Porous Co₉S₈ Nanosheet Arrays@Co Foam Electrode via in Situ Sulfidation at Room Temperature for Superior Supercapacitors

Abstract

In this work, novel porous Co9S8 nanosheet arrays are prepared on Co foam through a simple and scalable chemical liquid-phase processing strategy, which involves the uniform growth of cobalt hydroxide hydrogen phosphate microbelts followed by subsequent in situ sulfidation with sodium sulfide at room temperature. As-prepared porous Co9S8 nanosheet arrays can be directly used as binderless electrodes for a supercapacitor. Even at a high mass loading of 11.54 mg cm–2, it delivers a high capacitance of 14518.9 mF cm–2 (1279.4 F g–1) and an exceptional cycle life with a capacitance retention of 85.7% after 15000 cycles at 200 mA cm–2. Moreover, an assembled asymmetric supercapacitor based on an activated carbon negative electrode delivers an encouraging energy density (42.9 W h kg–1 at 828.5 W kg–1) and an excellent cycle life (86% retention after 10000 cycles). This method can be extended to design and construct other high-performance sulfide electrodes for supercapacitors and other energy storage systems.

Facile synthesis of mesoporous NixCo9−xS8 hollow spheres for high-performance supercapacitors and aqueous Ni/Co–Zn batteries

“…The capacity of Ni-Co 9 S 8 -0.6 electrode attenuate to 74.5% after 5000 repeated cycles. More importantly, the mesoporous hollow Ni-Co 9 S 8 -0.6 electrode exhibited a performance comparable to or higher than the recently reported sulfide-related electrodes such as rGO/Co 9 S 8 (575.9 F g −1 , 2 A g −1 ), 36 CoNi 2 S 4 /Co 9 S 8 composites (1183.3 F g −1 , 2 A g −1 ), 37 Ni 3 S 4 @Co 9 S 8 tubes (1002.2 F g −1 , 1 A g −1 ), 38 CoO/Co 9 S 8 hollow microspheres (1100 F g −1 , 2 A g −1 ), 39 GH@NC@Co 9 S 8 composite (540 F g −1 , 1 A g −1 ), 40 Co 9 S 8 nanowire/Ni (1191.17 F g −1 , 2 mV s −1 ), 41 0.3 cP/rGO/Co 9 S 8 (788.9 F g −1 , 1 A g −1 ), 42 Co 9 S 8 @N-C@MoS 2 (410 F g −1 , 10 A g −1 ), 43 Co 3 (OH) 2 (HPO 4 ) 2 @Co 9 S 8 /Co electrode (1279.4 F g −1 , 5 mA cm −2 ), 44 CoS@NSC-800 (289 F g −1 , 1 A g −1 ), 45 Co 9 S 8 @NiCo 2 S 4 @NF electrode (1026 F g −1 , 1 A g −1 ), 46 (Co 0.94 Fe 0.06 ) 9 S 8 hollow spheres (454 F g −1 , 1 A g −1 ), 47 Co 9 S 8 -2@CN/NF (471.1 F g −1 , 0.5 A g −1 ), 48 Co 9 S 8 –aCNT–NiCoLDH (1185.5 F g −1 , 1 A g −1 ), 49 and MnCo 2 S 4 /Co 9 S 8 /Ni composites (1058.0 F g −1 , 1 A g −1 ). 50 A more extensive comparison of super-capacitance performance of Ni-Co 9 S 8 -0.6 with other related electrodes are listed in Table S2 †.…”

Construction of Hierarchical Mn2O3@MnO2 Core–Shell Nanofibers for Enhanced Performance Supercapacitor Electrodes

“…Electric double-layer capacitors (EDLCs) can store charges through the reversible ion adsorption and desorption at the electrode/electrolyte interface of carbon-active materials, and pseudocapacitors (PCs) store charge by fast faradaic oxidation/reduction reactions of transition metal oxides/sulfides and conducting polymers. In comparison with EDLCs, PCs deliver an exceptional specific capacitance and energy density. − Among the widely explored PC electrode materials, manganese oxides (MnO x ) have received a lot of interest due to their merits of large theoretical capacity, reversible charge–discharge characteristics, natural abundance, and low cost. − Until now, a wide variety of nanostructured MnO x -based SC electrode materials such as nanocubes, , nanospheres, , nanobelts, nanobowls, nanowalls, , nanosheets, − and nanowires , have been successfully synthesized through a wide range of strategies. Recently, Alshareef and co-workers prepared MnO 2 nanoparticles with controllable structure and oxygen vacancy concentration through a rational design coprecipitation strategy, and the as-fabricated MnO 2 NP electrodes exhibited an improved capacitance of 202 F g –1 at 1 A g –1 .…”

Molecule-assisted modulation of the high-valence Co3+ in 3D honeycomb-like CoxSy networks for high-performance solid-state asymmetric supercapacitors

“…Meanwhile, the construction of three-dimensional (3D) porous structures is an effective strategy to accelerate the reaction kinetics and improve the energy storage performance of electrode materials [20]. In particular, those 3D cross-linked nanosheet arrays grown on current collectors can not only shorten the ion diffusion paths, but also reduce the charge-transfer resistance, provide abundant active sites and enough holes to accommodate the volume expansion, which together benefit the rate and cycling performance [21][22][23][24]. However, the rational construction of 3D structures with cross-linked nanosheet arrays is still a challenge.…”

“…Among the numerous strategies proposed, metal-organic framework (MOF) self-templating method has been emerged as an especially fascinating approach. MOFs are a combination of metal ions and organic ligands with ordered tunnels [22,25], and the MOF-derived materials can maintain the architectures of pristine MOFs, achieving well-organized and customizable structures, adjustable pores and large specific surface areas [26]. In addition, the metal ions can be effectively confined by the organic frameworks, which can be further transformed to transition metal-based derivatives [12].…”