Sodium metal chloride batteries are the latest generation of batteries introduced into the market for electric vehicles, mainly for public transport. Due to their high scalability and flexibility in assembling different modules and system sizes, several products are currently available in a wide variety of applications. Recyclability, zero gas emission, stable chemical reactions, zero maintenance during operating life, no risk of explosion even when exposed to fire, make them one of the best choices for the oil & gas industry, renewables power generation, transmission and distribution of energy, communications, railways and other industrial uses.
In the framework of the SOLSTICE project (European Union’s Horizon 2020, grant agreement No. 963599, www.solstice-battery.eu), an innovative Na/Zn chloride battery, based on the ZEBRA® technology, will be developed to provide safe and reliable power generation for low-cost stationary storage. The Na batteries require hermetic and corrosion resistant seals to provide containment for the molten materials and electrical isolation between the battery case and cathode. The development of a reliable sealing process is of tremendous importance because it guarantees a long lifetime and safe operation. The key issues to be focused on for this application are the corrosive environment (Na liquid, vapor, and NaAlZn) at 300°C and the long-term durability.
 In this work, different glass-based systems have been considered as potential candidates for ensuring a proper sealing between the β-alumina electrolyte and the α-alumina collar, to guarantee an appropriate separation between the cathode and anode compartments. A systematic characterization of a silica-based and a silica-free glass, both with Al2O3 powder added to increase corrosion resistance and thermo-mechanically compatibility with α and β-alumina substrates, was performed. Furthermore, morphological and compositional analyses of the joints were carried out by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS).
On the other hand, water-based ink formulations containing glass particles are investigated in terms of rheological properties and printability by using robocasting, which is an easily adaptable and low-cost additive manufacturing technique, avoiding the use of organic solvents and minimizing the number of wastes in the whole process.