Advanced Multifunctional Battery Separators for Novel Liquid Electrolytes

There exists an urgent need for advanced ion-selective membranes to enable new energy storage chemistries and architectures (beyond lithium ion batteries, for example, sodium ion batteries) Some novel liquid electrolytes, such as highly concentrated ionic liquids and water-in-salt electrolytes, have shown great potential to improve safety, rate performance and cycling stability of rechargeable batteries with different chemistries; however, due to the varying hydrophobic / hydrophilic nature and rapidly changing viscosity (as a function of temperature) of highly concentrated electrolytes, the choice of a suitable separator for these novel liquid electrolytes is extremely challenging The incompatibility or poor wettability with commercial separators is a primary barrier to apply novel liquid electrolytes into practical batteries For novel electrolytes to reach their full potential in practical batteries, a new type of separator is needed Our proposed separator aims to fulfill this need In this project, TalosTech LLC (Talos) and California Institute of Technology (Caltech) propose to develop a flexible and multi-functional polymer/ceramic composite membrane with vertically aligned hierarchical pores as a new type of separators The new separator has excellent wettability with highly concentrated electrolytes and provides a short working-ion transportation path for high ionic conductance The novel multifunctional membrane will be fabricated by a facile bidirectional freeze-casting process and tailor-made for novel liquid electrolytes, with the following features: (1) vertically aligned submicron pores designed to minimize pore tortuosity, and therefore, increased ionic conductance, (2) polymer/ceramic composite designed to enhance separator wettability, and (3) a cost-effective and scalable roll-to-roll manufacturing process This composite membrane separator will be outperforming to other existing commercial separators for new battery chemistries using novel liquid electrolytes