With 33 years of Industrial R&D experience and expertise, he is a visionary leader in innovative Research and Development driving New Product Development, process improvement, beneficiation of minerals, wealth from waste and decarbonisation efforts in aluminium industry. His leadership sparks open innovation and effective collaborations that translates research into real-world applications and sustainable business solutions. With a rich background encompassing upstream and downstream aluminium processes, process intensification by modelling and simulation, valorisation of waste by chemical processing, Dr. Chatterjee is an eminent force in the field.

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There is an ever growing demand of energy and with the restriction of use of fossil fuels, electro-chemical devices are emerging as reliable solution. Though Li ion and Li polymer batteries have largest market share among the rechargeable energy storage for wide range of applications, metal air batteries in general are also considered as a replacement for lithium-ion batteries. The global metal air battery market size was valued at ~ USD 500 million in 2023 and is projected to be worth USD 526.09 million in 2024 and may reach USD more than 1,200 million by 2032, at a CAGR of 11.65% during the forecast period.

Aluminium Air Battery:

Al-air batteries with high energy density ~ 8.0 kWh/kg; specific capacity of about 2.9 A h g−1 and open circuit voltage of approximately 2.7 V offer big promise to beat the performance of Li ion Battery which is thus far having the largest market share in electrochemical devices. Al-air batteries have potential for use in long-range electric vehicles (EVs), consumer electronics, maritime uses, and grid energy storage. Al-air-powered electric car could have a driving range of around 1600 km with about 25 kg of Aluminium and 90 kg of the entire battery. Thus, a vehicle with Al-air battery has the potential to drive 4 to 5 times longer distances which adequately justifies why the Researchers should intensify efforts to build complete eco system of a reliable Battery Device backed by supply chain to recharge the same by way of Anode replenishment in shortest possible time. Generally, the energy densities of LIBs are in a range of 200–250 W h kg1, which is much lower than that of gasoline of 1700 W h kg1.

Global market of Al-Air battery was US $ 5 million in 2021. It is estimated to grow at CAGR ~ 8% during next one decade. Automotive was the largest market in 2021.

There are two following segments which will emerge large consumers for this type of battery.

EV segment: Li ion dominated EV market might witness entry of alternative green Energy Supply Device like Al-air Battery. Al-air battery can provide an overall technically superior alternative in Li ion dominated EV market segment. Its light weight, higher energy density and longer vehicle running are distinct advantages. However, since Aluminium anode is consumed in the process, retrofitting of the same has to be planned in an automated well designed Service station. At least, this can be considered far less challenging than the anticipated environmental concerns.

Stationary segment- Renewable Energy Backup: There is a possibility of surge in demand for renewable energy segments like wind and Solar power. Al-air battery can be a very effective solution for the stability of the grid during the non-functional time of the Energy sources.

Construction and reactions of Al-air battery:

The Al-air battery is fabricated of an anode made up of pure Aluminium or a suitable alloy, an air cathode, and a electrolyte, a typical electrolyte is a aqueous alkaline solution such as sodium hydroxide (NaOH) or potassium hydroxide (KOH) or sometimes sodium chloride (NaCl) solutions. The desirable electrochemical reactions at the electrodes are listed below

Anode: Al ®Al 3+ +3e

Cathode: O2+2H2 O +4e-®4OH

Overall: 4Al +3O2 +6H2O ®4Al(OH)3

Technology issues to be resolved:

However, the conventional aqueous electrolyte-based aluminium-air battery with bulky liquid storage, parasitic corrosion of aluminium in contact with the electrolyte, and formation of a passive oxide or hydroxide layer has precluded its widespread application. In order to achieve successful simplification and cost-effectiveness, a novel idea of a polypropylene-based aluminium-air battery is proposed.

For normal Al–air batteries, several issues exist, including: (1) the formation of by-products such as Al2O3 and Al(OH)3 on electrode surfaces that can suppress Al–air battery electrochemical reactions, (2) hydrogen evolution resulting from parasitic corrosion reactions on Al surfaces and (3) the formation of corrosion products such as Al(OH)4 − and Al(OH)3. This parasitic chemical side reaction can be expressed as:

Al + 3H2O → Al(OH)3 + 3∕2H2

and can induce passivation and corrosion on Al anode surfaces to further suppress electrochemical reactions and often occurs in electrodes containing aqueous electrolytes. Furthermore, this passivation film is mainly composed of Al2O3 and Al(OH)3 and can induce positive shifts in the corrosion potential of Al electrodes, which can cause failure in corresponding Al–air batteries. Current research is focussed on the design of the Aluminium Anode plate by a suitable alloy development and also the passivation of the anode plate to prevent corrosion reactions. Design of electrolyte system and separator are also active areas of investigation.

Technology focus:

1. Aluminium alloy development for anode: This is a very important area for intense research. Suitable alloy to prevent the parasitic reactions is essential. This will help enhance the energy density to a great extent.
2. Anode coating: Suitable passive coating of anode plate will enhance the performance of the Anode by inhibiting the undesired reactions of electrolyte with Aluminium
3. Air cathode design: This is one of the crucial components for superior electrochemical performance and offers by way of preferential permeability of oxygen.
4. Design of electrolyte performance: Suitability of alkaline electrolyte over neutral or acidic is well understood. However recovery of Al(OH)3 from the spent electrolyte is very important for further study.

Thus to summarise here are key advantages and disadvantages of Al-air battery:

• Energy density: Al-air batteries have one of the highest energy densities of any battery, up to five to ten times higher than lithium-ion batteries.
• Lightweight: The aluminium anode is very light, and the cathode is made of a wire mesh and membrane layer.
• Inexpensive: The aluminium anode is inexpensive.
• Non-toxic: The aluminium anode is non-toxic and safe.
• Applications: Al-air batteries have potential for use in long-range electric vehicles (EVs), consumer electronics, maritime uses, and grid energy storage. For example, an Al-air-powered electric car could have a driving range of around 1000 miles (1600 km) with only 55 lb (25 kg) of aluminium.

However, Al-air batteries also have some limitations, including:

• Aluminium Anode gets consumed which means it has to be replaced by a New One in Service Station
• By-products: When using traditional electrolytes, there can be problems with removing by-products.
• Rechargeability: Al-air batteries are not rechargeable, anode to be replaced along with electrolyte
• Corrosion: Even when they are not in use, there are corrosion reactions that need to be addressed to prevent consumption of Anodes.

India can become a significant producer and market for this energy system since we have large primary Aluminium manufacturing capacity. Primary aluminium companies utilise the big opportunity next 2 to 3 years. Scientific and Engineering talent required for design and Development of this wonderful electrochemical device is very much possible for us. Considering the current landscape of thrust on Decarbonisation measures, technology, human resources, demand and supply- Aluminium air battery is an appropriate field to deploy resources and time for next 2 to 3 years.