Researchers At Saudi University Claim Storage Breakthrough With Zinc-Ion Batteries

Researchers at Saudi Arabia’s King Abdullah University of Science and Technology (KAUST) claim to have developed a new zinc-ion battery chemistry that they hope will deliver large-scale energy storage that is cheaper, safer, and more environmentally friendly than the commonly used lithium-ion batteries.

The research summary states that rechargeable Zn-ion batteries are highly promising for stationary energy storage because of their low cost and intrinsic safety. However, due to the poor reversibility of Zn anodes and dissolution of oxide cathodes, aqueous Zn-ion batteries encounter rapid performance degradation when operating in conventional low-concentration electrolytes.

They demonstrate that an aqueous Zn²⁺ electrolyte using a supporting Na salt at a high concentration is efficient to address these issues without sacrificing the power densities, cycling stability, and safety of zinc-ion batteries. A high-concentration solute minimizes the number of free water molecules and the changes in the electronic state of the electrolyte.

A combination of experimental and theoretical investigations reveals that a unique interphase, formed on the Zn anode, enables reversible and uniform Zn plating. Utilizing a cathode of sodium vanadate synthesized through a scalable strategy, the Zn–sodium vanadate battery with the concentrated bi-cation electrolyte shows improved cycling stability, decent rate performance, and low self-discharge.

The research focused on the biggest issue with zinc-ion batteries. Rapid degradation. To combat this, the research team from KAUST developed a water electrolyte with a very high salt concentration. The higher salt concentration, or salt ions in the electrolyte solution served to bind the surrounding water molecules, leading to fewer free water molecules available to damage the battery electrodes. Water electrolytes were a major reason for rapid degradation during use earlier.

By adding sodium to produce a highly concentrated electrolyte of zinc perchlorate and sodium perchlorate. water solubility was further reduced.

This combination has managed to allow for the expression of the best features of zinc ion batteries, namely  high ionic conductivity, safety or environmental friendliness, says lead researcher Yunpei Zhu, a lead scientist in the team.

To compliment the water based low soluble electrolyte, the KAUST team also developed a new nanofiber-based cathode material for batteries.

“The nanofiber morphology enhances ion diffusion, which ensures faster charge and discharge rates of the aqueous Zn-ion batteries,” said Husam Alshareef, Professor of Material Science and Engineering at KAUST and leader of the research group.

“This combination of electrode and electrolyte potentially solves the shortcomings of conventional aqueous Zn-ion batteries.”

The team claims that the results have been promising, with no significant capacity decay over as many as 2,000 charge cycles.

The findings have been published in the research journal Energy & Environmental Science – entitled “Concentrated dual-cation electrolyte strategy for aqueous zinc-ion batteries” .

Progress with alternates to Lithium ion batteries, especially using metals like Iron, Aluminium or Zinc is tracked closely due to the sheer ease it could bring for manufacturers. All these metals could potentially bring down manufacturing and storage costs massively, considering their ease of availability, vis a vis the many components in a Lithium Ion battery that are a challenge to source, from cobalt, to nickel and more. One reason why even Lithium batteries have a Lithium Iron Phosphate (LFP) version which is being actively manufactured now, especially in China.

For emerging large markets like India, a battery utilising Zinc or Iron or Aluminium as the primary metal would be welcome, as all three metals are available abundantly in the country.