(64b) Designing Electrolytes for Next-Generation Batteries and Electrolyzers

Electrochemical technologies promise to channel the rapidly falling price of renewable electricity towards the grid, manufacturing, and transportation industries. Among these systems, advanced rechargeable batteries form the foundation of the rapidly expanding EV market and will play a vital role in renewable grid storage. At an industrial level, advanced electrolyzers could be used to produce commodity chemicals from waste CO₂. The advent of these technologies at scale would redefine humanity’s relationship with these industries by aligning profit with sustainability. To realize this promise, however, significant improvements in energy efficiency, device lifetime, and high-power performance must be made. Our work involves the design of electrolyte composition and structure to regulate the (electro)chemical processes that define device performance.

Previously, we investigated the effect on Li⁺ coordination environment on the performance of Li metal batteries under kinetic stress, such as reduced temperatures and high-power charging. Specifically, we found that inducing ion-pairing between Li⁺ and anions reduces the desolvation energy faced by Li⁺ in the electric double-layer. This was probed using experimental and computational means, including the application of free-energy sampling methods. The insights gained from these studies were leveraged to develop electrolytes for both sulfur-type and > 4 V Li metal full batteries capable of cycling down to -60 ^oC and at elevated charging rates.

More recently, we also applied this hybrid computational/experimental methodology to electrolyte design for Zinc batteries. We demonstrate that pairing between Zn²⁺ and halide anions can significantly improve the poor Zn deposition kinetics typically found in organic solvents, while also undercutting the costs of state-of-the-art systems. Deposition from these systems generates polyhedral, textured Zn and exceptional Coulombic efficiencies without any discernable corrosion.

Lastly, we demonstrate that electrolyte composition and structure can also be tuned to enhance CO₂ electrolysis. These electrolytes are based on multivalent cations that are stabilized in the bicarbonate buffer solutions common in CO₂ electrolyzers with electrolyte additives. Electrolytes based on these chemistries show increased electrochemical activity for CO₂ reduction relative to hydrogen evolution. Ab-initio molecular dynamics (AIMD) simulations reveal that these additives polarize H₂O away from the cathode and that multivalent cations induce greater activation of *CO₂ than standard monovalent cations.

This talk showcases a combined experimental and computational approach to electrolyte design for the advancement of electrochemical energy storage and conversion.