Designation of a Nano‐Fe₃O₄ Based Composite Electrode with Long Cycle Life for Lithium‐Ion Batteries

Abstract

In order to address the issue of large volume expansion and poor electrical conductivity of Fe 3 O 4 -based anodes for lithiumion batteries, carbon and SiO x /SiC heterojunction double-shell coated Fe 3 O 4 (Fe x Si y ) nanocomposites were synthesized by crosslinking, pyrolysis and decarbonization of sol particles. The particles were produced by the reaction of iron carbonyl with liquid polycarbosilane using pitch as isolator, which is a low cost and easy to scale up preparation method. It is found that the double-shell structure of the nanoparticles not only solves the problem of comminution of Fe 3 O 4 during cycling, but also ensures stable cycling and superior rate performance. The FeOSiC-30 anode delivers a high reversible capacity (1357.2 mAh g À 1 for 550 cycles at 1 A g À 1 and 1060.7 mAh g À 1 for 2500 cycles at 5 A g À 1 ). The excellent electrochemical performance can be contributed to the novel structure: 1) the uniform carbon layer can improve the electrical conductivity and ensure the formation of a stable SEI; 2) different active materials can relieve the stress caused by volume variation and also contribute additional capacity; 3) the small particle size can offer a strong kinetic of electrochemical reactions and lithium ion transfer. These results can strongly support the improvement of the capacity of Fe 3 O 4 -based anodes by the unique multi-function structural design, also providing new pathways for the design of other electrode materials.

Enhanced Energy Storage of Fe3O4 Nanoparticles Embedded in N‐Doped Graphene

“…These limitations are mainly attributed to the low electronic and ionic conductivity of iron oxides as well as to the volume expansion and contraction during charge/discharge processes, which lead to the pulverization of Fe 3 O 4 electrodes. [28] To avoid these issues, the use of Fe 3 O 4 nanoparticles and nanometer-scale Fe 3 O 4 -based structures in combination with conductive material substrates (mainly carbon-based) are almost mandatory to achieve exceptionally high capacity and high cyclability properties with iron oxidenegative electrodes. [21,23,25,29,30] One strategy is to use carbon coatings to encapsulate the active material and thus, improve the electrical conductivity, while preventing the aggregation effect.…”

“…However, the practical application of Fe 3 O 4 as a negative electrode for LIBs is still limited by its unsatisfactory cycling life and poor rate capability. These limitations are mainly attributed to the low electronic and ionic conductivity of iron oxides as well as to the volume expansion and contraction during charge/discharge processes, which lead to the pulverization of Fe 3 O 4 electrodes . To avoid these issues, the use of Fe 3 O 4 nanoparticles and nanometer‐scale Fe 3 O 4 ‐based structures in combination with conductive material substrates (mainly carbon‐based) are almost mandatory to achieve exceptionally high capacity and high cyclability properties with iron oxide‐negative electrodes .…”