טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentAssael Cohen
SubjectMiniaturization of Thermal Batteries by Tape Casting
Technology
DepartmentDepartment of Chemical Engineering
Supervisors Full Professors Grader Gideon
Dr. Shter Gennady


Abstract

Thermal Batteries (TB) are pyrotechnically activated molten salts electrolyte primary batteries. Due to their high power density, fast activation time and high reliability, they are widely used in military and aerospace applications. The current demand is to minimize the size and weight of TB, which consists of a stack of cells, each built from a cathode, an electrolyte, an anode and heat disks. The current technology is based on pressing powders into disk shaped cell elements. Pressing technology is quite expensive and restricts the lower limit of size and weight of the battery. This method is also strongly limited by powder size and morphology.

The suggested alternative technology developed in this work, is tape casting (TC), since it can bypass the limitations above. TC is a process in which slurry of a powder, dispersed in a solvent/organic binder solution, is cast on a flat surface. Dried green tape is heated to remove the binder and to sinter the particles. It enables manufacturing of large-area films with a variable thickness (25-1300 μm).

The main goal of this work was to develop a tape casting process to miniaturize thermal batteries elements. This research was mainly focused on developing a stable slurry with the right additives, finding the optimal parameters and conditions of casting, drying and heat treatment. In addition, the effect of powder morphology on the final product properties was detailed investigated. In overall, three different processes for the cathode, separator, and anode casting were developed in the framework of this project.

    We succeeded in developing a cathode and separator that demonstrated promising discharge results. The disks thickness was reduced in half compared to the current products prepared by pressing. The anode was successfully prepared   in the form of green tape and its final heat treatment should be conducted in the dry rooms.

  In conclusion, the feasibility of tape-casting technology to produce thin elements for miniature thermal batteries was demonstrated.