Tuning molecular rigidity to create "porous" ionic liquid electrolytes for safe multivalent batteries.
Abstract
This project will address a critical priority of the U.S. Army: a need to enable new energy storage systems that extend the performance of Army systems well beyond current limits. An emerging goal is to develop batteries that enable soldiers to deploy for more than a week between power resupplies. Achieving this with batteries that are safe remains challenging with lithium-based cells. This research aims to address fundamental questions that promise to enable next-generation electrolytes for batteries based on multivalent metal anodes, which promise to revolutionize the safety and performance of energy storage devices. Batteries are composed of two solid electrodes that are coupled with an electrolyte. Electrolytes function by allowing ionic transport between electrodes, while simultaneously preventing short circuiting. Commercial lithium-ion batteries are typically composed of graphite anodes, metal-oxide cathodes, and organic liquid electrolytes. These electrolytes are flammable and prone to decomposition under harsh conditions, such as those seen in combat environments. Hence, critical failure leads to fires or explosions, and increasing the energy density of batteries based on lithium is likely to exacerbate these risks. Multivalent batteries provide avenues to realize Army energy needs via batteries that are safer than lithium alternatives. Yet, multivalent batteries often use flammable electrolytes translated from lithium-ion cells, which face poor multivalent cycling stability and lead to personnel risk. Advanced electrolytes with increased stability and performance would be a breakthrough for enhancing soldier safety and performance. We propose to launch a program to elucidate how ionic liquid-based electrolytes functionalized with novel “diamondoid� groups could be tuned to stabilize electrode-electrolyte interfaces and selectively enhance multivalent ion transport. More broadly, we aim to reveal new paradigms for tuning molecular assembly to achieve reversible cycling of metal anode batteries. Ionic liquids exhibit properties that are likely to be beneficial for multivalent batteries, including high stability and tunable ion coordination environments. We envision ionic liquids will provide distinct advantages for multivalent batteries, provided that outstanding questions regarding multivalent electrochemistry and ion transport are clarified. This research will bring together multimodal characterization, spectroscopy, and electrochemical analysis to understand multivalent ion transport and chemistry in novel “diamondoid� derived ionic liquids. Bridging the unique self-assembly properties of diamondoids with ionic liquids, we aim to answer fundamental questions surrounding how multivalent ion coordination influences electrochemical device performance and evaluate these materials as novel electrolytes for safe, multivalent batteries. This project will: (1) use calorimetry to establish how multivalent ion doping influences phase behavior in ionic liquids (2) use Raman spectroscopy, NMR spectroscopy, and conductivity studies to understand multivalent ion transport in ionic liquids, and (3) use electrochemical measurements with in situ microscopy to understand how ionic assembly influences battery electrode stability and morphology. The anticipated outcome of this project is identification of new design concepts for multivalent ion transport and electrochemistry in ionic liquids and super-concentrated electrolytes. Such frameworks promise to open the door to safe “porous� organic salt electrolytes that bridge the gap between typical solid and liquid electrolytes to achieve safe, energy dense multivalent batteries.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 17, 2022
- Source ID
- W911NF2310001
Entities
People
- Matthew Gebbie
Organizations
- Army Contracting Command
- United States Army
- University of Wisconsin–Madison