Bingwei Chen

An Aqueous Rechargeable Zn//Co3O4 Battery with High Energy Density and Good Cycling Behavior

An aqueous rechargeable Zn//Co3 O4 battery is demonstrated with Zn@carbon fibers and Co3 O4 @Ni foam as the negative and positive electrodes, respectively, using an electrolyte of 1 m KOH and 10 × 10(-3) m Zn(Ac)2 . It can operate at a cell voltage as high as 1.78 V with an energy density of 241 W h kg(-1) and presents excellent cycling. The battery is also assembled into a flexible shape, which can be applied in flexible or wearable devices requiring high energy.

A Zn–NiO rechargeable battery with long lifespan and high energy density

A Zn–NiO rechargeable battery comprising a NiO nanosheet anchored to CNTs as the positive electrode, a zinc plate as the negative one and an alkaline solution of 1 M KOH and 10 mM Zn(Ac)2 as the electrolyte is reported. It delivers a voltage of ∼1.75 V and a high energy density of 228 W h kg−1 (based on the mass of the positive electrode composite and zinc) with good cycling. It has great promise for practical energy storage applications.

Core–shell MnO2@Fe2O3 nanospindles as a positive electrode for aqueous supercapacitors

Supercapacitors display high power density and long cycling life that are particularly amenable for use in the field of energy storage. However, the cost is a big issue for practical application. Here, cheap Fe2O3 spindles from a rich natural resource are used as the positive electrode. Through the twining of MnO2 nanoflakes via a simple and cost-effective hydrothermal method, a unique structure of a core–shell MnO2@Fe2O3 nanospindle has been prepared. The electrochemical performance of the nanospindles including capacitance and cycling life is markedly improved compared with the pristine Fe2O3 spindles. Its specific capacitance is up to 159 F g−1 at a current density of 0.1 A g−1 and especially, the capacitance retention is 97.4% after 5000 cycles in a 0.5 mol L−1 K2SO4 neutral aqueous electrolyte. Combined with activated carbon as the negative electrode, the energy density can be up to 43.8 W h kg−1 on the basis of the weights of the two electrodes. These results reveal that the core–shell MnO2@Fe2O3 nanospindles are a promising positive electrode for practical supercapacitors.

A gel polymer electrolyte based on composite of nonwoven fabric and methyl cellulose with good performance for lithium ion batteries

A new composite gel polymer electrolyte of nonwoven fabric (NWF) and methyl cellulose (MC) with good mechanical properties and outstanding thermal and electrochemical stability is prepared by a simple and green casting process followed by absorbing liquid electrolyte. Its characteristics are investigated by scanning electron microscopy, FT-IR, thermogravimetric analysis (TGA). Due to the synergistic action between MC matrix and the NWF framework, the composite gel polymer electrolyte achieves higher ionic conductivity (0.29 mS cm−1) at ambient temperature and larger lithium ion transference number (0.34) than those for the conventional Celgard 2730 separator (0.21 mS cm−1 and 0.27, respectively) in 1 mol L−1 LiPF6 electrolyte, and their activation energies are similar. In addition, the composite membrane shows better mechanical strength than the pure MC membrane. The evaporation rate of the liquid electrolyte at elevated temperature is much decreased. The assembled Li//LiFePO4 cell using this composite gel membrane exhibits better cycling retention and higher discharge capacity than those based on Celgard 2730 separator and pure MC gel membrane. These fascinating characteristics suggest that this unique composite gel polymer electrolyte can be used for lithium ion batteries with good performance and low cost.

