Background
Dr. David Mitlin and his team have developed a multifunctional separator that allows for the stable cycling of anodes and secondary batteries, including metal anodes and metal batteries (MB). Dr. Mitlin is a David Allen Cockrell Endowed Professor at the Walker Department of Mechanical Engineering at UT Austin, with studies focused on energy storage materials/applications, metallurgy, and corrosion. He has published over 175 journal articles, holds 15 U.S. patents, and has eighteen pending patent applications. The majority of his patent work has already been licensed. His qualifications have allowed him to present over 125 keynote/plenary talks at a range of international conferences, and he is an Associate Editor for Sustainable Energy and Fuels. His work has broad applicability in the development of battery technologies, capacitor applications, metal plating techniques, and advanced material design.
Invention
Commercial unfunctionalized-planar PP and PE separators used within the industrial sector provide limited wetting by an electrolyte, do not stabilize the solid-electrolyte interphase (SEI), and cannot prevent dendrite penetration. This behavior results in the formation of dendrites during cycling and limits the safe operation of MB in either a secondary ion reservoir using a metal foil at the anode or in anodeless/anode-free/anode-limited configurations.
To address these MB inefficiencies, materials have been used (e.g., graphenes, various surfactants) to improve the wetting process through a chemical procedure and to block/prevent dendrite formation. These techniques can be expensive, exhibit poor scalability, and can lead to excessive SEI formation at the battery anode. To address these issues, a cheaper, less reactive electrolyte multifunctional separator has been developed, which focuses on stabilizing/improving the performance of the anode/cathode, or both, depending on which side the developed separator is coated. The technology allows for the production of a multifunctional membrane using various thin film deposition techniques (e.g., magnetron sputtering, wet/dry chemistry, chemical/electrochemical deposition, spin coating, spray drying, tape casting, screen printing, thermal, hydrothermal), providing scalability, improved Coulombic efficiency, and suppression of dendrite growth without having to modify the electrolyte or current collector chemistry.
This technology has been demonstrated by fabricating a multifunctional separator using double-coated tape cast reactive micro-scale AlF3 layers on conventional polypropylene and by separator coating fabrication through depositing/bonding powders (e.g., ceramics, nitrides, sulfides, semiconductors, polymers/polymer combinations) on either one/both surfaces of a commercial separator. The developed functional separator coating is based on a single or combination of ionic conducting/electrically insulating solid-state-electrolytes (SSE) (e.g., sulfides, selenides, oxides, borides), which are independent of or combined with an ion-conducting polymer matrix. The resulting coated separator allows the battery to be operated in a liquid-SSE hybrid configuration, increasing MB safety and performance while reducing production costs.
