The exponential rise in lithium-ion battery (LIB) consumption driven by electric vehicles, portable electronics, and renewable energy storage has led to a parallel surge in spent LIB waste, posing serious environmental, economic, and geopolitical challenges. Effective recovery of critical materials such as lithium, cobalt, nickel, and manganese ensures supply chain resilience and enables circular economy pathways. Conventional recycling approaches, particularly pyrometallurgical and hydrometallurgical methods, are often energy-intensive and environmentally taxing due to their reliance on fossil fuels and complex chemical treatments. This chapter explores an emerging sustainable alternative: the use of concentrated solar thermal (CST) systems for the green recovery of critical materials from spent lithium batteries. The discussion begins with an overview of LIB chemistries and CST system configurations, emphasizing their compatibility for high- and ultra-high-temperature thermochemical processing. Various solar-assisted recovery techniques are examined, including solar-driven roasting, calcination, and hybrid leaching, with a focus on their process parameters, recovery efficiencies, and environmental performance. Case studies, pilot-scale demonstrations, and comparative energy assessments are presented to evaluate the feasibility of CST-integrated recycling routes. The chapter addresses current barriers, such as process control, thermal stability, and policy gaps, and offers insights into future integration strategies involving smart monitoring, AI-based optimization, and co-location with renewable energy hubs. The chapter concludes by positioning solar thermal recycling as a promising, low-carbon solution for sustainable critical material recovery in a resource-constrained world.