Ammonia strengthened graphene/CNT-wrapped polyaniline-nanofiber composites loaded with palladium nanoparticles for coin cell supercapacitors

Construction of ultra-stable trinickel disulphide (Ni3S2)/polyaniline (PANI) electrodes based on carbon fibers for high performance flexible asymmetric supercapacitors

Highly flexible supercapacitors (SCs) have attracted significant attention in modern electronics. However, it has been found that flexible, metal sulfide-based electrodes usually suffer from corrosion, instability and low conductivity, which significantly limits their large scale application. Herein, we report on an electrode comprised of highly stable, free-standing carbon fiber/trinickel disulphide covered with polyaniline (CF/Ni₃S₂@PANI). This electrode was prepared and then employed in a high-performance of flexible asymmetric SCs (FASC). The coating layer of polyaniline served as both a protector and conducting shell for the Ni₃S₂ due to the nature of the highly stable N-Ni bonds that formed between the polyaniline and Ni₃S₂. In addition, the lightweight carbon fiber support served as both a current collector and flexible support. The prepared CF/Ni₃S₂@PANI electrode exhibited a significantly enhanced specific capacity (715.3 F·g^-1 at 1 A·g^-1) compared with the carbon fiber/Ni₃S₂ electrode (318 F·g^-1 at 1 A·g^-1). More importantly, the assembled FASC device delivered an impressive energy density of 35.7 Wh·kg^-1 at a power density of 850 W·kg^-1. The FASC device benefited from the interconnected flexible microstructure and the stable bond bridges, so that it could be bent into various angles without noticeably impairing its performance. This effective protective strategy may further inspire the design and manufacture of metallic oxide or sulfide electrode with ultrahigh-stability interbond bridges for high-performance flexible supercapacitors.

Ex Situ Fabrication of Polypyrrole-Coated Core-Shell Nanoparticles for High-Performance Coin Cell Supercapacitor

Silica-conducting polymer (SiO₂-CP) has the advantages of high electrical conductivity, structural stability, and the facile formation of thin-film. This work deals with the preparation and optimization of polypyrrole (PPy)-encapsulated silica nanoparticles (SiO₂ NPs) using an ex situ method. The SiO₂-PPy core-shell NPs prepared by the ex situ method are well dispersed in water and facilitate the mass production of thin-film electrodes with improved electrical and electrochemical performances using a simple solution process. As-prepared SiO₂-PPy core-shell NPs with different particle sizes were applied to electrode materials for two-electrode supercapacitors based on coin cell batteries. It was confirmed that the areal capacitance (73.1 mF/cm²), volumetric capacitance (243.5 F/cm³), and cycling stability (88.9% after 5000 cycles) of the coin cell employing the ex situ core-shell was superior to that of the conventional core-shell (4.2 mF/cm², 14.2 mF/cm³, and 82.2%). Considering these facts, the ex situ method provides a facile way to produce highly-conductive thin-film electrodes with enhanced electrical and electrochemical properties for the coin cell supercapacitor application.