Synergistic Effect of Mesoporous Co₃O₄Nanowires Confined by N-Doped Graphene Aerogel for Enhanced Lithium Storage

Abstract

A one-step multipurpose strategy is developed to realize a sophisticated design that simultaneously integrates three desirable components of nitrogen dopant, 3D graphene, and 1D mesoporous metal oxide nanowires into one hybrid material. This facile synthetic strategy includes a one-step hydrothermal reaction followed by topotactic calcination. The utilization of urea as the starting reagent enables the precipitation of precursor nanowires and concurrent doping of nitrogen heteroatoms on graphene during hydrothermal reaction, while at the same time the graphene nanosheets are self-assembled to afford a 3D scaffold. Detailed characterizations on the final calcined product are conducted to confirm the phase purity, porosity, nitrogen composition, and morphology. The integration of two building blocks, i.e., flexible graphene nanosheets and Co3 O4 nanowires, enables various intertwining behaviors such as seaming, bridging, hooping, bundling, and sandwiching, of which synergistic effect substantially enhances electrical and electrochemical properties of the resultant hybrid. For lithium ion battery application of the hybrid, a remarkably high capacity more than 1200 mA h g(-1) (at 100 mA g(-1) ) is stabilized over 100 cycles with coulombic efficiency higher than 97%. Even during rapid discharge/charge processes (1000 mA g(-1) ), a reversible charge capacity of 812 mA h g(-1) is still retained after 230 cycles.

Core–Shell Nitrogen‐Doped Carbon Hollow Spheres/Co3O4 Nanosheets as Advanced Electrode for High‐Performance Supercapacitor

“…The typical peaks of Co, C, and O are shown in the Co 3 O 4 /NHCS survey spectrum (Figure S7, Supporting Information), while the N peak is not evident due to the coating of Co 3 O 4 nanosheets on the surface of NHCS. In the Co 2p high‐resolution XPS spectrum (Figure c), two major peaks at 780.6 and 796.1 eV correspond to the Co 2p 3/2 and Co 2p 1/2 spin–orbit peaks, respectively, with a spin energy separation of 15.5 eV; while a pair of shake‐up satellite peaks at 785.9 and 801.4 eV are characteristic of Co 3 O 4 phase . Besides, two pairs of fitting peaks are assigned to Co 3+ (779.8 and 795.2 eV) and Co 2+ (781.1 and 796.4 eV), respectively.…”

Electrochemical Characteristics of Cobaltosic Oxide in Organic Electrolyte According to Bode Plots: Double‐Layer Capacitance and Pseudocapacitance

“…[9] Compared with double layer capacitance, the charge density stored with pseudocapacitance is several times higher. Among all sources, the pseudocapacitive contribution in transition metal oxides was not only demonstrated to show differential capacity (dQ/dV) curves [10] but also proven to become increasingly important, [3][4][5][11][12][13][14][15] which resulted in reversible capacities exceeding the theoretical value for Co 3 O 4 , [16][17][18][19][20][21][22][23][24][25] Fe 2 O 3 , [26][27][28][29][30] RuO 2 [31] and so forth. There are 3 possible sources for the capacities (charge storage) of electrode materials.…”

Formation of a Surficial Bifunctional Nanolayer on Nb2O5 for Ultrastable Electrodes for Lithium‐Ion Battery

“…However, constant demands for highly stable, safe LIBs are present, where safety issues and stable cycling as well as rate capability of LIBs are required for rechargeable batteries in the near future . Recently, various metal oxide materials have been investigated for their use in electrodes for LIBs, but most of metal oxide materials, except few, suffer from severe volume expansion which leads to formation of an unstable solid electrolyte interphase (SEI) layer and loss of electrical contact. Compared with most of metal oxides that undergo a conversion reaction, several metal oxides undergo an intercalation reaction, which has minimal volume expansion upon lithiation.…”