High-Performance Cathode Material of FeF3·0.33H2O Modified with Carbon Nanotubes and Graphene for Lithium-Ion Batteries

Abstract

The FeF3·0.33H2O cathode material can exhibit a high capacity and high energy density through transfer of multiple electrons in the conversion reaction and has attracted great attention from researchers. However, the low conductivity of FeF3·0.33H2O greatly restricts its application. Generally, carbon nanotubes (CNTs) and graphene can be used as conductive networks to improve the conductivities of active materials. In this work, the FeF3·0.33H2O cathode material was synthesized via a liquid-phase method, and the FeF3·0.33H2O/CNT + graphene nanocomposite was successfully fabricated by introduction of CNTs and graphene conductive networks. The electrochemical results illustrate that FeF3·0.33H2O/CNT + graphene nanocomposite delivers a high discharge capacity of 234.2 mAh g−1 in the voltage range of 1.8–4.5 V (vs. Li+/Li) at 0.1 C rate, exhibits a prominent cycling performance (193.1 mAh g−1 after 50 cycles at 0.2 C rate), and rate capability (140.4 mAh g−1 at 5 C rate). Therefore, the electronic conductivity and electrochemical performance of the FeF3·0.33H2O cathode material modified with CNTs and graphene composite conductive network can be effectively improved.

Design of cobalt‐iron complex sulfides grown on nickel foam modified by reduced graphene oxide as a highly effect bifunctional electrocatalyst for overall water splitting

“…In addition, the as‐prepared Ni 3 S 2 ‐CoMoS x /NF also showed excellent performance with the current density of 10 mA·cm −2 at only 1.52 V, as well as remained stability for 65 hours in the process of overall water splitting 39 . The aim for furtherly improving HER and OER performance of transition metal sulfides, transition metal heteroatom doping has been verified to be one kind of most effective means by improving the electrocatalytic activities due to the increasing transition metal active sites and the adjustment of electron structures 40 . electrochemical materials, for example graphite, graphene, graphene oxide, carbon black and carbon nanotubes, can be applied to collect charges effectively, which is aimed to improve the adhesion of transition metal sulfides with graphite carbon carriers 41 .…”

Improved Cycling Stability of LiCoO2 at 4.5 V via Surface Modification of Electrodes with Conductive Amorphous LLTO Thin Film

“…Lithium ion batteries (LIBs) have been urged for high energy density, high rate capability, and long cycling life, with increasing energy storage demands in portable electronics, electrical vehicles, and stationary power sources [1][2][3]. The most direct way to increase LIBs' energy density is to apply cathode materials with higher capacities and/or higher working voltages [4][5][6][7][8]. LIBs with LiCoO 2 (LCO) cathode has gained great commercial success in the past 3 decades, especially as the power source for portable electronics, benefiting from its high specific capacity, high redox potential, and long cycling life [9][10][11][12].…”

First Mixed-Metal Fluoride Pyrochlores Obtained by Topotactic Oxidation of Ammonium Fluorides under F2 Gas

“…Nevertheless, the large band gap of FeF 3 induces an insulating behavior and thus a poor electron conductivity. To overcome such a problem, several strategies have been considered by (i) mixing FeF 3 with conductive carbon compounds (CNT, graphene, OMC, ...), − (ii) reducing the particle size, and (iii) reducing the band gap of materials by either substituting F – ions with O 2– /OH – ions or vacancies , or doping FeF 3 with isovalent cations (Ti, Cr, Mn, Co). − Therefore, in order to control the particle size and the fluorination degree, to obtain new cation combinations and to stabilize the metastable polymorphs, numerous synthesis routes have been explored. Mechanochemical synthesis is technically simple and gives high yields; it was successfully applied to prepare nanostructured metal fluorides. , Metal fluorides with a high surface area are obtained in hydrofluoric acid (HF) solutions using solvothermal or sol–gel methods. − In addition, solvothermal syntheses assisted by microwave heating give metastable and novel metal fluoride phases. − Nevertheless, the presence of water during the synthesis often leads to hydrated phases and also to frequent F – /OH – substitution, which can be detrimental to catalytic or electrochemical properties.…”