Anodic behavior of Mg in acidic AlCl3–1-ethyl-3-methyl-imidazolium chloride ionic liquid

Three-Dimensional Nitrogen-Doped Carbonaceous Networks Anchored with Cobalt as Separator Modification Layers for Low-Polarization and Long-Lifespan Aluminum-Sulfur Batteries

Aluminum-sulfur (Al-S) batteries have attracted extensive interest due to their high theoretical energy density, inherent safety, and low cost. However, severe polarization and poor cycling performance significantly limit the development of Al-S batteries. Herein, three-dimensional (3D) nitrogen-doped carbonaceous networks anchored with cobalt (Co@CMel-ZIF) is proposed as a separator modification layer to mitigate these issues, prepared via carbonizations of a mixture of ZIF-7, melamine, and CoCl2. It exhibits a 3D network structure with a moderate surface area and high average pore diameter, which is demonstrated to be effective in adsorbing the aluminum polysulfides and hindering the mobility of polysulfides across the separator for enhanced cyclic stability of Al-S batteries. Meanwhile, Co@CMel-ZIF are characterized by abundant catalytic pyridinic-N and Co-Nx active sites that effectively eliminate the barrier of sulfides' conversion and thereby facilitate the polarization reduction. As a result, Al-S cells based on the separator modified with Co@CMel-ZIF exhibit a low voltage polarization of 0.47 V under the current density of 50 mA g-1 at 20 °C and a high discharge specific capacity of 503 mAh g-1 after 150 cycles. In contrast, the cell employing a bare separator exhibits a polarization of 1.01 V and a discharge capacity of 300 mAh g-1 after 70 cycles under the same conditions. This work demonstrates that modifying the separators is a promising strategy to mitigate the high polarization and poor cyclability of Al-S batteries.

Design and Fabrication of a Sandwichlike Zn/Cu/Al-Zr Coating for Superior Anticorrosive Protection Performance of ZM5 Mg Alloy

A new three-layered film was fabricated on magnesium (Mg) alloy via electroplating to guard against corrosion in a chloride aqueous environment, which consisted of an underlying double-layered zinc/copper (Zn/Cu) and a top aluminum-zirconium (Al-Zr) layer. The Zn/Cu underlayers not only impeded the galvanic corrosion between the Al-Zr coating and Mg alloy but also improved the adhesive ability between the substrate and the upper Al-Zr layer. Herein, we discussed the nucleus sizes of Al-Zr coatings at the stage of nucleation carried out with different contents of ZrCl₄ in AlCl₃-1-butyl-3-methylimidazolium chloride ionic liquid. The sandwichlike three-layered Zn/Cu/Al-Zr coatings were systematically investigated by surface morphology, phase structure, hardness, anticorrosion performances, and first-principles calculations. The corrosion current density declined from 1.461 × 10^-3 A·cm^-2 of bare Mg to 4.140 × 10^-7 A·cm^-2 of the Zn/Cu/Al-Zr3 sample. Neutral salt spray testing demonstrated that the Zn/Cu/Al-Zr3 sample showed no evident signs of corrosion after 6 days of exposure. The enhancement of the corrosion protection property was related to the fact that the application of the Cu layer changed the corrosion direction from initial longitudinal corrosion to extended lateral corrosion and the top Al-Zr coating hindered the transmission of aggressive ions. In addition, upon increasing the Zr content in the alloy films, the Fermi energy reduced initially and then increased. The Al-Zr3 alloy with 8.3 atom % Zr showed the lowest Fermi energy (-3.0823 eV), which exhibited the most efficient corrosion protection. These results showed that the prepared three-layered coating provided reliable corrosion protection to Mg alloy and may thus promote its practical applications.

Overcoming Electrochemical Instabilities of Printed Silver Electrodes in All-Printed Ion Gel Gated Carbon Nanotube Thin-Film Transistors

Silver ink is the most widely used conductive material for printing electrodes in the fabrication of all-printed ion gel gated transistors because of their high conductivity and low cost. However, electrochemical instability of printed silver electrodes is generally one of the biggest issues, whether it is in air where silver gets oxidized or in a moisture environment where electrochemical migration occurs. Notwithstanding, the electrochemical stability of printed silver electrodes in ion gel medium has not been studied so far. In this work, we studied the electrochemical instabilities of printed silver electrodes in fully printed ion gel gated single-walled carbon nanotube (SWCNT) thin-film transistors (TFTs) and developed some strategies to overcome these issues. All-printed ion gel-based p-type SWCNT TFTs were employed to investigate the impact of electrochemical instabilities on the electrical behavior of printed SWCNT TFTs. The results have demonstrated that printed silver was unstable at anodic and cathodic polarization because of the corrosion by the ionic liquid. Besides, anodic corrosion of silver source/drain electrodes was shown to be responsible for the electrical failure of printed SWCNT TFTs in both the linear and saturated regime. These issues were completely resolved when preventing printed silver electrodes from coming into direct contact with ion gels. For example, ion gels were partially printed in device channels to avoid contacting the printed silver source and drain electrodes. At the same time, silver side-gate electrodes were replaced by inkjet-printed PEDOT:PSS electrodes to avoid gate electrode-related instabilities. Consequently, all-printed electrochemically stable SWCNT TFTs fabricated were obtained with enhanced performance of higher I_ON/I_OFF ratios (10⁵ to 10⁶), smaller subthreshold slopes (∼70 mV/dec), and smaller hysteresis (ΔV = 0.025 V) at gate voltages from 1.2 to -0.5 V. Additionally, the polarity of all-printed SWCNT TFTs was converted from the p-channel to ambipolar while achieving lower leakage currents.