Sodium Metal Anodes with Self‐Correction Function Based on Fluorine‐Superdoped CNTs/Cellulose Nanofibrils Composite Paper. (15th February 2022)

• Record Type: Journal Article
• Authors: Xiao, Jian; Xiao, Nan; Li, Kai; Zhang, Lipeng; Ma, Xiaoqing; Li, Yong; Leng, Changyu; Qiu, Jieshan
• Is Part Of: Advanced functional materials. Volume 32:Number 21(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-02-15
• Subjects: fluorine superdoping -- NaF -- periodic structures -- self‐correction function -- sodium metal anodes; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202111133
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Despite much efforts to stabilize sodium metal anodes for promoting their commercial applications, achieving a safe cycling process without intrinsic dendrite growth remains difficult owing to the unstable reaction interface and irregular sodium metal propagation. Herein, fluorine‐superdoped carbon nanotubes with a fluorine content of 14.38 at% are achieved using a new oxidation‐assisted plasma strategy, and then alternately assembled with cellulose nanofibrils to form periodical conductive/dielectric composite paper with outstanding mechanical properties. The superdoping of fluorine facilitates the construction of a NaF‐dominated solid electrolyte interphase layer, while the periodical conductive/dielectric network re‐homogenizes electric field distribution around irregular sodium protrusions, realizing a "bottom‐up" sodium orientation deposition and the "self‐correction" functionality during sodium plating/stripping process. Density functional theory calculations reveal that the specific oxygen species (CO/CO) and fluorine species (semi‐ionic CF/covalent CF2 ) on the surface of carbon matrix, could remarkably trap active fluorine fragments and generate NaF with sodium metal, respectively, which promotes the superdoping of fluorine and forms dendrite‐free sodium anodes. This delicate structure renders the sodium anodes a low nucleation overpotential of ≈7 mV, high Coulombic efficiency of 99.5% over 300 cycles at 3 mA cm −2, stable operation for up to 2100 h under ≈16 mV, and excellent full battery performance. Abstract : A novel oxidation‐assisted fluorination method to realize fluorine superdoping of CNTs (14.38 at%) is demonstrated first, and a periodical conductive/dielectric composite paper is also developed via an alternating assembly strategy. Benefiting from the sufficient fluorine configurations and periodical electric field distribution, the NaF‐enriched reaction interface and self‐correction function of sodium dendrites are explored and decoupled by experimental and theoretical analysis.