Improving Effect of Graphene on Electrochemical Properties of Fe2O3 Anode Materials

Transition metal oxides have a high initial charge-discharge capacity of 800–1000 mAh/g, the electrochemical performance, cyclic performance and rate performance of the composite of transition metal oxide and graphene have been improved due to the unique two-dimensional structure and excellent electrical conductivity of graphene. In this paper, iron oxides materials with different morphs were prepared by different hydrothermal reaction temperatures, and rGO/Fe2O3-175 °C composites with different graphene ratios were synthesized and used in the anode of lithium ion batteries. The results show that nanorod-shaped Fe2O3 had better electrochemical performance than spherical Fe2O3. 0.2rGO/Fe2O3-175 °C had the best cyclic performance, the first cyclic discharge capacity reaches 1372 mAh/g under the current density of 100 mA/g, and the cyclic reversible capacity remained at about 435 mAh/g after 50 cycles, illustrating that nanorods Fe2O3 and graphene composites can greatly buffer the volume expansion of Fe2O3.

Integrated Design of Hierarchical CoSnO3@NC@MnO@NC Nanobox as Anode Material for Enhanced Lithium Storage Performance

Transition-metal oxides (TMOs) are potential candidates for anode materials of lithium-ion batteries (LIBs) due to their high theoretical capacity (∼1000 mA h/g) and enhanced safety from suppressing the formation of lithium dendrites. However, the poor electron conductivity and the large volume expansion during lithiation/delithiation processes are still the main hurdles for the practical usage of TMOs as anode materials. In this work, the CoSnO3@NC@MnO@NC hierarchical nanobox (CNMN) is then proposed and fabricated to solve those issues. The as-prepared nanobox contains hollow cubic CoSnO3 as a core and dual N-doped carbon-"sandwiched" MnO particles as a shell. As anode materials of LIBs, the hollow and carbon interlayer structures effectively accommodate the volume expansion while dual active TMOs of CoSnO3 and MnO efficiently increase the specific capacity. Notably, the dual-layer structure of N-doped carbons plays a critical functional role in the incorporated composites, where the inner layer serves as a reaction substrate and a spatial barrier and the outer layer offers electron conductivity, enabling more effective involvement of active anode materials in lithium storage, as well as maintaining their high activity during lithium cycling. Subsequently, the as-prepared CNMN exhibits a high specific capacity of 1195 mA h/g after the 200th cycle at 0.1C and an excellent stable reversible capacity of about 876 mA h/g after the 300th cycle at 0.5C with only 0.07 mA h/g fade per cycle after 300 cycles. Even after a 250 times fast charging/discharging cycle both at 5C, it still retains a reversible capacity of 422.6 mA h/g. We ascribe the enhanced lithium storage performances to the novel hierarchical architectures achieved from the rational design.

SnO2@C@VO2 Composite Hollow Nanospheres as an Anode Material for Lithium-Ion Batteries

Porous SnO₂@C@VO₂ composite hollow nanospheres were ingeniously constructed through the combination of layer-by-layer deposition and redox reaction. Moreover, to optimize the electrochemical properties, SnO₂@C@VO₂ composite hollow nanospheres with different contents of the external VO₂ were also studied. On the one hand, the elastic and conductive carbon as interlayer in the SnO₂@C@VO₂ composite can not only buffer the huge volume variation during repetitive cycling but also effectively improve electronic conductivity and enhance the utilizing rate of SnO₂ and VO₂ with high theoretical capacity. On the other hand, hollow nanostructures of the composite can be consolidated by the multilayered nanocomponents, resulting in outstanding cyclic stability. In virtue of the above synergetic contribution from individual components, SnO₂@C@VO₂ composite hollow nanospheres exhibit a large initial discharge capacity (1305.6 mAhg^-1) and outstanding cyclic stability (765.1 mAhg^-1 after 100 cycles). This design of composite hollow nanospheres may be extended to the synthesis of other nanomaterials for electrochemical energy storage.

S-Doped TiSe2 Nanoplates/Fe3 O4 Nanoparticles Heterostructure

2D Sulfur-doped TiSe₂ /Fe₃ O₄ (named as S-TiSe₂ /Fe₃ O₄ ) heterostructures are synthesized successfully based on a facile oil phase process. The Fe₃ O₄ nanoparticles, with an average size of 8 nm, grow uniformly on the surface of S-doped TiSe₂ (named as S-TiSe₂ ) nanoplates (300 nm in diameter and 15 nm in thickness). These heterostructures combine the advantages of both S-TiSe₂ with good electrical conductivity and Fe₃ O₄ with high theoretical Li storage capacity. As demonstrated potential applications for energy storage, the S-TiSe₂ /Fe₃ O₄ heterostructures possess high reversible capacities (707.4 mAh g^-1 at 0.1 A g^-1 during the 100th cycle), excellent cycling stability (432.3 mAh g^-1 after 200 cycles at 5 A g^-1 ), and good rate capability (e.g., 301.7 mAh g^-1 at 20 A g^-1 ) in lithium-ion batteries. As for sodium-ion batteries, the S-TiSe₂ /Fe₃ O₄ heterostructures also maintain reversible capacities of 402.3 mAh g^-1 at 0.1 A g^-1 after 100 cycles, and a high rate capacity of 203.3 mAh g^-1 at 4 A g^-1 .

A facile synthesis of Fe3O4 nanoparticles/graphene for high-performance lithium/sodium-ion batteries

Diamond-like Fe₃O₄ nanoparticle/graphene composites prepared by a facile and simple co-precipitation method exhibit outstanding electrochemical properties for LIBs/SIBs.

Synergistic lithium storage of a multi-component Co2SnO4/Co3O4/Al2O3/C composite from a single-source precursor

Co₂SnO₄/Co₃O₄/Al₂O₃/C composite is prepared from a laurate anion-intercalated CoAlSn-layered double hydroxide single-source precursor, and delivers highly enhanced electrochemical performances.