Battery Researchers Turn to Seawater to Unlock Iron Alkaline Batteries

In pursuit of batteries that are more sustainable and cheaper, researchers are exploring many different battery chemistries. One battery technology that is gaining traction in the world of academia is iron alkaline batteries, which promise a battery based on more abundant earth materials.

 

Iron alkaline battery technology could reduce use of rare earth materials. Image used courtesy of Adobe Stock

 

Recently, researchers from WPI found a path forward to solving some existing challenges facing iron alkaline batteries. 

 

Iron Alkaline Batteries

Iron alkaline batteries are rechargeable energy storage devices that utilize iron as the primary electrode material and operate in an alkaline electrolyte environment. Unlike traditional lithium-ion batteries that rely on scarce and expensive materials, iron alkaline batteries leverage the abundance of iron, one of the most common elements in the Earth's crust.

One key advantage of iron alkaline batteries is their environmental sustainability. They offer a green solution for large-scale energy storage by utilizing environmentally benign electrolytes and earth-abundant materials like iron and chloride ions. This presents a more sustainable alternative to conventional batteries that often rely on harmful chemicals and scarce resources.

Cost-effectiveness is another crucial aspect of iron alkaline batteries. The use of readily available materials such as iron significantly reduces the production cost, making these batteries an attractive option for grid storage and other large-scale applications where cost efficiency is paramount.

 

Iron Alkaline Battery Challenges

The development of iron alkaline batteries is a promising advancement in energy storage technology, but it faces several challenges that must be addressed to unlock its full potential.

According to the research, one of the primary obstacles is achieving reversible iron redox reactions. Traditional iron-based batteries have struggled with this aspect, which is essential for efficient charging and discharging cycles. The inability to realize reversible redox processes has hindered the widespread implementation of iron-based batteries in modern energy systems.

Material stability is another significant concern. The cycling stability of the battery, or its ability to maintain performance over repeated charge and discharge cycles, must be optimized. While researchers are working on enhancing this stability through innovative redox chemistry, it remains an area that demands further exploration and development.

 

Seawater as a Solution

Recently, WPI researchers sought to address many of these issues by creating rechargeable iron alkaline batteries using chloride ions, an innovative approach that leverages the abundance of both iron and seawater.

The redox reaction of the WPI iron alkaline battery. Image used courtesy of Jagadeesan et al.
 

The team began by addressing one of the primary challenges in iron-based batteries: achieving reversible iron redox reactions. Through extensive experimentation and analysis, the researchers discovered a new redox chemistry that involved the insertion of chloride ions into an iron hydroxide double-layered structure. This process formed a green rust intermediate crystalline material, which played a crucial role in improving the battery's cycling stability and overall performance.

With this knowledge, the researchers developed a small lab-scale prototype of an aqueous battery constructed by using electrodes made mostly from abundant elements like iron oxides and hydroxides. By demonstrating the feasibility of the technology at this scale, they laid the groundwork for potential industrial-scale production.

Beyond finding a chemistry that improved the redox reaction of iron alkaline batteries, this research is important because of its sustainability implications. By designing a battery that is based on chloride ions, which are immensely abundant in the earth’s oceans, the researchers have opened the potential for battery construction that doesn’t require mining or rare earth materials. This not only drives down the cost of batteries but also ensures that we are protecting the environment as batteries become more prominent in daily life.