Enhanced capacitive desalination of MnO2 by forming composite with multi-walled carbon nanotubes

The morphology and structure of the prepared MnO2/MWCNTs (multi-walled carbon nanotubes) composite are characterized by XRD, SEM, TEM, and N2 sorption analysis. The electrochemical performance of the composite is studied by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge/discharge evaluation. The composite has a specific capacitance of 144 F g−1 at the current density of 1 A g−1. It has higher conductivity which is affirmed by electrochemical impedance spectroscopy (EIS). The capacitive deionization (CDI) test was conducted in a bath mode apparatus by assembling a capacitor. The capacitor made from MnO2/MWCNTs composite shows a higher desalination capacity of (6.65 mg g−1) in NaCl aqueous solution, higher than that made from the virginal MnO2 (1.60 mg g−1) and those of the formerly reported. Furthermore, the MnO2/MWCNTs composite electrode shows excellent recyclability with an efficient and rapid regeneration process.

Enhancing performance of sandwich-like cobalt sulfide and carbon for quasi-solid-state hybrid electrochemical capacitors

Metal sulfides (MSs) should be feasible candidates for hybrid electrochemical capacitors (HECs) due to their high theoretical specific capacitances. However, their performances are largely hampered by sluggish ion/electron transport kinetics and fast capacitance fading. Here, we provide a new approach to fabricate high-performance dual-structural MSs for long-life electrochemical energy storage devices. With robust, graphitic and nitrogen-doped porous carbon shells and highly conductive reduced graphene oxide (RGO) substrates, our cobalt sulfide-based composite shows 99.7% capacitance retention after 4000 cycles. We also present a sandwich-like carbon electrode with ultrahigh specific capacitance and excellent cycling stability. As a result, a quasi-solid-state HEC comprising the above-mentioned electrodes and a PVA–PAA membrane is fabricated. Its electrochemical performance is superior to those formerly reported for MSs, and our results for the first time provide a solid base for the application of MSs in HECs.

A lithium ion battery using an aqueous electrolyte solution

Energy and environmental pollution have become the two major problems in today’s society. The development of green energy storage devices with good safety, high reliability, high energy density and low cost are urgently demanded. Here we report on a lithium ion battery using an aqueous electrolyte solution. It is built up by using graphite coated with gel polymer membrane and LISICON as the negative electrode, and LiFePO4 in aqueous solution as the positive electrode. Its average discharge voltage is up to 3.1 V and energy density based on the two electrode materials is 258 Wh kg−1. It will be a promising energy storage system with good safety and efficient cooling effects.

A Cr2O3/MWCNTs composite as a superior electrode material for supercapacitor

It has been a challenge to achieve a good capacitive performance for Cr-based oxides, and only few studies have been reported on these oxides. Herein, a composite of chromium oxide (Cr2O3) and multi-walled carbon nanotubes (MWCNTs) was prepared by a simple hydrothermal procedure followed by thermal decomposition. The Cr2O3 nanoparticles were evenly decorated on the surface of MWCNTs. The prepared Cr2O3/MWCNTs composite exhibited superior electrochemical performance in a 1 M KOH electrolyte, i.e., 257 F g−1 at the current density of 0.25 A g−1, and the capacity fade was only 12% after 3000 cycles. In addition, the Cr2O3/MWCNTs//AC asymmetric capacitor has high energy density (15.2 W h kg−1 at 266 W kg−1). The abovementioned results for the first time indicate the potential application of Cr2O3 as an electrode material for supercapacitors.

CoCO 3 from one-step micro-emulsion method as electrode materials for Faradaic capacitors

Faradaic capacitor (FC) has been widely investigated during the past few decades, and dozens of prototypes have been proposed. However, it has not reached its full potential. In this work, we demonstrate a kind of FC comprising of a CoCO3 electrode. Synthesized through a micro-emulsion route, such CoCO3 shows low crystallinity and porous wool-ball structures stacked by needle-like individuals. It shows desirable electrochemical properties in terms of excellent high-rate performance and high reversibility. Also, it could deliver a capacitance of 440 F·g−1 at 1 A·g−1, and shows no capacitance decay after 1000 cycles. Since metal carbonate is capable of delivering good electrochemical performances and its preparation is easier and more cost-efficient, it should be a feasible candidate for electrode material of FC.