ZnO/CoO and ZnCo₂O₄ Hierarchical Bipyramid Nanoframes: Morphology Control, Formation Mechanism, and Their Lithium Storage Properties

Abstract

Mastery over the structure of nanoscale materials can effectively tailor and regulate their electrochemical properties, enabling improvement in both rate capability and cycling stability. We report the shape-controlled synthesis of novel mesoporous bicomponent-active ZnO/CoO hierarchical multilayered bipyramid nanoframes (HMBNFs). The as-synthesized micro/nanocrystals look like multilayered bipyramids and consist of a series of structural units with similar frames and uniform sheet branches. The use of an appropriate straight-chain monoalcohol was observed to be critical for the formation of HMBNFs. In addition, the structure of HMBNFs could be preserved only in a limited range of the precursor ratio. An extremely fast crystal growth process and an unusual transverse crystallization of the ZnCo-carbonate HMBNFs were newly discovered and proposed. By calcination of ZnCo-carbonate HMBNFs at the atmosphere of nitrogen and air, ZnO/CoO and ZnCo2O4 HMBNFs were obtained, respectively. Compared to the ZnCo2O4 HMBNFs, the ZnO/CoO HMBNFs with a uniform distribution of nanocrystal ZnO and CoO subunits exhibited enhanced electrochemical activity, including greater rate capability and longer cycling performance, when evaluated as an anode material for Li-ion batteries. The superior electrochemical performance of the ZnO/CoO HMBNFs is attributed to the unique nanostructure, bicomponent active synergy, and uniform distribution of ZnO and CoO phases at the nanoscale.

In‐Situ Synthesis of 3D Carbon Coated Zinc‐Cobalt Bimetallic Oxide Networks as Anode in Lithium‐Ion Batteries

“…Figure a shows the first five cyclic voltammograms (CV) curves of the ZnO‐CoO@C composites electrode at a scan rate of 0.1 mV s −1 between 0.01 and 3.0 V. In the first cathodic scan, an intensified peak at 0.84 V and a weak peak at 0.72 V correspond to the complete reduction of CoO to Co and the initial reduction of ZnO to Zn, as well as the formation of amorphous Li 2 O and solid electrolyte interphase (SEI) film. Peaks between 0 and 0.4 V are due to the alloying process of Li−Zn . Subsequently, the peaks at 1.12 V and 1.62 V in the first anodic scan mainly correspond to the oxidation of Co and Zn with the Li 2 O decomposition ,.…”

Hierarchy Design in Metal Oxides as Anodes for Advanced Lithium‐Ion Batteries

“…The alloying reaction has made these metal oxides promising anode materials because of their high theoretical specific capacities. For example, SnO 2 has a theoretical capacity of 780 mAh g −1 while this is 978 mAh g −1 for ZnO . However, the Li storage capability of these metal oxides is largely restricted by their huge volume expansion (≈240%) upon cycling, leading to the pulverization of these anodes .…”

Designed Formation of MnO2@NiO/NiMoO4 Nanowires@Nanosheets Hierarchical Structures with Enhanced Pseudocapacitive Properties

“…As expected, the construction-a nd potential-related investigation of such materials has been expanded, and ranges from optical and catalytic to electrochemical applications. [25][26][27][28][29][30][31][32][33][34][35] By using Although the preparation of hierarchical structures of transition-metal oxides( TMOs) has been intensively studied in recent years, it is still ag reat challenge to synthesize hierarchical multicomponent TMOs. Herein, we reportaversatile methodt of abricate three-component TMOs, namely MnO 2 @NiO/NiMoO 4 nanowires@nanosheets hierarchical porous composite structures (HPCSs).…”