The long-term challenges in the practical implementation of rechargeable zinc-air batteries (ZAB) (Improved innovation in zinc-air batteries) are the electrochemical irreversibility of the Zn anode and the damage of the alkaline electrolyte air cathodes, which ultimately results in a poor life cycle and low self-voltage.
In order to improve the novelty of ZAB, every effort has been made to use more viable air cathode catalysts, while reducing corrosion of the Zn anode by electrode construction as an electrolyte additive. These strategies can overcome, but not completely overcome, the major problems associated with a highly alkaline electrolyte. A research team led by ZHANG Xinb of the Changchun Institute of Applied Chemistry (CIAC) of the Chinese Academy of Sciences, took a different approach, recently developed a high voltage stable ZAB hybrid using a neutral Zn anode, acid cathode and double hydrophobic-induced, proton-shuttle shielding membrane to separate two electrodes .
Her findings are published in Joule.
Researchers have found that reversible Zn plating / stripping (Improved innovation in zinc-air batteries
can be achieved with neutral electrolytes, while acidic electrolytes are needed to make the air cathode immune to CO2 poisoning problems. Therefore, they designed a hybrid ZAB by separating the functional environments of the acidic air cathode and the neutral Zn anode.
However, an important requirement for the long-term operation of the hybrid ZAB is that both electrodes operate independently of the respective environments, thus completely and permanently preventing the passage of protons from the catholyte. Based on this requirement, the researchers designed a hydrophobic ionically conductive membrane to create this hybrid proton shuttle shielding system.
Specifically, this hybrid cell produces optimized redox chemistry at the Zn anode and air cathode. This allows strong stripping / deposition of the neutral electrolyte and a high voltage oxygen redox reaction with the acidic electrolyte. As a result, the hybrid ZAB has a high operating voltage of 1.5 V and a long service life of 2000 hours.
ZHANG and his team designed two types of hybrid cell prototypes that use a proton shielding strategy, hydrophobic ion conduction. Both hybrid Zn-Mn batteries and hybrid Zn-Br batteries are expected to have high voltage potential and long life, demonstrating the ability to use such hybrid cells in production.
According to ZHANG: “The emergence of hybrid ZAB could also stimulate the growth of many developing regions, such as acidic ORR / OER in proton exchange membrane fuel cells and electrolyzers.”
