Exploring Radiant Sources for Energy Storage and Transfer: The Photon Battery

While electrochemical batteries are today’s preferred mode of energy storage, there are materials capable of directly storing radiant energy, such as phosphorescent materials. These materials store excited charged particles in the form of metastable electrons which recombine to emit photons, or light, at a later time. Although these materials do not presently possess equal or greater energy densities than electrochemical battery technologies, they offer potential benefits which may offset traditional capacity costs by providing longer useful lifetimes, high specific power charging capability, and using nonflammable COTS components. Nimbus Engineering proposes to further develop their patented phosphor-based technology, the Photon Battery, which uses strontium aluminate (SrAl2O4) [phosphor] as a means of storing radiant energy and photovoltaic (PV) cells as a means of discharging said energy. Prototype systems have demonstrated the concept of radiant energy storage, however, with low efficiency and low power output relative to electrochemical batteries of similar mass and volume. The proposed work seeks to improve upon mechanical designs such that the volumetric footprint is decreased, and energy capacity is increased, therefore increasing the system’s energy density (Wh/L). Additionally, this effort seeks to improve the photoluminescent properties of strontium aluminate doped with europium and dysprosium. The main considerations in achieving the proposed improvements include: (1) decoupling the light source from the edges of the device such that any external light source can theoretically optically pump the system from near or far, (2) develop phosphor deposition techniques since the final product requires high uniformity and phosphor-adherence methods so as to increase excitation uniformity and maximize PV voltage response, (3) replication of recent experimental results which indicate strontium aluminate’s photoluminescent properties can be enhanced such that the intensity of emitted photons is increased, or the emission persistence is longer, or both, using varying dopants and dopant ratios, and (4) to the greatest extend possible, all non-energy-storing mass within the system must be eliminated in order to achieve optimal system energy densities.