This Small Business Innovation Research (SBIR) Phase I project is on the development of a planar, highly compact, sodium-beta rechargeable battery using sodium-ion conducting beta alumina solid electrolyte disc (Na-BASE) sandwiched between a liquid sodium and a nickel chloride salt, (p-ZEBRA battery). All commercially available sodium-beta battery technologies use thick Na-BASE tubes, resulting in relatively low specific energy densities and large thermal masses that inhibit fast thermal cycling. In this project, highly performing planar Na-BASE discs, possessing high strength and high resistance to moisture and CO2 attack, will be developed and manufactured using a patented vapor phase process. The p- ZEBRA battery allows operation over a wide temperature range from 200ºC to 400ºC, delivering the integration and operation flexibility suitable for intermittent renewable energy storage applications (wind, solar power and geothermal) with high round-trip efficiencies, or thermal integration with internal-combustion engines or solid oxide fuel cells (SOFCs) for plug-in hybrid electric vehicle (PHEV) applications with extended driving range.
The broader/commercial impacts of this research are to provide a low cost, highly reliable electric energy storage system, which integrates with a broad spectrum of power generation systems. It includes the fast market penetration renewable energy power systems that mitigate grid transient issues, and gasoline internal-combustion engines or advanced SOFCs for PHEV with extended driving distances. The successful development and deployment of the proposed p-ZEBRA battery technology will assist the US with building critical new industry and reinstating US leadership in large-scale electric energy storages.
Intellectual Merit Sodium-beta batteries, including the sodium-sulfur battery and the sodium-metal halide battery, have been showing great promise when integrated into solar and wind farms as electrical energy storage devices. The commercially available, state-of-the-art sodium-beta batteries are all constructed with a tubular sodium-ion conducting beta"-alumina-solid-electrolyte (BASE) having a wall thickness of over 2 millimeters, which is due to the nature of low fracture strength of the BASE manufactured by conventional processes. The primary objective of this SBIR Phase I program was to overcome the limitations of the current sodium-beta battery technologies by the development of an advanced battery with a thin planar architecture. Over the course of this Phase I project, a unique "unibody" design for the planar sodium-metal halide battery was developed with merits of being highly compact and mechanically & chemically stable. Key battery components were designed and manufactured with well-matched coefficients of thermal expansion. BASE discs with a typical thickness less than 1.2 millimeters were fabricated using the patented vapor phase process proprietary to Materials & Systems Research, Inc. Boiling tests of discs over 1,440 hours (60 days) demonstrated that the BASE fabricated by MSRI’s process possessed exceptional mechanical & chemical integrity and excellent resistance to both moisture and carbon dioxide attack, which are the greatest challenges to the BASE fabricated by the conventional processes. Battery construction processes were developed and implemented successfully, and the resulting battery cells showed no sign of leakage after being exposed to Helium pressurized to 3 absolute atmospheres over 150 hours. Proof-of-concept tests of prototype planar cells successfully demonstrated excellent battery performance with capacity as high as 775 mAh when cycled at 1/2C rates (equivalent to 400 mA or 100 mA/cm2). The planar battery cells also showed excellent freeze-thaw survival after undergoing 23 thermal cycles at a ramp rate of 720ºC/h. These Phase I results empower further development of a compact cost-effective battery system for energy storage applications. Broader Impacts The concept of planar sodium-metal halide batteries was developed and demonstrated successfully in this Phase I project. The unique battery design and successful development of processes enable such a compact and reliable energy storage device to be integrated cost-effectively with a broad spectrum of power generation systems, including fast market penetration of renewable energy power systems (which mitigate grid transient issues and national energy dependency issues) and gasoline internal-combustion engines or advanced fuel cell systems for Plug-in Hybrid Electric Vehicles with extended driving distances. The successful development and deployment of the planar sodium-metal halide battery technology will also assist the US in building critical new industry and reinstating US leadership in large-scale electrical energy storage systems.
