Ultrahigh coulombic efficiency electrolyte enables Li||SPAN batteries with superior cycling performance. (January 2021)

• Record Type: Journal Article
• Authors: Liu, Haodong; Holoubek, John; Zhou, Hongyao; Chen, Amanda; Chang, Naijen; Wu, Zhaohui; Yu, Sicen; Yan, Qizhang; Xing, Xing; Li, Yejing; Pascal, Tod A.; Liu, Ping
• Is Part Of: Materials today. Volume 42(2021)
• Page Start: 17
• Page End: 28
• Publication Date: 2021-01
• Subjects: Materials science -- Periodicals; Metallurgy -- Periodicals; Metal-work -- Periodicals; Biomedical and Dental Materials -- Periodicals; Manufactured Materials -- Periodicals; Metals -- Periodicals; 620.11
• DOI: 10.1016/j.mattod.2020.09.035
• Languages: English
• ISSNs: 1369-7021

Abstract

Graphical abstract: This novel electrolyte stabilizes both lithium metal anode and SPAN cathode for high energy density batteries with low cost. Abstract: Raising the coulombic efficiency of lithium metal anode cycling is the deciding step in realizing long-life rechargeable lithium batteries. Here, we designed a highly concentrated salt/ether electrolyte diluted in a fluorinated ether: 1.8 M LiFSI in DEE/BTFE (diethyl ether/bis(2, 2, 2-trifluoroethyl)ether), which realized an average coulombic efficiency of 99.37% at 0.5 mA cm −2 and 1 mAh cm −2 for more than 900 cycles. This electrolyte also maintained a record coulombic efficiency of 98.7% at 10 mA cm −2, indicative of its ability to provide fast-charging with high cathode loadings. Morphological studies reveal dense, dendrite free Li depositions after prolonged cycling, while surface analyses confirmed the formation of a robust LiF-rich SEI layer on the cycled Li surface. Moreover, we discovered that this ether-based electrolyte is highly compatible with the low-cost, high-capacity SPAN (Sulfurized polyacrylonitrile) cathode, where the constructed Li||SPAN cell exhibited reversible cathode capacity of 579 mAh g −1 and no capacity decay after 1200 cycles. A cell where a high areal loading SPAN electrode (>3.5 mAh cm −2 ) is paired with only onefold excess Li was constructed and cycled at 1.75 mA cm −2, maintaining a coulombic efficiency of 99.30% for the lithium metal. Computational simulations revealed that at saturation, the Li-FSI complex forms contact ion pairs, with a first solvation shell comprising DEE molecules, and a second solvation shell with a mix of DEE/BTFE. This study provides a path to enable high energy density Li||SPAN batteries with stable cycling.