Composite Polymer Electrolytes for Magnesium Batteries

This dissertation presents the development of composite polymer electrolytes for magnesium batteries. Magnesium (Mg) batteries refer to a class of post-lithium-ion batteries that are slated to complement the role of lithium-ion batteries. With the high volumetric specific capacity of Mg-metal anode and its added safety aspects, it serves as an ideal candidate for developing the next generation battery system. Despite having been realized more than a decade ago, the Mg battery system needs significant improvements in the performance of the electrolyte and the cathode before it can be commercialized. The electrolytes developed to date do not have adequate voltage stabilities, and the cathodes have limited specific capacities. The limitation in electrolytes is particularly concerning because it also hinders the experimental identification of high-voltage cathode materials. The ones that do possess acceptable voltage stabilities have further complications such as (i) the need for a complicated synthesis procedure, (ii) the use of flammable organic solvents, and (iii) incompatibility with Mg-metal anode. Considering these difficulties, efforts were simultaneously put into developing polymer electrolytes. By eliminating flammable, passivating solvents from the electrolyte, it is possible to render the electrolyte compatible with Mg-metal anode and make it safer. However, the polymer electrolytes developed so far have shown only limited cyclability with Mg-metal anode. This work is aimed at developing a Mg-ion conducting polymer electrolyte that exhibits good cyclability with Mg-metal anode at room temperature in addition to a high ionic conductivity.