Enhanced Lithium- and Sodium-Ion Storage in an Interconnected Carbon Network Comprising Electronegative Fluorine

Abstract

Fluorocarbon (CF) anode materials were developed for lithium- and sodium-ion batteries through a facile one-step carbonization of a single precursor, polyvinylidene fluoride (PVDF). Interconnected carbon network structures were produced with doped fluorine in high-temperature carbonization at 500-800 °C. The fluorocarbon anodes derived from the PVDF precursor showed higher reversible discharge capacities of 735 mAh g and 269 mAh g in lithium- and sodium-ion batteries, respectively, compared to the commercial graphitic carbon. After 100 charge/discharge cycles, the fluorocarbon showed retentions of 91.3% and 97.5% in lithium (at 1C) and sodium (at 200 mA g) intercalation systems, respectively. The effects of carbonization temperature on the electrochemical properties of alkali metal ion storage were thoroughly investigated and documented. The specific capacities in lithium- and sodium-ion batteries were dependent on the fluorine content, indicating that the highly electronegative fluorine facilitates the insertion/extraction of lithium and sodium ions in rechargeable batteries.

Hard Carbons for Sodium‐Ion Battery Anodes: Synthetic Strategies, Material Properties, and Storage Mechanisms

“…Conductivity enhancements, an increase in defectd ensity,areduction in the reactionand diffusion barriers, an increase in the interlayers eparations, anda ni ncreasei nt he nanovoid volume are some of the effects brought aboutb yd oping strategies to positivelyi nfluence the host carbonm aterial for SIB electrode storage. [51][52][53][54] Doping with certain groups,s uch as PO x ,i sn oted to lead to substantial enhancement in capacitive storaget hrough the sodiump ore-filling mechanism,a part from minor enhancements in intercalation capacities. [38] Doping of various heteroatoms, including N, S, B, Fa nd P, and their codoping in hard carbon systems has been widely studied in the context of their applicability as anode materials in SIBs.…”

“…[51,66,67] Qie et al investigated the effect of sulfur doping in the performance of hard carbon as an anode material for SIBs. [51,66,67] Qie et al investigated the effect of sulfur doping in the performance of hard carbon as an anode material for SIBs.…”

“…[38] Doping of various heteroatoms, including N, S, B, Fa nd P, and their codoping in hard carbon systems has been widely studied in the context of their applicability as anode materials in SIBs. [51][52][53][54] Doping with certain groups,s uch as PO x ,i sn oted to lead to substantial enhancement in capacitive storaget hrough the sodiump ore-filling mechanism,a part from minor enhancements in intercalation capacities. [55] Nitrogen-doped hard carbon systems have been welle xplored as anode materials for SIBs.…”

“…It also exhibited an excellent rate capacity of 154 mAh g À1 at 15 Ag À1 and cyclic stability with as table capacity of 201 mAh g À1 at 5Ag À1 after 7000 charge-discharge cycles.I n addition to N, doping of other heteroatoms, includingS ,P ,B , and F, has also been shown to affect the electrochemical Na storagep roperties of hard carbons in ap ositive way. [51,66,67] Qie et al investigated the effect of sulfur doping in the performance of hard carbon as an anode material for SIBs. [63] This low-surface-area (39 m 2 g À1 )c arbon with ah igh sulfur content (15.17 at %) displayeda ne nlarged interplanar spacing (3.86 ;F igure 16).…”

On the Effect of Silicon Substitution in Na3V2(PO4)3 on the Electrochemical Behavior as Cathode for Sodium‐Ion Batteries

“…Excellent reviews about the research on electrode materials demonstrate that their capacity to electrochemically react reversibly with sodium can be competitive for certain applications, mainly applications related to large stationary electricity storage facilities powered by intermittent renewable energy sources. [11][12][13][14][15] Concerning cathode materials, transition metal phosphates, bearing a NASICON structure, exhibit an open framework, which facilitates the reversible insertion of sodium ions. [16] Particularly, the nominal stoichiometry Na 3 V 2 (PO 4 ) 3 has attracted much attention due to the excellent performance exhibited in both half and full cells.…”