Regulating the Solvation Structure of Nonflammable Electrolyte for Dendrite-Free Li-Metal Batteries

Ting Zhang; Yuejiao Li; Nan Chen; Ziyue Wen; Yanxin Shang; Yuanyuan Zhao; Mingxia Yan; Minrong Guan; Feng Wu; Renjie Chen

doi:10.1021/acsami.0c19075

Regulating the Solvation Structure of Nonflammable Electrolyte for Dendrite-Free Li-Metal Batteries

ACS Appl Mater Interfaces. 2021 Jan 13;13(1):681-687. doi: 10.1021/acsami.0c19075. Epub 2021 Jan 5.

Authors

Ting Zhang¹, Yuejiao Li^{1

2}, Nan Chen^{1

2}, Ziyue Wen¹, Yanxin Shang¹, Yuanyuan Zhao¹, Mingxia Yan¹, Minrong Guan¹, Feng Wu^{1

2}, Renjie Chen^{1

2}

Affiliations

¹ School of Material Science & Engineering, Beijing Institute of Technology, Beijing 100081, China.
² Collaborative Innovation Center of Electric Vehicles in Beijing, Beijing 100081, China.

PMID: 33398985
DOI: 10.1021/acsami.0c19075

Abstract

High-energy-density Li-metal batteries are of great significance in the energy storage field. However, the safety hazards caused by Li dendrite growth and flammable organic electrolytes significantly hinder the widespread application of Li-metal batteries. In this work, we report a highly safe electrolyte composed of 4 M lithium bis(fluorosulfonyl)imide (LiFSI) dissolved in the single solvent trimethyl phosphate (TMP). By regulating the solvation structure of the electrolyte, a combination of nonflammability and Li dendrite growth suppression was successfully realized. Both Raman spectroscopy and molecular dynamics simulations revealed improved dendrite-free Li anode originating from the unique solvation structure of the electrolyte. Symmetric Li/Li cells fabricated using this nonflammable electrolyte had a long cycle life of up to 1000 h at a current density of 0.5 mA cm^-2. Furthermore, the Li₄Ti₅O₁₂/TMP-4/Li full cells also exhibited excellent cycling performance with a high initial discharge capacity of 170.5 mAh g^-1 and a capacity retention of 92.7% after 200 cycles at 0.2 C. This work provides an effective approach for the design of safe electrolytes with favorable solvation structure toward the large-scale application of Li-metal batteries.

Keywords: Li-metal batteries; dendrite growth; nonflammable electrolyte; phosphate solvent; solvation structure.