Abstract
Zn-air batteries have promise as the next generation of batteries. However, their self-discharge behavior due to the hydrogen evolution reaction (HER) and corrosion of the Zn anode reduce their electrochemical performance. Copper (II) oxide (CuO) effectively suppresses the corrosion and HER. In addition, different electrochemical behavior can be obtained with different shape of nano CuO. To improve the performance of Zn-air batteries, in this study we synthesized nano CuO by the hydrothermal synthesis method with different volumes of NaOH solutions. Materials were characterized by XRD, FE-SEM, and EDX analysis. The sphere-like nano CuO (S-CuO) showed a specific discharge capacity of 428.8 mAh/g and 359.42 mAh/g after 1 h and 12 h storage, respectively. It also showed a capacity retention rate of 83.8%. In contrast, the other nano CuO additives showed a lower performance than pure Zn. The corrosion behavior of nano CuO additives was analyzed through Tafel extrapolation. S-CuO showed an Icorr of 0.053 A/cm2, the lowest value among the compared nano CuO materials. The results of our comparative study suggest that the sphere-like nano CuO additive is the most effective for suppressing the self-discharge of Zn-air batteries.
Highlights
As the battery market has developed, both existing lithium-ion batteries and their alternatives have attracted attention
To compare the self-discharge behavior of the different types of nano CuO in a Znair cell, 1.0 wt% of sphere-like nano CuO (S-CuO), L-CuO, and C-CuO were added to the electrolytes
For the two strongest peaks, those of L-CuO are sharper than those observed in S-CuO, which is seen as an increase in the volumes of NaOH
Summary
As the battery market has developed, both existing lithium-ion batteries and their alternatives have attracted attention. Lithium-ion batteries (LIBs) are used in various fields, such as electric vehicles (EV) [1], energy storage systems (ESSs) [2] and mobile devices due to their high specific energy density and charging efficiency [3,4,5,6,7,8,9]. Li-air batteries have the potential to deliver the highest energy density and a large cell voltage. They have a safety issue due to an unstable anode in the presence of atmospheric moisture [15]. The corrosion factors were measured using the Tafel extrapolation method
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