power density, and long life-span. [1,2] For example, LIBs have been used extensively in portable electronics, electric vehicles, and large-scale grids storage, which help greatly mitigate the use of fossil fuel and the emission of CO 2 . [3][4][5] Nevertheless, there exists a key issue-the energy stored inside LIBs is renewable, whereas the raw materials from massive mineral mining to fabricate LIBs are not renewable at all. Estimations expect that the LIBs global market is undergoing an enormous growth from 259 to 2500 GWh within the years 2020-2030 by an average of 25.4% per year. [6,7] This indicates a drastically rising demand for raw materials of LIBs, and a drastically rising number of spent LIBs generated due to limited-service life. [8][9][10] Based on this analysis, if a major portion of raw materials to fabricate LIBs could be extracted from spent LIBs instead of from mineral mining, numerous issues including those from economic, environmental, sustainable, and geographical aspects could all be tackled at the same time. It would make LIBs the real crucial factor to unlock renewable energy since the entire process of LIBs including fabrication and employment are all sustainable. [11] Fortunately, there are enough spent LIBs generated each year for us to recycle and extract raw materials/precursors from them. According to a report, by the year 2030, global spent LIBs will reach 11 million tons, where the recycling market will extend to $23.72 billion. [12] Therefore, LIBs recycling is becoming urgent and vital. Several agencies and institutions over the world have already focused on this topic and initiated some efforts. For example, policies for spent LIBs recycling have been established in some countries like the US, Germany, Japan, and China. [6] In addition, ReCell Center led by Argonne National Laboratory has set core principles for sustainable recycling, including the design of novel recyclability, direct recycling/ repair/regeneration, and recovery of other high-value-added components. [13] In this review, we systematically summarize and assess LIBs recycling from the perspectives of necessity (such as economy, environment, sustainability, and geography), current (such as pyrometallurgical and hydrometallurgical methods), and novel (such as direct regeneration/repair methods) recycling technologies. We also discuss the viability of implementing the current recycling technologies in next-generation Li-based batteries.The overuse and exploitation of fossil fuels has triggered the energy crisis and caused tremendous issues for the society. Lithium-ion batteries (LIBs), as one of the most important renewable energy storage technologies, have experienced booming progress, especially with the drastic growth of electric vehicles. To avoid massive mineral mining and the opening of new mines, battery recycling to extract valuable species from spent LIBs is essential for the development of renewable energy. Therefore, LIBs recycling needs to be widely promoted/ applied and the advanced recycling technolog...