• 文献标题:   Directional Flow-Aided Sonochemistry Yields Graphene with Tunable Defects to Provide Fundamental Insight on Sodium Metal Plating Behavior
  • 文献类型:   Article
  • 作  者:   LIU W, LI PY, WANG WW, ZHU D, CHEN YG, PEN SL, PAEK E, MITLIN D
  • 作者关键词:   liquid phase exfoliation lpe, lithium metal battery lmb, carbon host, carbon template, carbon support, dendrite, additive, fluoroethyelene carbonate fec
  • 出版物名称:   ACS NANO
  • ISSN:   1936-0851 EI 1936-086X
  • 通讯作者地址:   Sichuan Univ
  • 被引频次:   7
  • DOI:   10.1021/acsnano.8b06051
  • 出版年:   2018

▎ 摘  要

We report a directional flow-aided sonochemistry exfoliation technique that allows for unparalleled control of graphene structural order and chemical uniformity. Depending on the orientation of the shockwave relative to the flow-aligned graphite flakes, the resultant bilayer and trilayer graphene is nearly defect free (at-edge sonication graphene "AES-G") or is highly defective (in-plane sonication graphene "IPS-G"). AES-G has a Raman G/D band intensity ratio of 14.3 and an XPS-derived O content of 1.3 at. %, while IPS-G has an I-G/D of 1.6 and 6.2 at. % O. AES-G and IPS-G are then employed to understand the role of carbon support structure and chemistry in Na metal plating/stripping for sodium metal battery anodes. The presence of graphene defects and oxygen groups is highly deleterious: In a standard carbonate solution (1 M NaClO4, 1:1 EC-DEC, 5 vol % FEC), AES-G gives stable cycling at 2 mA/cm(2) with 100% Coulombic efficiency (CE) (within instrument accuracy) and an area capacity of 1 mAh/cm(2). Meanwhile IPS-G performs on-par with the baseline Cu support in terms of poor CE, severe mossy metal dendrites, and periodic electrical shorts. We argue that solid electrolyte interface (SEI) stability is the key for stable cycling, with defects of IPS-G being catalytic toward SEI formation. For IPS-G, the SEI layer also shows F-rich "hot spots" due to accelerated decomposition of FEC additive in localized regions.