RWTH Aachen expands M5Bat with Germany's largest sodium-ion research storage

RWTH Aachen University has significantly expanded its M5Bat research battery storage system at the Institute for Power Electronics and Electrical Drives (ISEA). The goal is to investigate new battery technologies under real market and grid conditions and to evaluate their industrial applicability. The core of the expansion is a **sodium-ion battery container with 750 kVA power and 1.5 MWh capacity**, which the university states is currently the largest sodium-ion research storage facility in Germany. Sodium-ion batteries are considered a promising alternative to lithium-ion systems, especially for stationary applications, as sodium is widely available and can offer long-term cost advantages. Additionally, another battery system with **125 kVA power and 250 kWh capacity** has been integrated, based on **semi-solid-state LFP cells**. This technology combines the proven lithium iron phosphate chemistry with a semi-solid electrolyte, which is intended to enable higher safety and improved thermal stability. The new systems were procured by RWTH and are scheduled **to be commissioned in spring 2026**. In ongoing operation, M5Bat is used together with an energy partner to deploy the storage units in various market segments, including electricity trading and balancing power markets. The research aims to analyze the **performance, efficiency, aging behavior, and economic viability** of the battery technologies under realistic load profiles. The data obtained is intended to help industry and grid operators reduce technological risks and make informed decisions for the deployment of new battery systems. With this expansion, RWTH Aachen strengthens its role as a central research platform for innovative energy storage solutions and contributes to the further development of sustainable and resilient energy systems