Well‐Designed Hierarchical Co₃O₄ Architecture as a Long‐Life and Ultrahigh Rate Capacity Anode for Advanced Lithium‐Ion Batteries

Abstract

LIBs achieves more inspiration as well as revealing the mechanism behind.Among various transitional metal oxides (TMOs, TM = Ni, Fe, Mn, Co, etc.) [1,3,5,[12][13][14][15][16][17][18] used as anode materials for next-generation LIBs, tricobalt tetroxide (Co 3 O 4 ) has attracted special interest due to its high theoretical specific capacity of 890 mAh g −1 based on an eight-electron electrochemical reaction (Co 3 O 4 + 8Li + 8e − ↔ 4Li 2 O + 3Co). [17,18] The dischargecharge processes involve reversible formation and decomposition of Li 2 O accompanying a reaction of metal Co. Like other TMOs, however, lithium storage performance of Co 3 O 4 is also impeded by the poor conductivity and large volume expansion or contraction during lithiation-delithiation cycles. To address those problems, especially in recent years, considerable efforts have been devoted to synthesize numerous Co 3 O 4 nanostructures with designed textures and morphologies, which can not only shorten the transport/diffusion distances for the electrolyte ions as well as enlarge the surface area to improve more reactive sites but also inhibit the crack and pulverization of electrodes (Table 1). Several encouraging results should be worthwhile to pay attention to. For instance, Liang et al. prepared porous Co 3 O 4 nanoplates transformed from Co(OH) 2 nanoplates obtained by hydrothermal method, and as an anode material for LIBs it delivered a high discharge capacity of 1001 mAh g −1 at the 80th cycle without obvious capacity fade at a current density of 0.2 C (178 mA g −1 ). [29] Using graphene oxide (GO) as a sacrificial template, Li et al. fabricated porous Co 3 O 4 nanosheets for LIBs which showed high reversible capacity of 1380 mAh g −1 after 240 cycles at 500 mA g −1 with a coulombic efficiency over 99.1%. [47] Li et al. reported a novel shale-like nanostructure assembled with Co 3 O 4 layers, it delivered a high reversible capacity of 1045 mAh g −1 at 200 mA g −1 after 100 cycles with rate capability. [48] The fact that the layer structures of nanoplates and nanosheets exhibited amazing lithium storage abilities was mainly attributed to their 2D structures with porous nature, in which higher surface area and richer edge sites enable to provide more reactive sites for electrochemical reaction and more spaces for facilitating Li ions transport across the units of the whole anodes. However, all of the works did not completely embody the cycling performance In a simple strategy of mild heat-assistant precipitation followed by annealing in air, hierarchical Co 3 O 4 flower-like microspheres self-constructed by porous nanosheets are synthesized in bulk and tested as an anode material for advanced lithium-ion batteries (LIBs). Benefited from its high porosity and specific surface area as well as a necessary short activation, the as-prepared architecture shows an enhanced lithium storage performance of high capacity, long-life cycle, and ultrahigh rate capacity compared with the great majority of reported and commercial Co 3 O 4 materials. Especial...

Constructing RuCoOx/NC Nanosheets with Low Crystallinity within ZIF‐9 as Bifunctional Catalysts for Highly Efficient Overall Water Splitting

“…The peaks at 780.0 and 795.0 eV are assigned to 2p 3/2 and 2p 1/2 signals of Co 3+ , and the peaks located at 782.8 and 797.8 eV are assigned to 2p 3/2 and 2p 1/2 signals of Co 2+ . The relative strong intensity of satellite peak could indicate the existence of CoO species except Co 3 O 4 , because the intensity of satellite peak for Co 3 O 4 should be very weak [41–43] . By comparing the Co 2p spectra of CoO x /NC, the binding energy of Co 2p in RuCoO x /NC‐350 shifts to a higher value with ∼0.5 eV.…”

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

“…As another typical transition metal oxide anode material, CoO x has been extensively studied because of its easy fabrication and high theoretical specific capacity (CoO: 716 mAh g −1 , Co 3 O 4 : 890 mAh g −1 ) . This anode material also suffers from large volume change.…”

Two-dimensional nanosheets as building blocks to construct three-dimensional structures for lithium storage

“…Inspired by the graphene, various graphene analogies such as silicene, phosphorene, and MXenes are emerging and can be also employed as building blocks to construct 3D structures. In this regard, various 3D structures built from 2D graphene analogies such as MoS 2 , MoO 3 , Co 3 O 4 and Si nanoflowers have been fabricated via hydrothermal treatments [96,[123][124][125] . Such flower-like structures could not only exhibit the unique properties of the individual nanosheet, but also could prevent the severe aggregation and re-stacking of 2D nanohseets.…”

“…The flower-like Co 3 O 4 hierarchical structures ( Fig. 16 b) fabricated by precursor-self-template method displayed a high reversible capacity of 1103 mAh g −1 at 500 mA g −1 [125] . The flower-like MoS 2 architecture ( Fig.…”