<p>The increasing global adoption of electric vehicles requires a quantifiable framework to assess the circularity of the lithium-ion battery (Li-ion) value chain. This sector is highly susceptible to supply chain disruptions related to critical mineral availability and shifting geopolitical dynamics. To address these challenges, this study evaluates the circularity of the Spanish EV battery value chain, covering the entire life cycle from design to recycling. A systematic review of existing Circularity Indicators sourced from specialized organizations, governmental bodies, and scientific publications was conducted. These indicators were rigorously categorized and mapped against specific stages of the battery value chain to identify monitoring gaps. Subsequently, a set of five key indicators was selected based on criteria emphasizing data quantifiability and reproducibility. The application of this refined indicator set to the Spanish case study highlights critical bottlenecks and reveals stages with limited circularity monitoring. These findings provide a robust, indicator-based methodology that offers clear guidance for policymakers and industry stakeholders aiming to enhance the sustainability and resilience of the European Li-ion battery supply chain.</p>