Surfactant-Assisted Synthesis of Fe₂O₃ Nanoparticles and F-Doped Carbon Modification toward an Improved Fe₃O₄@CF_<i>x</i>/LiNi_0.5Mn_1.5O₄ Battery

다국어 초록 (Multilingual Abstract)

<P>A simple surfactant-assisted reflux method was used in this study for the synthesis of cocklebur-shaped Fe<SUB>2</SUB>O<SUB>3</SUB> nanoparticles (NPs). With this strategy, a series of nanostructured Fe<SUB>2</SUB>O<SUB>3</SUB> NPs with a size distribution ranging from 20 to 120 nm and a tunable surface area were readily controlled by varying reflux temperature and the type of surfactant. Surfactants such as cetyltrimethylammonium bromide (CTAB), polyvinylpyrrolidone (PVP), poly(ethylene glycol)-<I>block</I>-poly(propylene glycol)-<I>block</I>-poly(ethylene glycol) (F127) and sodium dodecyl benzenesulfonate (SDBS) were used to achieve large-scale synthesis of uniform Fe<SUB>2</SUB>O<SUB>3</SUB> NPs with a relatively low cost. A new composite of Fe<SUB>3</SUB>O<SUB>4</SUB>@CF<SUB><I>x</I></SUB> was prepared by coating the primary Fe<SUB>2</SUB>O<SUB>3</SUB> NPs with a layer of F-doped carbon (CF<SUB><I>x</I></SUB>) with a one-step carbonization process. The Fe<SUB>3</SUB>O<SUB>4</SUB>@CF<SUB><I>x</I></SUB> composite was utilized as the anode in a lithium ion battery and exhibited a high reversible capacity of 900 mAh g<SUP>–1</SUP> at a current density of 100 mA g<SUP>–1</SUP> over 100 cycles with 95% capacity retention. In addition, a new Fe<SUB>3</SUB>O<SUB>4</SUB>@CF<SUB><I>x</I></SUB>/LiNi<SUB>0.5</SUB>Mn<SUB>1.5</SUB>O<SUB>4</SUB> battery with a high energy density of 371 Wh kg<SUP>–1</SUP> (vs cathode) was successfully assembled, and more than 300 cycles were easily completed with 66.8% capacity retention at 100 mA g<SUP>–1</SUP>. Even cycled at the high temperature of 45 °C, this full cell also exhibited a relatively high capacity of 91.6 mAh g<SUP>–1</SUP> (vs cathode) at 100 mA g<SUP>–1</SUP> and retained 54.6% of its reversible capacity over 50 cycles. Introducing CF<SUB><I>x</I></SUB> chemicals to modify metal oxide anodes and/or any other cathode is of great interest for advanced energy storage and conversion devices.</P><P><B>Graphic Abstract</B>
<IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-17/am504144d/production/images/medium/am-2014-04144d_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am504144d'>ACS Electronic Supporting Info</A></P>