyte was optimized at different organic–inorganic ratios and exhibited excellent lithium-ion conductivity of 1 × 10−4 S·cm−1 at 30 °C when adding 8% TDI-TiO 2 nanowires, outstanding electrochemical stability with a wide electrochemical window up to 5.5 V at 60 °C and a high lithium-ion transport number of 0.36. The LiFePO 4 |PTTNW8%|Li cells deliver excellent rate capability and cycling performance, with a high initial discharge capacity up to 151 mAh·g−1 at 60 °C at 0.1 C rate and excellent capacity retention of 91% after 100th cycle. NCM811|PTTNW8%|Li high-voltage lithium batteries were also demonstrated at a 50 °C, which displayed a superior cycling performance. Therefore, the prepared PEO-TDI-TiO 2 electrolyte is a promising polymer electrolyte for solid- state lithium batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • The highlights of this work are as follows: • N-doped biochar derived from squid ink is premiere application for electrospinning. • Biochar composite with high-capacity used in flexible asymmetric supercapacitor. • The regulation of temperature and KOH content reveal the energy storage mechanism. Flexible supercapacitors have become a concern of flexible energy storage devices. In the process of exploring, the squid ink as N-doped biomass carbon was introduced to self-supporting flexible supercapacitors by electrospinning for the first time. By regulating the content of squid ink, the activation temperature, and the mass ratio of KOH-assisted activation, a N-doped porous biomass carbon@polyacrylonitrile (NPBC-1.5@PAN-800-2) with an ideal capacity and an excellent specific surface area (636.68 m2 g−1) was prepared. In addition, ZnO further optimized the capacity (422.7 F/g at 1 A g−1) and as an adhesive-free electrode for flexible asymmetric supercapacitor provided a relatively high specific capacitance, a satisfactory capacitance retention, and a wonderful energy density (48.01 Wh kg−1 at 1124.43 W kg−1). The capacitance was thought to originate from a suitable microporous structure, N-doped, and metal-derived pseudocapacitance propertie. [ABSTRACT FROM AUTHOR]

The synergistic effect of sodium and oxygen expands π-conjugated aromatic rings and distortion of the heptazine skeleton, enhancing the intrinsic π→π* electron transition and the effective n→π* electron transition. [Display omitted] • A sodium and oxygen co-doped g-C 3 N 4 (NaOCN) is prepared by facile microwave synthesis, in which Na as a charge transport channel promotes the separation efficiency of photogenerated carriers. • The as-prepared NaOCN exhibits the NIR absorption extended to 1400 nm and the apparent quantum yield (AQY) can keep 26.9% at 420 nm and still maintain 7.2 % at 600 nm, which shows strong NIR response range. • The intrinsic π → π* electron transition and active the n → π* electron transition generated by the synergistic effect of Na and O atoms are the main factor to promote the NIR response of NaOCN. Efficient utilization of near-infrared light (NIR) is critical to optimize the performance of photocatalysts. Herein, an ultrafast process is employed to co-condensation of melamine and NaCl by microwave-assist heating. The fabricated sodium and oxygen co-doped g-C 3 N 4 (NaOCN) shows extended π-conjugated aromatic rings and distortion of the heptazine skeleton, which can enhance the intrinsic π → π* electron transition and active the n → π* electron transition. The robust n → π* excitation of NaOCN leads to a narrowed bandgap of 2.73 eV with the NIR absorption extending to 1400 nm. The apparent quantum yield (AQY) for NaOCN can still keep 7.2 % at 600 nm. This work provides a promising way for the application of NIR-based carbon nitride in photocatalytic H 2 O 2 production. [ABSTRACT FROM AUTHOR]

A morphology-controllable 0D/1D g-C 3 N 4 (CN) homojunction using the melamine-cyanuric acid supramolecular (MCS) and urea as co-precursor was constructed by a facile in-situ thermal polymerization process. [Display omitted] • A morphology-controllable 0D/1D g-C 3 N 4 homojunction (MUCN) was constructed by a facile in-situ thermal polymerization process. • The as-prepare MUCN is stable with controllable and uniform morphology and exhibits significantly enhanced photocatalytic activities for RhB degradation and H 2 O 2 production. • The significantly enhanced photocatalytic performance of MUCN is attributed to the synergetic effect of energy band controlling and structural coupling in MUCN. • The results have provided a new effective way for promoting the practical photocatalytic application of CN. A morphology-controllable 0D/1D graphitic carbon nitride (g-C 3 N 4 , CN) homojunction (MUCN) was constructed by a facile in-situ thermal polymerization process using the melamine-cyanuric acid supramolecular (MCS) and urea as co-precursor. The as-prepare MUCN is stable with controllable and uniform morphology and exhibits significantly enhanced photocatalytic activities for RhB degradation and H 2 O 2 production. The RhB degradation rate and the H 2 O 2 production are ~37 times and 17 times higher than that of pure CN, respectively. The significantly enhanced photocatalytic performance is attributed to the synergetic effect of energy band controlling and structural coupling in MUCN, which can form the internal driving force to improve the separation efficiency of charge carriers. The results have provided a new effective way for promoting the practical photocatalytic application of CN. [ABSTRACT FROM AUTHOR]