Vital effect of sufficient vulcanization on the properties of Ni-Co-S/graphene composites for supercapacitor

Achieving Ultrahigh Energy-Density Aqueous Supercapacitors via a Novel Acidic Radical Adsorption Capacity-Activation Mechanism in Ni(SeO3 )/Metal Sulfide Heterostructure

Transitional metal chalcogenide (TMC) is considered as one promising high-capacity electrode material for asymmetric supercapacitors. More evidence indicates that TMCs have the same charge storage mechanism as hydroxides, but the reason why TMC electrode materials always provide higher capacity is rare to insight. In this work, a Ni_x Co_y Mn_z S/Ni(SeO₃ ) (NCMS/NSeO) heterostructure is prepared on Ni-plated carbon cloth, validating that both NCMS and NSeO can be transformed into hydroxides in electrochemical process as accompanying with the formation of SeO₃ ^2- and SO_x ^2- in confined spaces of NCMS/NSeO/Ni sandwich structure. Based on density functional theory calculation and experimental results, a novel space-confined acidic radical adsorption capacity-activation mechanism is proposed for the first time, which can nicely explain the capacity enhancement of NCMS/NSeO electrode materials. Thanks to the unique capacity enhancement mechanism and stable NCMS/NSeO/Ni sandwich structure, the optimized electrodes exhibit a high capacity of 536 mAh g^-1 at 1 A g^-1 and the impressive rate capability of 140.5 mAh g^-1 at the amazing current density of 200 A g^-1 . The assembled asymmetric supercapacitor achieves an ultrahigh energy density of 141 Wh Kg^-1 and an impressive high-rate capability and cyclability combination with 124% capacitance retention after 10 000 cycles at a large current density of 50 A g^-1 .

Uniform Bi-Bi2O3 nanoparticles/reduced graphene oxide composites for high-performance aqueous alkaline batteries

Aqueous alkaline batteries (AABs) with the merits of both high energy density and power density have emerged as one of the most promising candidates for the new generation of energy storage devices, while their practical applications are still limited by the lack of high-performance electrode materials, especially for the anode materials. Herein, metallic bismuth-bismuth oxide nanoparticles (Bi-Bi₂O₃), with numerous heterogeneous interfaces, are successfully anchored and uniformly distributed on reduced graphene oxide (rGO) sheets. When Bi-Bi₂O₃/rGO-20 electrode is used as the anode material for an AAB, it shows a high specific capacity of 288.0 mA h g^-1 (1036.9 F g^-1) at 1 A g^-1 and good rate capability (74.7% of capacity retention ratio at 20 A g^-1). Additionally, in order to match well with a Bi-Bi₂O₃/rGO-20 anode, CoVS_x thin sheets decorated with Ni-Co layered double hydroxide sheets (NiCo-LDH) were successfully constructed via a facile multistep hydrothermal method and a subsequent electrodeposition process. The resulting cathode exhibits a high specific capacity of 306.0 mA h g^-1 (2448 F g^-1) at 1 A g^-1. The assembled CoVS_x@NiCo-LDH//Bi-Bi₂O₃/rGO-20 AAB delivers an outstanding energy density of 106.1 Wh kg^-1 at a power density of 789.6 W kg^-1. Besides, the as-synthesized Bi-based electrode is also used in aqueous Zn alkaline batteries to further extend its application and the assembled Bi-Bi₂O₃/rGO-20//Zn batteries possess an ultralong flat discharge plateau and exhibit a specific capacity of 250.6 mA h g^-1 at 1 A g^-1. The results demonstrate that the as-assembled AAB has huge potential for practical applications and provides an inspiration for the next-generation energy storage devices.

Electrodeposited cobalt sulfide on a vertical graphene nanocomposite for high-performance supercapacitors

A novel cobalt sulfide/vertical graphene (CoS/VG) composite electrode was fabricated via a facile electrodeposition method for high-performance supercapacitor application.