Lithium is widely regarded as a critical and strategic metal that plays an indispensable role in electric vehicles and energy storage technology. This study first provides a dynamic and holistic view on the historical evolution of the global reserve, production, and consumption of lithium. Material flow analysis (MFA) is then used to model the trends of supply, demand, scrap generation, and in-use stocks of lithium from 2020 to 2080. Finally, prospects, challenges, and policy recommendations for urban mining of lithium are discussed. It is shown that, driven by the increasing demand in batteries, the global lithium demand, scraps generation, and in-use stocks will keep fast growing over the next 60 years, and will reach≈1.50, ≈1.15, and ≈18.40 million tons, respectively by 2080. If no new recoverable reserves are found and if lithium recycling rate reaches 100%, then lithium natural reserves would be exhausted in 2080, shifting the future lithium supply from natural minerals to urban minerals. Hence, it is important and urgent to explore the urban mines of lithium, which will have positive influences on trade, resource, energy, and environment. However, there are still many bottlenecks in terms of recycling technologies, economic feasibility, and waste management system to be solved so as to ensure highly efficient and environmental utilization of urban mining of lithium. Several policy recommendations are thus provided.

According to the latest statistics from the United States Geological Survey in 2020, the world has identified 80 million tons of lithium resources, of which 59% are distributed in salt lakes. This article reviews the development status of lithium extraction technology in salt lakes, and summarizes production processes of lithium resources. The adaptability and advantages of various extraction methods are explored with respect to different of magnesium to lithium ratios in salt lakes. It is found that lithium extraction in salt lakes cannot be carried out using a single method and selection of lithium extraction process should be based on different types of salt lakes. The precipitation method in low magnesium to lithium ratio salt lakes has been proven by industrial production while in high magnesium to lithium ratio salt lakes adsorption method is currently the most ideal extraction technology in terms of comprehensive effects, including high adsorption capacity, one-step direct extraction of lithium, high cycle performance and strong stability. Of all these methods, the natural mineral modified adsorption method should be the focus of future industrialization of lithium lake salt extraction.

The high-temperature geothermal water contains abundant lithium resources, and the development and the utilization of the geothermal-type lithium resources are increasingly paid attention around the world. This paper reviews the lithium-rich geothermal resources among the geothermal resources on the Qinghai-Tibet Plateau, and it is concluded that these resources have the following characteristics:(1) strong structural control:the lithium-rich geothermal spots in Southern Tibetan Plateau are often found in the intensely active high-temperature geothermal fields and are distributed on both sides of the Yarlung Zangbo suture zone and its southern part, strongly controlled by north-south trending rifts or grabens formed by E-W extension; (2) good quality:the lithium concentration is up to 239 mg/L; the Mg/Li ratio is extremely low and ranges from 0.03 to 1.48 for most of the lithium-rich geothermal fluid; the Li/TDS value is relatively high and ranges from 0.25%-1.14% (Zhabuye lithium-rich salt lake:0.19%; Salar de Uyuni (Bolivia):0.08-0.31%); the continuous discharge is stable at least for several decades, in some parts reaches the industrial grades (32.74 mg/L:according to the industrial grades of Salt lake brine), and in addition, the elements such as B, Cs, and Rb are rich and can be comprehensively utilized; (3) large scale:according to incomplete statistics, there are at least 16 lithium-rich hot springs with lithium concentration of 19 mg/L or more, and the total discharge of lithium metal is about 4281 tons every year, equivalent to 25686 tons of lithium carbonate, moreover, drilling data show that the depth is still very promising; (4) lack of volcanism (non-volcanic geothermal system); (5) deep origin:the formation of lithium-rich geothermal resources are closely related to the deep crust partially melting caused by the collision of the Indo-Asia continent, the deep molten magma provides a stable heat source for the high-temperature lithium-rich geothermal field and the lithiumrich parent geothermal fluid rushes to the surface to form hot springs along the extensively developed tectonic fault zones in Southern Tibetan Plateau. Therefore, the widely developed high-temperature lithium-rich geothermal resources in the southern Qinghai-Tibet Plateau are valuable and worthy lithium resources. With the continuous advancement of the lithium extraction technologies on lithium-rich geothermal fluid, the lithium resource in Southern Tibetan Plateau is becoming a promising new type of mineral deposit-the geothermal-type lithium deposit and will be effectively exploited.