Superior Electrochemical Properties of Composite Microspheres Consisting of Hollow Fe₂O₃ Nanospheres and Graphitic Carbon

Abstract

Several micron-sized composite microspheres comprising hollow metal oxide nanospheres and in situ-formed graphitic carbon (GC) can be efficiently applied as anode materials for lithium-ion batteries. Herein, unique porous structured microspheres consisting of hollow Fe 2 O 3 nanospheres and GC layers are prepared by spray drying. Fe nanocrystals are formed by carbothermal reduction. They are responsible for the transformation of the dextrin-derived amorphous carbon (AC) into welldeveloped GC layers, while the excess amount of dextrin remains as AC.The key point is the selective elimination of the AC without burning, which is achieved by a low-rate airflow during the oxidation process. Finally, porous-and hierarchical-structured Fe 2 O 3 -GC composite microspheres are obtained via Kirkendall diffusion. Because of their superior structural stability and excellent electrical conductivity, the porousstructured Fe 2 O 3 -GC microspheres show excellent lithium-ion storage performances. The discharge capacity of Fe 2 O 3 -GC-350 for the 1000th cycle at 3 A g −1 is 760 mA h g −1 , and their capacity retention calculated from the second cycle is 92%.

Hollow α‐Fe2O3 Nanotubes Embedded in Graphene Aerogel as High‐Performance Anode Material for Lithium‐Ion Batteries

“…The multiplets in Figure d showing the high resolution spectrum for Fe 2p indicated two strong peaks located at binding energies of 713.0 eV for Fe 2p3/2 and 727.5 eV for Fe 2p1/2 accompanied by two satellite peaks on its higher binding‐energy side, which were characteristic peaks of Fe 2 O 3 . It was evident that the oxidation state of Fe in this product was only Fe 2 O 3 …”

Morphological and Electrochemical Properties of ZnMn2O4 Nanopowders and Their Aggregated Microspheres Prepared by Simple Spray Drying Process

“…However, the ZnMn 2 O 4 powders post-treated at high temperatures of 800 and 1000 • C showed relatively good cycling performance even at a high current density of 2.0 A g −1 . On the other hand, and non-aggregated state between the microspheres [33][34][35]. After 100 cycles, the discharge capacities of the ZnMn 2 O 4 powders post-treated at 400, 600, 800, 1000 • C, and ZnMn 2 O 4 800 • C_AM were 431, 447, 532, 400, and 687 mA h g −1 , respectively.…”

Amorphous Cobalt Selenite Nanoparticles Decorated on a Graphitic Carbon Hollow Shell for High-Rate and Ultralong Cycle Life Lithium-Ion Batteries

“…Amorphous TMC materials possess a disordered structure with regard to anisotropy and defects, which could accelerate ionic diffusion through more active diffusion sites. − Moreover, amorphous structured materials could possess significant structural stabilities during repeated cycling owing to their intrinsically isotropic nature, which could release stress via volume variation. ,, Therefore, amorphous TMCs have also been applied as effective anode materials for LIBs. The formation of nanocomposites of TMCs and carbon-related materials with high electrical conductivities is also known as an efficient strategy for improving the electrochemical properties of TMCs. , In particular, graphitic carbon converted from amorphous carbon covering TMC anode materials has played key roles in enhancing electrochemical performances of TMCs by enhancing the structural stability and electrical conductivities of powders. − Park et al synthesized multishell structured microspheres comprising graphitic carbon-coated Fe 3 O 4 hollow nanospheres . Amorphous carbon infiltrated via a pitch solution dropping method was transformed into graphitic carbon layers, resulting in excellent electrochemical kinetic properties.…”