Researchers have designed a groundbreaking electrochemical reactor that extracts lithium from natural brine solutions. This innovation presents a promising solution to meet the rising demand for lithium, particularly used in rechargeables batteries.
A research team from Rice University, guided by Lisa Biswal and Haotian Wang, has introduced a novel electrochemical reactor aimed at extracting lithium from natural brine solutions. This advancement, shared in the Proceedings of the National Academy of Sciences, holds considerable promise for renewable energy storage and electric vehicle applications.
Lithium is essential for batteries used in renewable energy storage and electric vehicles. However, conventional lithium extraction techniques encounter various difficulties, such as excessive energy consumption and complications in separating lithium from other elements. Natural brines—salty waters located in geothermal settings—are becoming preferred sources of lithium, as traditional ore extraction is becoming more challenging and costly. Nonetheless, these brines also contain ions like sodium, potassium, magnesium, and calcium, which closely resemble lithium in terms of chemical properties, making separation a complex task. Because lithium and these other ions have similar ionic sizes and charges, classic separation methods often lack the necessary selectivity, resulting in higher energy use and chemical waste. Additionally, the high levels of chloride ions in brines can produce harmful chlorine gas during electrochemical processes, leading to added safety issues in extraction.
The engineering team at Rice has addressed these challenges by creating a unique three-chamber electrochemical reactor that enhances the selectivity and efficiency of lithium extraction from brines. In contrast to conventional techniques, this innovative reactor includes a middle chamber filled with a porous solid electrolyte, which effectively controls ion flow while preventing unwanted chemical reactions as brine flows through. The cation exchange membrane functions as a barrier to chlorides, stopping them from reaching the electrode area where they could generate chlorine gas, thus reducing hazardous by-products. The core technology enabling precise lithium extraction is the specialized lithium-ion conductive glass ceramic (LICGC) membrane located on the electrolyzer’s other side, which selectively permits lithium to move through while blocking other ions. The LICGC membrane’s exceptional ionic conductivity and selectivity are vital for maintaining high efficiency by significantly mitigating interference from other ions found in natural brines, such as potassium, magnesium, and calcium. Although LICGC membranes are typically employed in solid-state lithium-ion batteries, this method of selective lithium extraction showcases a novel and effective application of the material’s advanced ionic conductivity and selectivity.
“Our technique achieves not only high lithium purity but also reduces the environmental risks associated with conventional extraction methods,” said Yuge Feng, the study’s lead author and a graduate student in the Biswal lab. “The reactor we developed aims to lessen by-product formation and enhance lithium selectivity.”
The reactor has demonstrated exceptional results, achieving a lithium purity level of 97.5%. This indicates that the system can successfully isolate lithium from other ions in the brine, which is crucial for producing high-quality lithium hydroxide, a key component in battery production. Moreover, the new reactor design significantly cut down the generation of chlorine gas, enhancing safety and sustainability in the process. The researchers believe this could revolutionize lithium extraction from difficult sources like geothermal brines.
“This reactor could signify a significant advancement in making lithium extraction more efficient and environmentally friendly,” noted Biswal, the William M. McCardell Professor in Chemical Engineering and co-corresponding author alongside Wang.
Another important discovery was related to the reactor’s stability over time. The team found that sodium ions tended to accumulate on the LICGC membrane surface, obstructing lithium transport and increasing energy usage, unlike potassium, magnesium, or calcium. While this buildup can compromise lithium extraction efficiency, the researchers have proposed strategies to alleviate the problem, such as reducing current levels, and recommend subsequent studies examine surface coatings or current pulsing to optimize the reactor further.
This research indicates a cleaner, more efficient, and potentially quicker method for extracting lithium from geothermal brines, representing a crucial advancement in securing a reliable lithium supply for renewable energy technologies.
“Our field has long battled the inefficiencies and environmental consequences of lithium extraction,” said Wang, an associate professor of chemical and biomolecular engineering. “This reactor highlights the effective combination of fundamental science and engineering creativity to tackle real-world challenges.”
Contributors from Rice’s Department of Chemical and Biomolecular Engineering include graduate students Feng, Yoon Park, Chang Qiu, Feng-Yang Chen, Peng Zhu, and Quan Nguyen. Postdoctoral researchers from the same department are Shaoyun Hao, Zhiwei Fang, Xiao Zhang, and Shoukun Zhang. Tanguy Terlier serves as the director of surface and interface characterization at the SIMS Laboratory within Rice’s Shared Equipment Authority.
