Electrolytes are central to the performance and safety of redox-flow batteries (RFBs), yet the safety, toxicological profile and life-cycle impacts of both conventional (e.g., vanadium-based) and emerging organic electrolyte systems remain insufficiently characterised. As RFB deployment grows for stationary storage, stakeholders require evidence that electrolyte solutions can be designed and managed in a way that is safe for workers and the environment, including under accident scenarios and at end-of-life. Existing literature and assessment practice largely focus on electrochemical performance, with limited coverage of human toxicity, ecotoxicity, potential nanotoxicity and the implications of production and recycling routes. This creates uncertainty for regulators and industry regarding risk management, governance and standardisation needs. SABATLE addresses these gaps by applying Safe-and-Sustainable-by-Design principles to RFB electrolytes, combining experimental (eco)toxicology, accident-relevant scenarios and life-cycle assessment to identify hazards, hotspots and mitigation options across the value chain.