Enabling superior hybrid capacitive deionization performance in NASICON-structured Na3MnTi(PO4)3/C by incorporating a two-species redox reaction

Scalable polyolefin-based all-organic dielectrics with superior high-temperature capacitive energy storage performance

Superior capacitive performances of binary nickel–cobalt hydroxide nanonetwork prepared by cathodic deposition

Porous MnO2 hollow spheres constructed by nanosheets and their application in electrochemical capacitors

Fabrication of 3D flower-like MoS2/graphene composite as high-performance electrode for capacitive deionization

Finding earth-abundant and high-performance electrode materials for supercapacitors is a demanding challenge in the energy storage field. Cuprous oxide (Cu2O) has attracted increasing attention due to its theoretically high specific capacitance, however, the development of Cu2O-based electrodes with superior capacitive performance is still challenging. We herein report a simple and effective ionic-liquid-assisted sputtering approach to synthesizing the Cu2O nanoparticles/multi-walled carbon nanotubes (Cu2O/MWCNTs) nanocomposite for high-performance asymmetric supercapacitors. The Cu2O/MWCNTs nanocomposite delivers a high specific capacitance of 357 F g−1, good rate capability and excellent capacitance retention of about 89% after 20 000 cycles at a current density of 10 A g−1. The high performance is attributed to the uniform dispersion of small-sized Cu2O nanoparticles on conductive MWCNTs, which offers plenty of redox active sites and thus improve the electron transfer efficiency. Oxygen vacancies are further introduced into Cu2O by the NaBH4 treatment, providing the oxygen-deficient Cu2O/MWCNTs (r-Cu2O/MWCNTs) nanocomposite with significantly improved specific capacitance (790 F g−1) and cycling stability (∼93% after 20 000 cycles). The assembled asymmetric supercapacitor based on the r-Cu2O/MWCNTs//activated carbon (AC) structure achieves a high energy density of 64.2 W h kg−1 at 825.3 W kg−1, and long cycling life. This work may form a foundation for the development of both high capacity and high energy density supercapacitors by showcasing the great potential of earth-abundant Cu-based electrode materials.

The ion storage mechanism and ion concentration play crucial roles in determining the electrochemical energy storage performances of multi-ion-based batteries and/or capacitors. Here, we take δ-MnO2-A2SO4 (A = Li, Na, K) as an example system to explore the physical and chemical mechanisms related to electrochemical energy storage using experimental analysis and first-principles calculations. Among the studied systems, superior capacitance performance is found in δ-MnO2-Li2SO4 due to excellent mobility (migration barrier 0.168 eV) of lithium ions. Better cycling stability appears in δ-MnO2-K2SO4, which is attributed to larger adsorption energy (−0.655 eV) between potassium ions and δ-MnO2. Moreover, compared with a pure Li2SO4 electrolyte, our calculations suggest that incorporation of moderate Na2SO4 or K2SO4 into the Li2SO4 electrolyte could considerably elongate the cycling lifetime. Overdose of Na+ or K+ is, however, adverse to the capacitance performance as verified by our experiments. We argue that the dominance role of Na+ or K+ ions played in the hybrid electrolyte originates from the larger formation enthalpy and adsorption energy of Na+ or K+ when reacting with δ-MnO2 compared with those of Li+. Our findings suggest that understanding of the ion storage mechanism can provide useful clues for searching the proper ion concentration ratio, which takes advantages of individual ions in multi-ion-based δ-MnO2 electrochemical energy storage devices.

3D porous PEDOT/MXene scaffold toward high-performance supercapacitors

Facile fabrication of multiwalled carbon nanotube/α-MnOOH coaxial nanocable films by electrophoretic deposition for supercapacitors

High-temperature high-performance capacitive energy storage in polymer nanocomposites enabled by nanostructured MgO fillers

Bi-Fe chalcogenides anchored carbon matrix and structured core–shell Bi-Fe-P@Ni-P nanoarchitectures with appealing performances for supercapacitors

Effects of annealing holding time on capacitance performance of RuO2–IrO2–graphene/Ti electrodes

Petal-shaped poly(3,4-ethylenedioxythiophene)/sodium dodecyl sulfate-graphene oxide intercalation composites for high-performance electrochemical energy storage

Graphene and N-doped graphene were synthesized by a solvothermal process, and their composites with SnO2 nanoparticles were prepared by a facile one-pot chemical solution method. The corresponding films were fabricated by a blade coating process and followed by heat treatment at 400 degrees C for 1 h. All-solid-state supercapacitors were fabricated with graphene based films and a polymer gel of polyvinyl alcohol/H3PO4 as electrodes and electrolyte, respectively. The capacitance performance of the as-fabricated supercapacitors was characterized. The results suggest that compared with graphene, N-doped graphene exhibits larger crystalline size, lower specific surface area, yet superior capacitance performance, and the incorporation of SnO2 nanoparticles on graphene and N-doped graphene sheets enhances their capacitive characteristics.

A series of hierarchical activated mesoporous carbons (AMCs) were prepared by the activation of highly ordered, body-centered cubic mesoporous phenolic-resin-based carbon with KOH. The effect of the KOH/carbon-weight ratio on the textural properties and capacitive performance of the AMCs was investigated in detail. An AMC prepared with a KOH/carbon-weight ratio of 6:1 possessed the largest specific surface area (1118 m(2) g(-1)), with retention of the ordered mesoporous structure, and exhibited the highest specific capacitance of 260 F g(-1) at a current density of 0.1 A g(-1) in 1 M H2 SO4 aqueous electrolyte. This material also showed excellent rate capability (163 F g(-1) retained at 20 A g(-1)) and good long-term electrochemical stability. This superior capacitive performance could be attributed to a large specific surface area and an optimized micro-mesopore structure, which not only increased the effective specific surface area for charge storage but also provided a favorable pathway for efficient ion transport.

Highly stable multi-wall carbon nanotubes@poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) core–shell composites with three-dimensional porous nano-network for electrochemical capacitors