Mesoporous Graphitic Carbon‐Encapsulated Fe₂O₃ Nanocomposite as High‐Rate Anode Material for Sodium‐Ion Batteries

Abstract

A mesoporous graphitic carbon-encapsulated Fe O nanocomposite is synthesized as a superior anode material for sodium-ion batteries. A threefold strategy is adopted to achieve a high rate performance. First, the mesoporous structure with high specific surface area and large pore volume facilitates the transfer of electrolyte and accommodates the large volume change. Secondly, graphitic carbon encapsulation further improves the electronic conductivity of the nanocomposite. Finally, ultrafine Fe O nanocrystals effectively shorten the Na diffusion length. Consequently, this nanocomposite exhibits stable and fast Na storage, thus leading to excellent rate capability and cyclability. Pseudocapacitive behavior is found to dominate in the redox reactions, accounting for the outstanding rate and cycling performance. In addition, full cells, assembled with O3-Na [Cu Fe Mn ]O as cathodes, present good electrochemical performance.

One‐Pot Hydrothermal Synthesis of ZnS Nanospheres Anchored on 3D Conductive MWCNTs Networks as High‐Rate and Cold‐Resistant Anode Materials for Sodium‐Ion Batteries

“…The nitrogen adsorption/desorption isotherm and BJH pore‐size distribution curve of ZnS/MWCNTs composites are shown in Figure e and 3 f. All the samples exhibit a type‐IV curve with H2 hysteresis, indicating to the mesoporous structure . The specific surface area of ZnS/MWCNTs‐A, B, C are calculated to be 108.7, 114.9, and 160.1 m2 g −1 , respectively while that of pure ZnS is only 48.4 m 2 g −1 (Figure S6a), which is mainly due to the 3D network structure formed by the introduction of MWCNTs and form a large number of pore structures .…”

“…On the other hand, the 3D MWCNTs network structures enable efficient diffusion of Na + along the longitudinal direction of nanotubes and the large cavities formed by the MWCNTs backbone supply large contact areas with electrolyte to facilitate Na + diffusion . In addition, ZnS/MWCNTs‐B with better electronic conductivity and smaller crystalline size exhibits higher electrochemical activity than pure ZnS and thus has faster Na + diffusion kinetics . Accordingly, the synergistic effect between nano‐sized ZnS and MWCNTs improve the overall Na + diffusion coefficient of the electrode material.…”

High performance columnar-like Fe2O3@carbon composite anode via yolk@shell structural design

“…4 (d), it can be clearly observed, unsurprisingly, that as the scan rate increases, the diffusion contribution decreases while the capacitive contribution increases. This enhancement can be attributed to the shortened ion diffusion lengths and highly exposed active surface/interface as a result of the refinement of the Fe 2 O 3 cores after cycling, the improvement of electronic conductivity after porous C coating and unique yolk@shell structure that may offer more active surface sites, ample lithium ion diffusion pathways together with superior elec-trolyte accessibility, resulting in enhanced Li + diffusion kinetics and thus boosting the surface capacitive processes, especially at ultrahigh rates [54,56] .…”

Pseudocapacitive Graphene‐Wrapped Porous VO2 Microspheres for Ultrastable and Ultrahigh‐Rate Sodium‐Ion Storage

“…[16][17][18] Therefore, considerable efforts have been devoted to designing various carbon-based composites and hollow porous structure for improving the structural stability and electronic and ionic conductivity. [24][25][26][27] Indeed, other materials like the vanadium oxides are also promising anode materials because of their low cost, high theoretical capacity and the abundant supply of vanadium resource. [24][25][26][27] Indeed, other materials like the vanadium oxides are also promising anode materials because of their low cost, high theoretical capacity and the abundant supply of vanadium resource.…”

“…[19][20][21][22][23] Amongst, most works have focused on the oxides of Fe, Co and Ni and achieved good results. [24][25][26][27] Indeed, other materials like the vanadium oxides are also promising anode materials because of their low cost, high theoretical capacity and the abundant supply of vanadium resource. [28][29][30][31][32] Especially, the monoclinic VO 2 , which has a bilayer structure with large lattice spacing and high capacity has been widely investigated.…”