Graphene‐Encapsulated Nanosheet‐Assembled Zinc–Nickel–Cobalt Oxide Microspheres for Enhanced Lithium Storage

Abstract

The appropriate combination of hierarchical transition-metal oxide (TMO) micro-/nanostructures constructed from porous nanobuilding blocks with graphene sheets (GNS) in a core/shell geometry is highly desirable for high-performance lithium-ion batteries (LIBs). A facile and scalable process for the fabrication of 3D hierarchical porous zinc-nickel-cobalt oxide (ZNCO) microspheres constructed from porous ultrathin nanosheets encapsulated by GNS to form a core/shell geometry is reported for improved electrochemical performance of the TMOs as an anode in LIBs. By virtue of their intriguing structural features, the produced ZNCO/GNS core/shell hybrids exhibit an outstanding reversible capacity of 1015 mA h g(-1) at 0.1 C after 50 cycles. Even at a high rate of 1 C, a stable capacity as high as 420 mA h g(-1) could be maintained after 900 cycles, which suggested their great potential as efficient electrodes for high-performance LIBs.

Ultrathin Co–Fe hydroxide nanosheet arrays for improved oxygen evolution during water splitting

“…Peak tting analysis identied two Co states, with the characteristic peaks at binding energies of 797.4 and 781.5 eV identied as Co 2+ , while the other two peaks at 796.1 and 780.5 eV are assigned to Co 3+ . 39,40 Peak tting analysis of the Co 2p spectra for the other Co-Fe bimetal NSAs hydroxides produced similar results to those of the Co 0.70 Fe 0.30 (OH) x NSAs. Without Fe doping, the main peaks of Co 2p 3/2 and Co 2p 1/2 were at higher energy regions and only one chemical state of Co (Co 2+ at 782.2 and 797.8 eV) was detected.…”

Hierarchical Structures Based on Two‐Dimensional Nanomaterials for Rechargeable Lithium Batteries

“…This type of hierarchical structure is so far applicable to many TMOs/TMDs with various shapes, such as Fe 3 O 4 hollow sphere, [71] TiO 2 hollow tubular, [72] MoS 2 hollow tubular, [73] MoS 2 hollow box. Apart from the TMOs/TMDs, some hollow structured polynary TMOs/TMDs (e.g., CoMn 2 O 4 hollow sphere, [79] Graphene-encapsulated ZnNiCoO microsphere, [80] M-Mn based oxides hollow tubular, [81] core-shelled NiCo 2 O 4 hollow sphere, [82] multi-shelled NiCo 2 S 4 hollow sphere [83] ) were also attractive electrode materials for LIBs and Li-O 2 batteries and etc. It is worth reminding that the excess empty space greatly reduces tap density, resulting in low volumetric energy and power density of electrode fabricated from these single-shelled materials.…”

Dual Electrostatic Assembly of Graphene Encapsulated Nanosheet‐Assembled ZnO‐Mn‐C Hollow Microspheres as a Lithium Ion Battery Anode

“…Unfortunately, simply mixing between graphene and active materials results in poor interfacial interaction, which is bad for the improvement of lithium storage properties. Although the surface charge modification of oxide particles can enhance the interfacial interaction with graphene, the synthesis process is tedious and time‐consuming . Thereby, it is of great significance to develop a facile and effective approach toward the design and fabrication of graphene/oxide hybrid electrode materials with strong interfacial interaction, although great challenges still remain up to now.…”