The Role of Metallic Fe and Carbon Matrix in Fe[sub 2]O[sub 3]/Fe/Carbon Nanocomposite for Lithium-Ion Batteries

Abstract

A comparative study is made on the cycle and rate performance of three Fe 2 O 3 -containing electrodes. The first electrode is made from a commercial nanosized ͑Ͻ100 nm͒ Fe 2 O 3 powder, whereas the second is made from a carbon-supported nanosized Fe 2 O 3 ͑Fe 2 O 3 /carbon composite͒. The third electrode is prepared by modifying the second, incorporating the metallic Fe into the Fe 2 O 3 particles ͑Fe 2 O 3 /Fe/carbon composite͒. Three electrodes show the following performance order in the cycle retention and rate capability: nanosized Fe 2 O 3 Ͻ Fe 2 O 3 /carbon composite Ͻ Fe 2 O 3 /Fe/carbon composite. The reverse order is, however, found on both the electrode volume change and the evolution of internal resistance. Thus, the best performance observed with the Fe 2 O 3 /Fe/carbon composite electrode has been ascribed to the presence of a carbon support and metallic Fe, both of which seem to play two important roles: the buffering action against the massive volume change in Fe 2 O 3 particles and providing an electronically conductive network within the swollen electrode layer. © 2010 The Electrochemical Society. ͓DOI: 10.1149/1.3298891͔ All rights reserved. One of the recent issues in lithium-ion batteries ͑LIBs͒ concerns a high energy density, particularly for the rapidly increasing market of sophisticated electronic devices. Transition-metal oxides ͑M x O y , where M is Co, Ni, Fe, etc.͒ have emerged as a potential negative electrode material for high energy density LIBs because they deliver a specific capacity 2-3 times larger than that of the currently used graphite ͑372 mAh g −1 ͒. 1-6 Such a high capacity results from a reduction of metal ions to their elemental state according to the general reaction MO + 2Li + + 2e = Li 2 O + M 0 . As a result of the reduction reaction, nanosized metal particles that are dispersed in the Li 2 O matrix are formed ͑this is called conversion reaction͒, but are restored back to the original oxides by delithiation. The number of electrons involved in this charge-discharge process ͑that is, capacity͒ is thus determined by the oxidation state of metallic components; for instance, six electrons for Fe 2 O 3 . Among the transitionmetal oxides, iron oxide ͑Fe 2 O 3

Thermal and Morphological Study of Epoxy Matrix with Chemical and Physical Hybrid of Nanoclay/Carbon Nanotube

“…1a-iii), in addition to the pristine support peaks. This diffraction peak was well matched with that for the metallic Fe, 29 indicating that, during the reduction process, Fe 2 O 3 particles reduced to the metallic state. The literature 13,23 also states that Fe 2 O 3 should convert to metallic Fe to serve as seeds for the growth of CNTs under CVD, which was consistent with the WAXS pattern observed in this work.…”

“…The other diffraction peaks in this sample had been indexed with Fe 2 O 3 . 29 This showed that, during the calcination process, Fe 3+ ions, which intercalated into the layers of montmorillonite by wet impregnation with the Fe (NO 3 ) 3 solution, changed to Fe 2 O 3 . 13 The reduced support gave the most intense diffraction peak at 44.7° (Fig.…”

Fe@Ag nanoparticles decorated reduced graphene oxide as ultrahigh capacity anode material for lithium-ion battery

“…It is generally known that smallsized nanoparticles deposited on carbon materials such as rGO provide high specific surface area and fast redox reactions, which can reduce the charge transfer resistance [47].…”

Fabricating Fe3O4/Fe/Biocarbon Fibers using Cellulose Nanocrystals for High-Rate Li-ion Battery Anode

“…5c shows that there are two types of lattice fringes with lattice spacing of 0.202 and 0.252nm, correspond to the (110) planes of the Fe and the (311) planes of the Fe 3 O 4 ,respectively. Recently, Fe-doped ion oxide materials have been explored by physical mixture or thermal reduction of ion oxide for lithium storage, which showed better cycle performance than pure ion oxide[31]. The inactive Fe functionalities can reduce the electrode swelling during lithium insertion/desertion process.…”

“…The inactive Fe functionalities can reduce the electrode swelling during lithium insertion/desertion process. In addition, considering the high electric conductivity of metallic Fe, the trace Fe in Fe 3 O 4 /Fe/MBCFs can also reduce the internal resistance and enhancing the rate capacity[31,32].…”