In this SBIR Phase I effort, Nexceris will advance the product readiness of EnergySafeTM, a disruptive metal-halide energy storage technology that is ideally-suited for fossil asset integration. EnergySafe systems can improve fossil asset utilization and environmental performance while improving grid stability and renewable integration. The proposed project will address the DOE Energy Storage Grand Challenge (ESGC) goals of fostering energy storage solutions that leverage US-developed technology and manufacturing, along with domestically-sourced raw materials, to serve utilities in the US and abroad. The DOE ESGC has identified three critical drivers for future grid-level energy storage solutions. Dynamic electricity supply arises from the rapid growth of US renewable power generation that requires fossil Energy Generating Units (EGUs) to flex output to a greater degree than providing base-load power. Dynamic electricity demand occurs with the daily shift from commercial to residential needs, creating demand peaks that must be met by peaking power generation or energy storage (impossible with current four-hour technologies). Finally, enhanced grid resilience to weather, climate, and cyber threats are necessary to provide longer duration power during blackouts and to assist utilities with asset black-starts. The US grid does not have enough storage to address these three issues, nor can Li-ion batteries fill the gaps. It is essential that new low-cost, scalable, energy storage is co-located and integrated with grid-critical fossil EGUs, to enhance their operational flexibility, efficiency, and environmental impact. EnergySafe is a disruptive intermediate storage duration solution that can address this unmet need. EnergySafe is re-imagining of the sodium metal-chloride (Na-MeCl2) cell. The EnergySafe cell design eliminates the high manufacturing costs associated with thick-walled, cylindrical electrolyte designs of the past, the that have prevented widespread adoption of the technology while retaining its excellent safety and cycle-life, insensitivity to ambient conditions (lower O&M costs), and supply chain, which is based on low- cost, recyclable, US-sourced raw materials. Integrated with fossil EGUs, EnergySafe systems can use waste heat from the fossil asset to enhance its overall efficiency. In Phase I Nexceris will advance the maturity of the EnergySafe cell by tailoring its chemistry and design for EGU-integrated 6-24 hour storage, a critical unmet grid support need. Phase I will culminate in a 20- cell, ~250Wh pack demonstration, to position EnergySafe for larger on-site demonstrations in Phase II. Engagement with utilities will create commercial pull and ensure that EnergySafe is tailored to integrate with fossil EGUs.