Yinxiang Zeng

Oxygen‐Deficient Hematite Nanorods as High‐Performance and Novel Negative Electrodes for Flexible Asymmetric Supercapacitors

Oxygen-deficient α-Fe2 O3 nanorods with outstanding capacitive performance are developed and demonstrated as novel negative electrodes for flexible asymmetric supercapacitors. The asymmetric-supercapacitor device based on the oxygen-deficient α-Fe2 O3 nanorod negative electrode and a MnO2 positive electrode achieves a maximum energy density of 0.41 mW·h/cm(3) ; it is also capable of charging a mobile phone and powering a light-emitting diode indicator.

A Novel Exfoliation Strategy to Significantly Boost the Energy Storage Capability of Commercial Carbon Cloth

A facile and efficient electrochemical oxidation method to directly activated carbon cloth as an excellent electrode material for supercapacitors is reported. Flexible asymmetric supercapacitor devices based on activated carbon cloth anodes reach a remarkable energy density and excellent long-term durability.

Water Surface Assisted Synthesis of Large‐Scale Carbon Nanotube Film for High‐Performance and Stretchable Supercapacitors

A kind of multiwalled carbon-nanotube (MWCNT)/polydimethylsiloxane (PDMS) film with excellent conductivity and mechanical properties is developed using a facile and large-scale water surface assisted synthesis method. The film can act as a conductive support for electrochemically active PANI nano fibers. A device based on these PANI/MWCNT/PDMS electrodes shows good and stable capacitive behavior, even under static and dynamic stretching conditions.

Dual-Doped Molybdenum Trioxide Nanowires: A Bifunctional Anode for Fiber-Shaped Asymmetric Supercapacitors and Microbial Fuel Cells

A novel in situ N and low-valence-state Mo dual doping strategy was employed to significantly improve the conductivity, active-site accessibility, and electrochemical stability of MoO3 , drastically boosting its electrochemical properties. Consequently, our optimized N-MoO3-x nanowires exhibited exceptional performances as a bifunctional anode material for both fiber-shaped asymmetric supercapacitors (ASCs) and microbial fuel cells (MFCs). The flexible fiber-shaped ASC and MFC device based on the N-MoO3-x anode could deliver an unprecedentedly high energy density of 2.29 mWh cm(-3) and a remarkable power density of 0.76 μW cm(-1) , respectively. Such a bifunctional fiber-shaped N-MoO3-x electrode opens the way to integrate the electricity generation and storage for self-powered sources.

Directional Construction of Vertical Nitrogen‐Doped 1T‐2H MoSe2/Graphene Shell/Core Nanoflake Arrays for Efficient Hydrogen Evolution Reaction

The low utilization of active sites and sluggish reaction kinetics of MoSe2 severely impede its commercial application as electrocatalyst for hydrogen evolution reaction (HER). To address these two issues, the first example of introducing 1T MoSe2 and N dopant into vertical 2H MoSe2 /graphene shell/core nanoflake arrays that remarkably boost their HER activity is herein described. By means of the improved conductivity, rich catalytic active sites and highly accessible surface area as a result of the introduction of 1T MoSe2 and N doping as well as the unique structural features, the N-doped 1T-2H MoSe2 /graphene (N-MoSe2 /VG) shell/core nanoflake arrays show substantially enhanced HER activity. Remarkably, the N-MoSe2 /VG nanoflakes exhibit a relatively low onset potential of 45 mV and overpotential of 98 mV (vs RHE) at 10 mA cm-2 with excellent long-term stability (no decay after 20 000 cycles), outperforming most of the recently reported Mo-based electrocatalysts. The success of improving the electrochemical performance via the introduction of 1T phase and N dopant offers new opportunities in the development of high-performance MoSe2 -based electrodes for other energy-related applications.

Holey Tungsten Oxynitride Nanowires: Novel Anodes Efficiently Integrate Microbial Chemical Energy Conversion and Electrochemical Energy Storage

Holey tungsten oxynitride nanowires with superior conductivity, good biocompatibility, and good stability achieve excellent performance as anodes for both asymmetric supercapacitors and microbial fuel cells. Moreover, an innovative system is devised based on these as-prepared tungsten oxynitride anodes, which can simultaneously realize both energy conversion from chemical to electric energy and its storage.

