AbstractLithium-ion batteries are widely used in consumer devices and electric vehicles due to their higher energy density, output, and extended cycle durability. Heavy metals, polymers, and toxic organic electrolytes found in used lithium batteries pose serious environmental concerns. A typical lithium-ion battery is made up of a variety of metals, including cobalt (5%–20%), nickel (5%–10%), lithium (5%–7%), and copper (6%–12%). Lithium and cobalt, in particular, face severe supply limitations, resulting in a threefold spike in lithium prices and a fourfold increase in cobalt prices between 2016 and 2018. The economic and environmental ramifications clearly show that effective and ecologically friendly lithium-ion battery recycling is no longer a choice for manufacturers but rather a must. Although various battery-recycling methods have made advances, the process’s economic feasibility and carbon footprint will be determined by the individual battery chemistry. The three most common recycling processes utilized in used batteries recycling are hydrometallurgy, pyrometallurgy, and electrometallurgy. According to the findings, the leaching process is the key to an efficient, cost-effective, and long-term closed-loop process for lithium-ion batteries. The current favored approach for leaching in the battery recovery process is acid leaching. The acid leaching method, which uses inorganic acids like H2SO4 and HCl as leaching solvents, produces high leaching rates and efficiency but at the cost of increased solvent prices and secondary pollution. Organic acid leaching (citric acid, formic acid, and so on) is gaining popularity due to its environmental friendliness and equivalent leaching effectiveness to inorganic leaching. Bioleaching is a new type of leaching that uses microorganisms and is currently in the early stages of development. Ammonia’s chelating properties make it an excellent leaching solvent for targeted metal ion separation, and it may also be easily removed from leached solution by simple distillation. As a result, ammoniacal leaching offers a lot of potentials for lithium-ion battery closed-loop recycling. Understanding how materials and solutions interact provides the foundation for high leaching efficiency and tailored metal selectivity. We outline the closed-loop recycling techniques for lithium-ion batteries in this study, with an emphasis on the problems and technical advancements.