New battery tech makes power and cleans wastewater

April 22, 2025

Researchers at the Indian Institute of Science (IISc) have potentially hit three birds with one stone after their innovative zinc-air battery solves problems in energy, green chemistry, and environmental remediation in one go.

The zinc-air battery developed by the researchers also produces hydrogen peroxide in a low-cost and environmentally friendly way, making it a win-win situation for all, a press release said. 

As the focus shifts to developing greener solutions to meet our energy demand, there has also been an uptick in demand for energy storage options that can store this energy. Lithium-ion batteries (LIBs) have primarily been at the forefront of this change. However, their high upfront costs and limitations in storing large amounts of energy make them unsuitable for large-scale applications. 

Researchers have been working on alternatives to LIBs and found an alternative in zinc-air technology since the major components are much more easily accessible. In this approach, the readily available zinc metal is the anode, while ambient air is the cathode. When the battery discharges, releasing its stored energy, oxygen from the ambient air gets reduced at the cathode, forming either water (H2O) or hydrogen peroxide (H2O2). 

Reengineering the battery for H2O2

A research team led by Aninda Bhattacharyya, a professor at the Solid State and Structural Chemistry Unit (SSCU) at IISc, reengineered a zinc-air battery to ensure that it only produced hydrogen peroxide at the cathode and not water.

“The strategy here is to control the extent of the oxygen reduction reaction,” explained Bhattacharyya in a press release. “If you don’t control it at some level, it will just go and form water.”

The team achieved this using a metal-free catalyst based on carbon. Unlike other catalysts, this catalyst is less expensive. However, some chemical modifications, such as oxygen functional groups, should be used to steer the reaction toward the formation of H2O2.

Conventional hydrogen peroxide synthesis is an expensive process that requires precious metal catalysts and high energy input. Switching to a regular battery makes the process cost-effective as well. 

Breaking down dyes

In their research, the team needed to detect if H2O2 was being produced. Since it is colorless, they used a dye typically used in textile processes. When H2O2 is produced, it breaks down the dye and causes a visible color change. 

“The H2O2 generated will further decompose into various radicals (such as hydroxide and superoxide) – highly raw, reactive organic species – that will eventually degrade the textile dye,” added Asutosh Behera, a PhD student at SSCU who was also involved in the work. This can be used to break down toxic dyes present in wastewater from textile plants.

This degradation has a dual effect. In addition to breaking down the dye, it also helps increase the efficiency of H2O2 production. Since the process only requires zinc and air, which are abundantly available, it also makes it a much cheaper and eco-friendly alternative. 

This is a novel approach where a battery is being used to produce H2O2. But it does not require any special arrangements. “You don’t have to do other things. You have a battery, and you run it,” added Bhattacharyya.