Flexible Asymmetric Threadlike Supercapacitors Based on NiCo₂Se₄ Nanosheet and NiCo₂O₄/Polypyrrole Electrodes

Abstract

Flexible threadlike supercapacitors with improved performance are needed for many wearable electronics applications. Here, we report a high performance flexible asymmetric all-solid-state threadlike supercapacitor with a NiCo Se positive electrode and a NiCo O @PPy (PPy: polypyrrole) negative electrode. The as-prepared electrodes display outstanding volume specific capacitance (14.2 F cm ) and excellent cycling performance (94 % retention after 5000 cycles at 0.6 mA) owing to their nanosheet and nanosphere structures. The asymmetric all-solid-state threadlike supercapacitor expanded the stability voltage window from 0-1.0 V to 0-1.7 V and exhibits high volume energy density (5.18 mWh cm ) and superior flexibility under different bending conditions. This study provides a scalable method for fabricating high performance flexible supercapacitors from easily available materials for use in wearable and portable electronics.

Combined High Catalytic Activity and Efficient Polar Tubular Nanostructure in Urchin‐Like Metallic NiCo2Se4 for High‐Performance Lithium–Sulfur Batteries

“…Similarly, in the Co 2p spectra (Figure S3b, Supporting Information), the peaks located at 778.9 eV (Co 2p 3/2 ) and 793.9 eV (Co 2p 1/2 ) are related to Co 3+ and those at 781.2 eV (Co 2p 3/2 ) and 797.5 eV (Co 2p 1/2 ) to Co 2+ . Se 3d peaks are located at 59.3 (Se 3d 3/2 ) and 54.8 eV (Se 3d 5/2 ) in agreement with Se 2− in a metal selenide environment (Figure S3c, Supporting Information) . The XPS spectra show the presence of occupied states at the Fermi level as it corresponds to a metal or a highly degenerated semiconductor (Figure S3d, Supporting Information).…”

NiCo2Se4 Hierarchical Microflowers of Nanosheets and Nanorods as Pseudocapacitive Mg-Storage Materials

“…NiCo 2 Se 4 , as a ternary Ni/Co selenide, has been reported to be applied to supercapacitors and electrocatalysis. − For instance, Miao et al used NiCo 2 Se 4 nanosheets to improve the performance of flexible threadlike supercapacitors, which exhibits 5.18 mW h cm –3 high volume energy density . Hollow NiCo 2 Se 4 microspheres could also be employed for highly efficient water splitting .…”

Facile one-pot synthesis of NiCo2Se4-rGO on Ni foam for high performance hybrid supercapacitors

“…The charge storage of NiCo 2 Se 4 -rGO@NF can be attributed to the redox reaction between Ni 2+ /Ni 3+ , Co 3+ /Co 4+ , and Co 2+ /Co 3+ . 57,58 NiCo 2 Se 4 crystallizes in a spinel structure type where divalent Ni occupies the tetrahedral sites whereas, trivalent Co occupies the vacancy ordered octahedral layers. However, scrambling of the metal ions between the octahedral and tetrahedral sites has been observed quite frequently in these spinel compounds, leading to presence of mixed oxidation states such as Ni 2+ /Ni 3+ and Co 2+ /Co 3+ .…”