Performance improvement of aqueous zinc batteries by zinc oxide and Ketjen black co-modified glass fiber separators.

Rechargeable aqueous zinc-based batteries (AZBs) are intriguing candidates for next-generation energy storage batteries. However, the dendrites generated plagued their development during charging. To inhibit the dendrite generation, a novel modification method based on the separators was proposed in this study. The separators were co-modified by spraying sonicated Ketjen black (KB) and zinc oxide nanoparticles (ZnO) uniformly. The highly conductive KB homogenizes the anode interface's electric field. The deposited ions are deposited on ZnO preferentially rather than on the anode electrode, and the deposited particles can be refined. The ZnO in the uniform KB conductive network can provide sites for zinc deposition, and the by-products of the zinc anode electrode reduced. The Zn-symmetric cell with the modified separator (Zn//ZnO-KB//Zn) can cycle for 2218 h at 1 mA cm-2 stably (the unmodified Zn-symmetric cell (Zn//Zn) only can cycle for 206 h). With the modified separator, the impedance and polarization of Zn//MnO2 reduced, and the cell can charge/discharge 995 times at 0.3 A g-1. In conclusion, the electrochemical performance of AZBs can be improved effectively after separator modification by the synergistic effect of ZnO and KB.

From spent Zn-MnO2 primary batteries to rechargeable Zn-MnO2 batteries: A novel directly recycling route with high battery performance.

For the first time, spent Zn-MnO2 primary batteries are recycled to directly build rechargeable Zn-MnO2 batteries with a mixed solution of sulfuric acid and hydrogen peroxide as the leachate, which aimed to the efficient recovery of spent Zn-MnO2 primary batteries and the realization of high-powered rechargeable Zn-MnO2 batteries. After simple purification, the leached liquid is directly used as the working solution to prepare an electrolytic rechargeable Zn-MnO2 battery. The experimental results show that the performance of the recycling solution of the neutral Zn-MnO2 primary battery was better than that of the alkaline Zn-MnO2 primary battery, and both performed better than the solution prepared with chemically pure reagents. After optimizing the pH of the working solution and charging current, the obtained rechargeable Zn-MnO2 battery can provide an energy efficiency of 72.33 % ± 0.55, a coulombic efficiency of 90.17 % ± 0.71, and excellent cycle stability. These experimental results show that spent Zn-MnO2 primary batteries can be successfully recycled to prepare rechargeable Zn-MnO2 batteries, demonstrating very good application potential.

A Novel Cr2O3/MnO2-x Electrode for Lithium-Oxygen Batteries with Low Charge Voltage and High Energy Efficiency.

A high energy efficiency, low charging voltage cathode is of great significance for the development of non-aqueous lithium-oxygen batteries. Non-stoichiometric manganese dioxide (MnO2-x) and chromium trioxide (Cr2O3) are known to have good catalytic activities for the discharging and charging processes, respectively. In this work, we prepared a cathode based on Cr2O3 decorated MnO2-x nanosheets via a simple anodic electrodeposition-electrostatic adsorption-calcination process. This combined fabrication process allowed the simultaneous introduction of abundant oxygen vacancies and trivalent manganese into the MnO2-x nanosheets, with a uniform load of a small amount of Cr2O3 on the surface of the MnO2-x nanosheets. Therefore, the Cr2O3/MnO2-x electrode exhibited a high catalytic effect for both discharging and charging, while providing high energy efficiency and low charge voltage. Experimental results show that the as-prepared Cr2O3/MnO2-x cathode could provide a specific capacity of 6,779 mA·h·g-1 with a terminal charge voltage of 3.84 V, and energy efficiency of 78%, at a current density of 200 mA·g-1. The Cr2O3/MnO2-x electrode also showed good rate capability and cycle stability. All the results suggest that the as-prepared Cr2O3/MnO2-x nanosheet electrode has great prospects in non-aqueous lithium-oxygen batteries.

Improving the Conductivity of Solid Polymer Electrolyte by Grain Reforming.

Polyethylene oxide (PEO)-based solid polymer electrolyte (SPE) is considered to have great application prospects in all-solid-state li-ion batteries. However, the application of PEO-based SPEs is hindered by the relatively low ionic conductivity, which strongly depends on its crystallinity and density of grain boundaries. In this work, a simple and effective press-rolling method is applied to reduce the crystallinity of PEO-based SPEs for the first time. With the rolled PEO-based SPE, the LiFePO4/SPE/Li all-solid li-ion battery delivers a superior rechargeable specific capacity of 162.6 mAh g-1 with a discharge-charge voltage gap of 60 mV at a current density of 0.2 C with a much lower capacity decay rate. The improvement of electrochemical properties can be attributed to the press-rolling method, leading to a doubling conductivity and reduced activation energy compared with that of electrolyte prepared by traditional cast method. The present work provides an effective and easy-to-use grain reforming method for SPE, worthy of future application.

Facile preparation of a Ag/graphene electrocatalyst with high activity for the oxygen reduction reaction.

Small Ag nanoparticles are well dispersed onto graphene sheets via a simple and environmentally friendly route using disposable paper-cups. The obtained Ag/graphene materials exhibit much higher catalytic activity for the oxygen reduction reaction than the conventional Ag/graphene catalyst does in alkaline media.