In recent years, the demand for lithium-ion-batteries (LIBs) for electric vehicles and fixed power storage has experienced explosive growth, resulting in a substantial increase in worldwide lithium consumption. To meet the growing demand, lithium-bearing minerals and lithium recycling from end-of-life (EOL) LIBs have attracted much attention. However, the lithium extraction and recycling processes bring a challenge: the production of a significant amount of sodium sulfate. Sodium sulfate, a white crystalline type of salt, is a seemingly innocuous byproduct. It is used in various industries, from manufacturing detergents and textiles to glass and paper. However, when it is produced in bulk as a by-product of battery-grade lithium hydroxide, lithium carbonate, and pCAM, its limited application may be overwhelmed by the disposal cost. In this article, the hydrometallurgical processes for extraction of lithium from ores, brine, and battery recycling with sodium sulfate as a by-product are discussed. Alternative and environment-friendly processes to valorize sodium sulfate are reviewed.