Xianming Wu

Green-low-cost rechargeable aqueous zinc-ion batteries using hollow porous spinel ZnMn2O4 as the cathode material

Rechargeable aqueous zinc-ion batteries (ZIBs) have been receiving much attention recently due to their potential large-scale applications for energy storage, although only a few cathode materials have been reported as the intercalation hosts for divalent Zn2+ ions. Here, we report competitive ZIBs based on hollow porous ZnMn2O4 as the cathode and zinc as the anode. ZnMn2O4 is firstly prepared through a solvothermal carbon template dispersed by polyvinyl pyrrolidone, followed by an annealing process. The galvanostatic charge–discharge measurement demonstrates that a reversible discharge capacity of 106.5 mA h g−1 at 100 mA g−1 after 300 cycles can be achieved with no capacity decay after the addition of 0.05 mol L−1 of MnSO4 into the electrolyte. Meanwhile, it exhibits a high capacity of 70.2 mA h g−1 at a large current density of 3200 mA g−1. The excellent cycle and rate performances are attributed to the synergistic effect of the deficient spinel structure of hollow porous ZnMn2O4 with residual carbon distribution and the inhibition of Mn dissolution during the charge/discharge process.

Preparation and properties of Bi2Ti2O7 thin films by chemical solution deposition

Abstract Homogeneous and crack-free Bi 2 Ti 2 O 7 thin films with strong (111) orientation were successfully prepared on n-type Si (100) substrates by chemical solution deposition. Bismuth nitrate and titanium butoxide were used as starting materials. The crystallization temperature is relatively low and about 500°C.The insulating and dielectric properties were found to be dependent on the annealing temperature. The dielectric constant was 115.5 at 100 kHz at room temperature, and the leakage current density was 3.48 × 10 −7 A/cm 2 at an applied voltage of 15 V (375 kV/cm) for 0.4 μm-thick films annealed at 500°C for 30 min.

The influence of crystallization route on the Bi4Ti3O12 thin films by chemical solution deposition technique

The thickness of the monolayer thin film made from chemical solution deposition (CSD) is often less than 0.1 μm, and in order to get thicker film, multiple coating is unavoidable. In our work, we found that different crystallization routes greatly influence the structural and electrical properties of the films. The leakage current density and dielectric constant of the films prepared by intermediate crystallized layer route are smaller than those of the films made from the intermediate amorphous layer route. The coercive field of the former is bigger than that of the latter, while the remanent polarization of the former is smaller than that of the latter.

Cryptomelane-Type KMn8O16 as Potential Cathode Material — for Aqueous Zinc Ion Battery

Aqueous battery has been gained much more interest for large-scale energy storage fields due to its excellent safety, high power density and low cost. Cryptomelane-type KMn8O16 confirmed by X-ray diffraction (XRD) was successfully synthesized by a modified hydrothermal method, followed by annealed at 400°C for 3 h. The morphology and microstructure of as-prepared KMn8O16 investigated by field-emission scanning electron microscopy (FE-SEM) with the energy spectrum analysis (EDS) and transmission electron microscopy (TEM) demonstrate that one-dimensional nano rods with the length of about 500 nm constitute the microspheres with the diameter about 0.5~2 μm. The cyclic voltammetry measurement displays that the abundant intercalation of zinc ions on the cathode takes place during the initial discharge process, indicating that cryptomelane-type KMn8O16 can be used as the potential cathode material for aqueous zinc ion batteries. The electrode shows a good cycling performance with a reversible capacity of up to 77.0 mAh/g even after 100 cycles and a small self-discharge phenomenon.