Three-Dimensional Vanadium and Nitrogen Dual-Doped Ti3C2 Film with Ultra-High Specific Capacitance and High Volumetric Energy Density for Zinc-Ion Hybrid Capacitors.

Zinc-ion hybrid capacitors (ZICs) can achieve high energy and power density, ultralong cycle life, and a wide operating voltage window, and they are widely used in wearable devices, portable electronics devices, and other energy storage fields. The design of advanced ZICs with high specific capacity and energy density remains a challenge. In this work, a novel kind of V, N dual-doped Ti3C2 film with a three-dimensional (3D) porous structure (3D V-, N-Ti3C2) based on Zn-ion pre-intercalation can be fabricated via a simple synthetic process. The stable 3D structure and heteroatom doping provide abundant ion transport channels and numerous surface active sites. The prepared 3D V-, N-Ti3C2 film can deliver unexpectedly high specific capacitance of 855 F g-1 (309 mAh g-1) and demonstrates 95.26% capacitance retention after 5000 charge/discharge cycles. In addition, the energy storage mechanism of 3D V-, N-Ti3C2 electrodes is the chemical adsorption of H+/Zn2+, which is confirmed by ex situ XRD and ex situ XPS. ZIC full cells with a competitive energy density (103 Wh kg-1) consist of a 3D V-, N-Ti3C2 cathode and a zinc foil anode. The impressive results provide a feasible strategy for developing high-performance MXene-based energy storage devices in various energy-related fields.

Thioacetamide-induced Ce2O2S nanostructures with tunable morphology for supercapacitors in wide pH range.

Here, Rare-earth metal oxysulfide Ce2O2S nanostructures with tunable morphology are successfully grown on carbon cloth (CC) for supercapacitors (SCs) via a facile hydrothermal process followed by pyrolysis treatment for the first time. The feeding amount of sulfur source thioacetamide (TAA) plays an important role in the formation of Ce2O2S nanostructures with tunable morphology. Adjusting TAA feeding amount from 0.5 to 1.0, 1.5, and 2.0 g, the morphology of the resulted Ce2O2S nanostructure can change from pine bark-like agglomerated nanoparticles to fan-shaped nanosheets with edged branches, cuttlefish-like nanostructure with long terminal whiskers and polygon prism with spikes. Among them, Ce2O2S/CC-1.0 g TAA nanostructure with largest specific surface area and abundant mesopores exhibits a high specific capacitance of 670, 321.5 or 588.3 mF cm-2 at 1 mA cm-2 in an acid, neutral or alkaline electrolyte, respectively. Moreover, Ce2O2S/CC-1.0 g TAA electrode delivers excellent cycling stability with high capacitance retention of 93% after 5000 cycles in alkaline electrolyte. Our findings present a new strategy to fabricate rare-earth metal oxysulfide Ce2O2S nanostructures with controllable morphology and systematically reveal their electrochemical performance for SCs, moreover, provide new perspectives for boosting the preparation and application of metal oxysulfides in energy storage.