Researchers from the Chinese Academy of Sciences have constructed an air-breathing cathode in nickel-zinc (Ni-Zn) batteries that provided an ultra-long lifespan and ultra-high energy efficiency.
The research may be key in developing future batteries for electric vehicles or other industrial machines as the world transitions to greener type fuel sources.
This research used a side oxygen evolution reaction (OER) in Ni-Zn batteries by coupling electrocatalysts for oxygen reduction reactions (ORR) in the cathode.
Why it matters
Nickel-zinc batteries have a high output voltage, high safety, low cost and high specific energy but since the cathodic side reaction of oxygen results in low energy efficiency and poor stability.
OER is something that can’t be stopped, and it reduces energy efficiency leading to poor energy storage and releasing capabilities. Although the OER in the cathode can be partially suppressed by controlling the charging voltage and using electrolyte additives, these strategies do not completely solve the OER issue in Ni-Zn batteries.
By coupling electrocatalysts for ORR in the cathode, the approach allows the oxygen generating during charging via the OER to be utilized during discharge, like an air-breathing mechanism.
In these so-called Ni-ZnAB batteries, the OER in the cathode was no longer an undesirable side reaction during the charging process and the efficiency loss from nickel hydroxide could be compensated by the ORR. Compared to conventional Ni-Zn batteries, this improved cycling stability and energy efficiency.
The pouch-type Ni-ZnAB battery showed:
- A cycling performance of 100 hours
- A capacity of 45 mAh
- An average energy efficiency of 85.1%
According to the Chinese Academy of Sciences, this shows the potential of the new battery for practical applications.
"Our results highlight the importance of incorporating air-breathing cathode in Ni-Zn cells to improve their stability and energy efficiency and showcase the potential of Ni-ZnAB batteries as a valuable guide for designing highly stable Ni-Zn batteries," said Yang Weishen, professor at the Dalian Institute of Chemical Physics at the Chinese Academy of Sciences.
The full research can be found in the Wiley Online Library.
