Advanced Carbon–Nickel Sulfide Hybrid Nanostructures: Extending the Limits of Battery-Type Electrodes for Redox-Based Supercapacitor Applications

• Published in: ACS applied materials & interfaces 2021-05, Vol.13 (17), p.20559-20572
• Main Authors: Santhosh, Neelakandan M, Upadhyay, Kush K, Stražar, Petra, Filipič, Gregor, Zavašnik, Janez, Mão de Ferro, André, Silva, Rui Pedro, Tatarova, Elena, Montemor, Maria de Fátima, Cvelbar, Uroš
• Format: Article
• Language: English
• Subjects: Functional Nanostructured Materials (including low-D carbon)
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.1c03053

Transition-metal sulfides combined with conductive carbon nanostructures are considered promising electrode materials for redox-based supercapacitors due to their high specific capacity. However, the low rate capability of these electrodes, still considered “battery-type” electrodes, presents an obstacle for general use. In this work, we demonstrate a successful and fast fabrication process of metal sulfide–carbon nanostructures ideal for charge-storage electrodes with ultra-high capacity and outstanding rate capability. The novel hybrid binder-free electrode material consists of a vertically aligned carbon nanotube (VCN), terminated by a nanosized single-crystal metallic Ni grain; Ni is covered by a nickel nitride (Ni3N) interlayer and topped by trinickel disulfide (Ni3S2, heazlewoodite). Thus, the electrode is formed by a Ni3S2/Ni3N/Ni@NVCN architecture with a unique broccoli-like morphology. Electrochemical measurements show that these hybrid binder-free electrodes exhibit one of the best electrochemical performances compared to the other reported Ni3S2-based electrodes, evidencing an ultra-high specific capacity (856.3 C g–1 at 3 A g–1), outstanding rate capability (77.2% retention at 13 A g–1), and excellent cycling stability (83% retention after 4000 cycles at 13 A g–1). The remarkable electrochemical performance of the binder-free Ni3S2/Ni3N/Ni@NVCN electrodes is a significant step forward, improving rate capability and capacity for redox-based supercapacitor applications.