Jingling Ma

A method was proposed to synthesize hollow flower-like NiCo ₂ O ₄ composed of porous nanosheets using a self-template approach. The unique structure is attributed to the synergistic effect of the Kirkendall effect and the Ostwald ripening mechanism. The sheet-like and porous structure endowed the material with a specific surface area of 137.1 m ² g ⁻¹ and a pore volume of 0.418 cm ³ g ⁻¹ . The distinctive structure and high-density active sites imparted excellent catalytic performance in oxygen reduction (ORR) and oxygen evolution (OER) reactions. Electrochemical tests showed that the limit current density of ORR reached 5.58 mA cm ⁻² , comparable to that of the noble metal Pt/C (20 wt%). The overpotential of OER at a current density of 10 mA cm ⁻² was only 380 mV, significantly lower than that of the noble metal RuO ₂ . These results indicate that the synthesized hollow flower-like NiCo ₂ O ₄ has the potential to replace noble metals in ORR and OER catalytic applications.

An alkaline gel polymer electrolyte, namely a poly (acrylic acid)-zinc acetate (Zn(AC) ₂ )-aquatic colloidal graphene (ACG) solution (PAA-Zn(AC) ₂ -ACG), was prepared by solution casting method. Properties of PAA-Zn(AC) ₂ -ACG were studied by Fourier transform infrared spectrometer (FTIR), scanning electron microscopy (SEM), AC impedance, cyclic voltammetry (CV) and water retention ability. Results obtained show that PAA-Zn(AC) ₂ -ACG exhibits a high ionic conductivity of 407.9 mS·cm ^–1 , an electrochemical stability window of 1.7 V, and 72.5% water retention ability. Flexible zinc-air batteries (ZABs) with PAA-Zn(AC) ₂ -ACG gel polymer electrolyte have an better discharge capacity of 672 mAh g ⁻¹ Zn at 0.5 mA·cm ^–2 (current density), a continuous charge-discharge duration of 43.3 h, 130 cycles, and a cycle efficiency of 64.8%. Based on work done in this study, it can be concluded that flexible ZABs have advantageous prospects and large potential for practical applications.

This paper reports on the improvement of discharge performances of magnesium-air batteries by adding sodium phosphate and sodium dodecylbenzenesulfonate to sodium chloride aqueous solution. Four different electrolytes are tested. Results obtained show that the discharge potential and anode utilization of magnesium-air battery increase significantly with addition of the additives. With an electrolyte of 3.5 wt% sodium chloride+0.5 g·L⁻¹ sodium phosphate, the discharge potential increases from 1.120 V to 1.150 V and the anode utilization increases from 44.1% to 49.1%. The self-corrosion rate of anode has a tendency to decrease with addition of the additives. In solution of 3.5 wt% sodium chloride+0.5 g·L⁻¹ sodium dodecylbenzenesulfonate +0.5g·L⁻¹ sodium phosphate, the self-corrosion is low and the inhibition efficiency can reach 95.2%.