String theory meets chemistry: Princeton's new twist on lithium enrichment

No, not that string theory. This is one which relates to actual strings and could assist in the world's transition to greener energy.

Researchers at the Andlinger Center for Energy and the Environment based in the world-renowned Princeton University have developed a method for selectively extracting lithium salts from brine and seawater (https://www.nature.com/articles/s44221-023-00131-3). 

Lithium is a key material required for the energy transition and the amount of lithium the world will require to realise the increase in demand for lithium-ion batteries from 700 GWh in 2022 to 4.7 TWh in 2030 (McKinsey & Company - https://www.mckinsey.com/industries/automotive-and-assembly/our-insights/battery-2030-resilient-sustainable-and-circular) is massive. In order to meet this increase in demand, it is necessary to find better ways of obtaining lithium which are cheaper, more efficient, and more environmentally friendly.

The Princeton researchers have found that porous fibres having a hydrophobic surface and a hydrophilic core and which have been twisted into strings allows for the concentration of lithium and sodium salts at different places along the string. This is achieved by the seawater travelling up the string through the capillary effect, with the water evaporating along the way. This increases the concentration of the salts within the seawater until they begin to crystallise out. The sodium and lithium salts crystallise out at different locations due to their different solubilities and this allows the salts to be concentrated and easily removed for further processing. This system does no rely on any expensive energy input or additional chemicals, and is stated to reduce the amount of land needed by 90% and accelerate evaporation by more than 20 times. Incidentally, crystallisation is growing in visibility as an ever more important area of research for providing battery materials of ever high purity and quality.

The researchers are working on a second generation of the technology and are launching a start-up, PureLi Inc, to commercialise the technology. There will no doubt be a large amount of intellectual property generated based on this technology. It is assumed that a patent application will have been filed already and more should follow as it is often that a greater amount of innovation occurs when an initial concept is put into commercial practice. Everything from the exact materials and configuration of the strings to the process of harvesting the concentrated salts are all potentially open to protection.

Cumulatively, every additional innovation which reduces costs and increases the availability of a key material is going to have a large effect on the cost of the energy transition. Continued innovation in other areas has even beaten out Moore's law on costs, and whilst that may not be possible with energy transition technologies, any reduction in cost will be welcomed and aid in the energy transition.  I look forward to seeing how this technology progresses.