(412a) Chemistry Design and Understanding of Polymers for Lithium Batteries

Lithium-based batteries are ubiquitous in modern energy supply systems. There is a high demand for safer, longer-lasting, and higher energy density batteries. Polymers comprise many components in the batteries, including electrolytes, electrode coatings, active material binders, and separators. This talk focuses on understanding the interactions among ions, solvents, and polymers in the battery system, as well as tuning those interactions through molecular-scale design.

SAFEty for Li-ion Batteries:
The volatile and flammable nature of the existing electrolyte in Li-ion batteries remains a safety challenge. The first part of the talk introduces a new class of electrolytes called SAFE (Solvent-Anchored non-Flammable Electrolyte)¹. As a liquid-state electrolyte, SAFE is non-flammable, yet it is just as conductive as today's electrolytes. It addresses the long-standing challenge of creating a non-flammable electrolyte that is functional and practically manufacturable.

Coatings for Li-metal Batteries:
Replacing the graphitic anode in Li-ion batteries, the Li-metal battery is widely regarded as the next-generation energy storage device due to its high energy density. However, its stable long-term operation is hindered by the unstable interface between the Li-metal electrode and the electrolyte. Specifically, Li reacts with the electrolyte to form an unstable solid-electrolyte interphase (SEI) layer. This leads to irregular Li deposition, capacity fading, and even battery shorting and failure. The second part of this talk covers polymer coating designs for Li-metal electrodes. These coatings stabilize the Li-electrolyte interface by maintaining uniform coverage², homogenizing charge distribution^{3, 4}, and improving SEI chemistry⁵, which leads to improved cycling performance of Li-metal batteries.

1. Z. Huang et al, A solvent-anchored non-flammable electrolyte, Matter, 2023 (highlighted by C&EN, Materials Today, Stanford Eng, etc)
2. Z Huang et al, Effects of Polymer Coating Mechanics at Solid-Electrolyte Interphase for Stabilizing Lithium Metal Anodes, Adv. Eng. Mat, 2022
3. Z Huang et al, A Cation-Tethered Flowable Polymeric Interface for Enabling Stable Deposition of Metallic Lithium, JACS, 2020
4. S Choudhury*, Z Huang*, C Amachuku*, P Rudnicki*, et al, Ion Conducting Polymer Interfaces for Lithium Metal Anodes: Impact on the Electrodeposition Kinetics, Adv. Eng. Mat, 2023
5. Z Huang et al, A salt-philic solvent-phobic interfacial coating design for lithium metal electrodes, Nat. Energy , 2023