[SMM Analysis] Chinese Scholars Make Progress in Interface Photothermal Salt Lake Lithium Extraction Technology

With the support of the National Natural Science Foundation of China, Professor Zhu Jia from Nanjing University and his collaborators have made progress in the green development of salt lake lithium resources. The related results, titled "Solar transpiration–powered lithium extraction and storage," were published online in Science on September 27, 2024.

As a strategic key metal in the global energy transition, lithium is widely used in electric vehicle batteries and renewable energy storage systems. Salt lake lithium mines are the main source of global lithium resources. For example, China’s Qinghai-Tibet Plateau is rich in salt lake lithium resources. However, due to the complex chemical conditions of salt lakes and strict environmental protection requirements, large-scale mining has not yet been realized, becoming a bottleneck problem in the development of China's salt lake lithium resources. Therefore, developing new green, environmentally friendly, and sustainable salt lake lithium extraction technologies is key to solving this problem and has significant economic value and strategic importance.

Professor Zhu Jia's team drew inspiration from the "selective absorption-storage-release" mechanism of halophyte plants to develop interface photothermal salt lake lithium extraction materials and devices (STLES, Fig. A-B). The research team used an aluminum-based plasmonic evaporator with efficient photothermal conversion (Fig. C) as the interface photothermal layer to achieve rapid water evaporation and generate ultra-high capillary pressure in nanometer channels. At the same time, hydrophilic porous silica ceramics were used as the lithium chemicals storage layer (Fig. D), and polyamide nanofiltration membranes were used as the ion sieving layer (Fig. E) to achieve selective extraction and storage of lithium ions. During the operation of the device, water and lithium chemicals pass through the ion sieving layer into the storage layer under the action of capillary pressure, and then are collected through the water circulation system, completing the regeneration of the device. The research results show that this technology can efficiently extract lithium from diluted salt lake brine and maintain excellent stability in continuous operation for over 500 hours, demonstrating great potential for long-term application. In addition, this technology has strong compatibility, and by optimizing the ion sieving layer and adopting a multi-stage lithium extraction process, lithium selectivity was increased by 6 times and 40 times, respectively. The modular design also allows lithium production to increase linearly with the number of modules, further enhancing the practicality and scalability of this technology.

This work achieves effective extraction of lithium resources from salt lakes through interface photothermal salt lake lithium extraction technology, which is expected to promote the green development of China's Qinghai-Tibet salt lake lithium resources, reduce China's dependence on imported lithium ore, and ensure the secure supply of China's strategic key metal lithium.