This invention provides a method to recharge a Zn-air battery while ensuring good coulombic efficiency. It is achieved by carrying out the zinc plating in the presence of a water-in-salt electrolyte (electrolytes having solute concentrations > 25 m) and the oxygen evolution reaction in the presence of low concentration (< 1 M) zinc based aqueous electrolyte. These reactions have been carried out in two isolated chambers, each with one auxiliary electrode along with the Zn electrode and/or the air electrode, ensuring that the two electrolytes are also isolated from each other. The purpose of the auxiliary electrodes is to undergo an electrochemical reaction in such a way that Zinc ions are intercalated in one part and they are de-intercalated in the other part.
Figure (1) (a)Image of the cell and (b) the electrodes used; (2) Charge-discharge curve of V2O5 in 30 m ZnCl2 with 100μA current
Alkaline Zn-air batteries have been known for more than a century in the form of a primary battery. There are, however, multiple challenges in implementing true electrical rechargeability for alkaline Zn-air batteries. One of the major challenges is the significant parasitic hydrogen evolution during plating of the zinc on the negative electrode, which results in low coulombic efficiency of the battery. Further, in alkaline electrolytes, the discharge of the battery results in formation of a passive oxide layer on the surface of the electrode that hinders the zinc dissolution and plating processes. Thus, there is a need to develop an efficient electrical recharging process for the Zn-air battery.
The key technical innovation is the use of a water-in-salt (WIS) electrolyte during the zinc plating step to achieve >90% coulombic efficiency. Additionally, the battery uses separate chambers with electrically connected auxiliary electrodes and isolated electrolytes, enabling efficient and reversible zinc-air battery recharging while minimizing parasitic reactions.
- The design consists of two chambers, each containing a zinc electrode, an air cathode and an auxiliary electrode in contact with a graphite plate separating the chambers
- The auxiliary electrodes are made of a material which is capable of reversibly intercalating Zn ions in both the aqueous and the non-aqueous medium (V2O5 )
- For the discharge process, both part A and part B are filled with aqueous electrolyte (1 M ZnSO4 ) using pumps and current is drawn till zinc on both sides is exhausted
- For the charging process, Chamber A is filled with WIS electrolyte (30 m ZnCl2 ) while chamber B is filled with low concentration aqueous electrolyte (1 M ZnSO4 )
It is available for licensing
4
This enables the development of rechargeable zinc-air batteries with high efficiency and stability, offering a low-cost, safe, and sustainable alternative to conventional batteries. It supports clean energy storage, reduces reliance on lithium-based systems, and can accelerate adoption of eco-friendly energy solutions in remote or under-resourced areas.
- Sustainability
- Storage
- Electrification
- Energy
Geography of IP
Type of IP
202221001555
411590