Robust, Ultrasmooth Fluorinated Lithium Metal Interphase Feasible via Lithiophilic Graphene Quantum Dots for Dendrite‐Less Batteries

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 18; no. 19; pp. e2200919 - n/a
• Main Authors: Senthil, Chenrayan, Kim, Seung Gyu, Kim, Sun‐Sik, Hahm, Myung Gwan, Jung, Hyun Young
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01-05-2022
• Subjects: Anodes; Cycles; dendrites; Dendritic structure; Electrolytes; Electrolytic cells; Fluorination; Fluorine; Graphene; graphene quantum dots; Lithium; lithium‐metal anodes; lithium‐sulfur batteries; Nanotechnology; Quantum dots; Robustness; solid electrolyte interphases; Solid electrolytes; Synergistic effect; dendrites; lithium-sulfur batteries; graphene quantum dots; solid electrolyte interphases; lithium-metal anodes
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202200919

Dendrite growth and in‐homogeneous solid electrolyte interphase (SEI) buildup of Li metal anodes hinder the longtime discharge–charge cycling and safety in secondary metal batteries. Here, the authors report an in‐situ restructured artificial lithium/electrolyte SEI exposing an ultrasmooth and thin layer mediated through graphene quantum dots (GQDs). The reformed artificial interphase comprises a mixture of organic/inorganic‐rich compositions alike as mosaic interphase, albeit the synergistic effect mediated via hydroxylated GQDs involving redeposition‐borne lithium, and its accumulated salts, facilitate a homogeneous and ultrasmooth near fluorine‐rich interfacial environment ensuring a facile lithium‐ion (Li‐ion) diffusion and dendritic‐free nature. As a result, symmetrical graphene dots‐lithium cells enable a dendrite‐less operation up to 2000 h with good cycling stability and capacity retention at current densities 1 and 5 mA cm−2 compared to bare lithium. The well‐established fluorinated interface engenders a high reversible capacity and stable performance during the initial and long‐term cycles upon configuring in lithium‐sulfur (Li‐S) cells. Thus, the authors’ work illuminates the direction toward achieving dendritic‐free smooth and robust metal anodes through manipulating and restructuring the critical SEI chemical components.
Uncontrolled Li redeposition being detrimental to dendrite formation is precisely regulated via size‐ and site‐specific lithiophilic quantum graphene dots to realize a reformed solid electrolyte interphase bearing a robust and ultrasmooth nature, enabling the Li metal to withstand more than 4000 plating/stripping cycles. The negligible mass of quantum dots explicates a reformed interphase leveraging exceptional stability to Li anode without compromising the interfacial chemical components and energy density of Li‐metal batteries.