Artificial cathode solid electrolyte interphase to endow highly stable lithium storage of FeF2 nanocrystals

Abstract

Iron difluoride (FeF 2 ) is considered a highcapacity cathode material for lithium-ion batteries. However, its specific capacity and stability are limited by the poor electrochemical kinetics of conversion reactions. Herein, the conversion reaction is confined in a localized nanosized space by encapsulating FeF 2 nanoparticles in polymer gelatin. The FeF 2 nanocrystal-coated polyvinylidene fluoride-based layer (defined as FeF 2 @100%G-40%P) was synthesized by glucoseassisted in-situ gelatinization to construct an artificial cathode solid electrolyte interphase via a solvothermal process. Thanks to the improved kinetics of the localized conversion reaction, the obtained FeF 2 @100%G-40%P electrodes show good cyclic stability (313 mA h g −1 after 150 cycles at 100 mA g −1 , corresponding to a retention of 80%) and a high rate performance (186.6 mA h g −1 at 500 mA g −1 ).

Fe/Fe3C modification to effectively achieve high-performance Si–C anode materials

“…It is revealed that Fe/Fe 3 C–Si@CNFs and Si@CNFs have organic fluorine from Li x PO y F z and Li x PF y and metal fluorine from Li–F and Fe–F, indicating that a dense inorganic component of the SEI film contains metal fluorine. 32,54,55 Interestingly, it has been reported that metal fluorine can not only effectively prevent electron tunneling and accelerate the diffusion of Li + in the SEI film but can also prevent the electrode from collapsing during volume expansion/contraction. However, organic fluorine is more likely to produce HF, which can corrode silicon–carbon, affecting the stable long cycling of the LIBs.…”

Toward High Energy Density FeFx (x=2 and 3) Cathodes for Lithium‐Ion Batteries

“…Various novel methods have been attempted to stabilize the electrode‐electrolyte interface, such as adding functional additives to the electrolyte or special surface treatments of the electrode. For example, a PVDF‐based artificial CEI layer coated on FeF 2 nanocrystals (FeF 2 @G‐P) was prepared by a one‐step solvent‐thermal method [109] . Owing to the thermal stability and sufficient strength of PVDF, the FeF 2 @G‐P electrode effectively prevents the Fe dissolution and cracking of FeF 2 particles (Figure 7a).…”

“…For example, a PVDF-based artificial CEI layer coated on FeF 2 nanocrystals (FeF 2 @G-P) was prepared by a one-step solvent-thermal method. [109] Owing to the thermal stability and sufficient strength of PVDF, the FeF 2 @G-P electrode effectively prevents the Fe dissolution and cracking of FeF 2 particles (Figure 7a). As a result, the FeF 2 @G-P composite displayed a discharge capacity of 313 mAh g À 1 at 0.1 A g À 1 over 150 cycles.…”

Metal Fluoride Cathode Materials for Lithium Rechargeable Batteries: Focus on Iron Fluorides

“…The effects of different electrolyte components (salts, solvents, and additives) on the performance of MF-based LIBs/LMBs have been analyzed by resear chers. [85,[203][204][205][206] The CEI film formation due to the decomposition of electrolytes at the cathode is universal and can aid in Small Methods 2023, 7, 2201152 Figure 8. a) Schematic illustration and the cycling ability of LiF/Fe/Cu nanocrystals produced using PLD.…”

“…The effects of different electrolyte components (salts, solvents, and additives) on the performance of MF‐based LIBs/LMBs have been analyzed by researchers. [ 85,203–206 ] The CEI film formation due to the decomposition of electrolytes at the cathode is universal and can aid in stabilizing the electrode/electrolyte interfaces and preventing further reduction/oxidation of the electrolyte solvent. Hence, the selection and further development of appropriate lithium salts and organic solvents for improving performance are versatile strategies to stabilize CEI films.…”