Boosting the Energy Density of Carbon-Based Aqueous Supercapacitors by Optimizing the Surface Charge

The voltage of carbon-based aqueous supercapacitors is limited by the water splitting reaction occurring in one electrode, generally resulting in the promising but unused potential range of the other electrode. Exploiting this unused potential range provides the possibility for further boosting their energy density. An efficient surface charge control strategy was developed to remarkably enhance the energy density of multiscale porous carbon (MSPC) based aqueous symmetric supercapacitors (SSCs) by controllably tuning the operating potential range of MSPC electrodes. The operating voltage of the SSCs with neutral electrolyte was significantly expanded from 1.4 V to 1.8 V after simple adjustment, enabling the energy density of the optimized SSCs reached twice as much as the original. Such a facile strategy was also demonstrated for the aqueous SSCs with acidic and alkaline electrolytes, and is believed to bring insight in the design of aqueous supercapacitors.

Achieving Ultrahigh Energy Density and Long Durability in a Flexible Rechargeable Quasi‐Solid‐State Zn–MnO2 Battery

Advanced flexible batteries with high energy density and long cycle life are an important research target. Herein, the first paradigm of a high-performance and stable flexible rechargeable quasi-solid-state Zn-MnO2 battery is constructed by engineering MnO2 electrodes and gel electrolyte. Benefiting from a poly(3,4-ethylenedioxythiophene) (PEDOT) buffer layer and a Mn2+ -based neutral electrolyte, the fabricated Zn-MnO2 @PEDOT battery presents a remarkable capacity of 366.6 mA h g-1 and good cycling performance (83.7% after 300 cycles) in aqueous electrolyte. More importantly, when using PVA/ZnCl2 /MnSO4 gel as electrolyte, the as-fabricated quasi-solid-state Zn-MnO2 @PEDOT battery remains highly rechargeable, maintaining more than 77.7% of its initial capacity and nearly 100% Coulombic efficiency after 300 cycles. Moreover, this flexible quasi-solid-state Zn-MnO2 battery achieves an admirable energy density of 504.9 W h kg-1 (33.95 mW h cm-3 ), together with a peak power density of 8.6 kW kg-1 , substantially higher than most recently reported flexible energy-storage devices. With the merits of impressive energy density and durability, this highly flexible rechargeable Zn-MnO2 battery opens new opportunities for powering portable and wearable electronics.

Three-dimensional nickel nitride (Ni3N) nanosheets: free standing and flexible electrodes for lithium ion batteries and supercapacitors

The search for suitable electrode materials for electrochemical storage devices has led to the development of new electrode materials. Metal nitrides are regarded as an attractive and promising class of electrode materials for high-performance energy storage devices because they exhibit excellent electrical conductivity over the corresponding metal oxides and have considerably higher capacity than carbon based materials. Moreover, designing of different electrode nanostructures has been demonstrated to effectively improve the storage performance of energy storage devices. Hence, three dimensional (3D) nickel nitride (Ni3N) nanosheets were successfully fabricated on a carbon cloth by a simple hydrothermal and post annealing process that can be used directly as electrode storage materials for flexible lithium ion batteries and supercapacitors. Due to the electrode, architectures that demonstrated fast electron transport via direct connection to the flexible substrate and facile ion diffusion paths that ensured the participation of every nanosheet in the ultrafast electrochemical reaction, the 3D flexible Ni3N/carbon composites cloth exhibited a high capacity or capacitance and possessed an excellent rate performance.

Flexible Ultrafast Aqueous Rechargeable Ni//Bi Battery Based on Highly Durable Single-Crystalline Bismuth Nanostructured Anode

A new type of ultrafast Ni//Bi battery with high flexibility and impressive electrochemical performance is demonstrated for the first time based on an as-prepared Bi electrode as the anode and a NiCo2 O4 nanowire electrode as the cathode. The NiCo2 O4 //Bi battery is able to deliver a remarkable energy density of 85.8 W h kg-1 at a power density of 1.02 kW kg-1 , and still retains 55.4 W h kg-1 when the power density is increased to 21.2 kW kg-1 .