Shrimp shells to produce electrodes for large storage batteries

A project by Spanish researchers and other collaborators from the Massachusetts Institute of Technology (MIT) suggests the use of chitin from shrimp shells to produce electrodes for vanadium flow batteries. The results of the work have recently been published in ACS Sustainable Chemistry and Engineering.

“We propose to produce these vanadium flux battery electrodes from chitin, a shrimp shell material, which, in addition to carbon, contains nitrogen,” says Francisco Martín-Martínez, a chemical engineer and one of the authors. “Vanadium redox flow batteries, unlike lithium batteries used in the automotive industry, do not provide a high energy density, but provide a large volume of energy storage at low cost, making them ideal for storing energy from renewable sources such as solar and wind power, whose energy production is intermittent. “

Martín-Martínez, an expert in the development of bioinspired materials, points out that carbon electrodes are generally used to facilitate the flow of electrons from one side of the battery to the other: “We have produced these electrodes from chitin, a material from the shrimp shells. Chitin is a polysaccharide, similar to cellulose, found in the exoskeleton of crustaceans and insects. “

Improved performance

The peculiarity of chitin, he says, “is that, in addition to carbon, it also contains nitrogen, which is incorporated into the structure of the electrode during the production process, improving its performance.” This parameter has been characterized in detail by the authors in the article.

In fact, the team has demonstrated the benefits of nitrogen in the chemical structure of the electrode, where it facilitates the transfer of electrons between the vanadium ions. “Obviously, there are carbon electrodes that can produce better performance, but the key to this project is to produce such electrodes from a waste material, in this case, the chitin from shrimp shells,” says Martín-Martínez. He emphasizes its good performance and the low cost and sustainability of the starting material.

Currently, electrodes of this type are mainly made of carbonized polyacrylonitrile, a synthetic polymer, so their production from a waste product such as chitin is, in Martín-Martínez’s opinion, “a more sustainable alternative” .

Martín-Martínez says: “These electrodes of shrimp waste could also be applied in supercapacitors, electrochemical devices that provide a very high energy density and even in desalination processes, although we have focused on redox flow vanadium batteries.”