Topotactic Conversion Route to Mesoporous Quasi‐Single‐Crystalline Co₃O₄ Nanobelts with Optimizable Electrochemical Performance

Abstract

The growth of mesoporous quasi‐single‐crystalline Co3O4 nanobelts by topotactic chemical transformation from α‐Co(OH)2 nanobelts is realized. During the topotactic transformation process, the primary α‐Co(OH)2 nanobelt frameworks can be preserved. The phases, crystal structures, morphologies, and growth behavior of both the precursory and resultant products are characterized by powder X‐ray diffraction (XRD), electron microscopy—scanning electron (SEM) and transmission electron (TEM) microscopy, and selected area electron diffraction (SAED). Detailed investigation of the formation mechanism of the porous Co3O4 nanobelts indicates topotactic nucleation and oriented growth of textured spinel Co3O4 nanowalls (nanoparticles) inside the nanobelts. Co3O4 nanocrystals prefer [0001] epitaxial growth direction of hexagonal α‐Co(OH)2 nanobelts due to the structural matching of [0001] α‐Co(OH)2//[111] Co3O4. The surface‐areas and pore sizes of the spinel Co3O4 products can be tuned through heat treatment of α‐Co(OH)2 precursors at different temperatures. The galvanostatic cycling measurement of the Co3O4 products indicates that their charge–discharge performance can be optimized. In the voltage range of 0.0–3.0 V versus Li+/Li at 40 mA g−1, reversible capacities of a sample consisting of mesoporous quasi‐single‐crystalline Co3O4 nanobelts can reach up to 1400 mA h g−1, much larger than the theoretical capacity of bulk Co3O4 (892 mA h g−1).

Porous Electrode Materials for Lithium‐Ion Batteries – How to Prepare Them and What Makes Them Special

“…[ 117 ] These nanobelts possess a layered hydrotalcite structure and are ca. 20-50 nm thick, 200-500 nm wide, and tens of μ m long.…”

Evaluating the performance of nanostructured materials as lithium-ion battery electrodes

“…The porosity of Co3O4 nanowire samples has been suggested to aid the structural integrity of the material by accommodating much of the volume strain associated with the early intercalation of Li + (LixCo2O3), and the phase changes brought about during the electrochemical conversion sequence [189]. Other reported 1D Co3O4 nanostructures of note include C/Co3O4 nanowires [191], CNT-templated porous nanotubes [192], solution-grown needle-like nanotubes [193], nanoneedles [194], and nanobelts [195]. In particular, mesoporous Co3O4 nanobelts, which were prepared by the calcination of α-Co(OH)2 nanobelts, delivered high capacity and stable early cycling.…”

“…The Co3O4 nanobelts delivered capacities of up to ~1900 mA h g -1 in the first cycle (at a current density of 40 mA g -1 ), and displayed a reversible capacity of ~1400 mA h g -1 after 20 cycles. Although the unique structuring enabled high capacity at relatively low rates, the nanobelts ultimately suffered from poor rate performance, with stable capacities only obtained at C-rate [195]. Other recent examples of Co3O4 nanostructures demonstrated include nanosheets [196], multi-shelled hollow spheres [197] and octahedral nanocages [198].…”

A facile method to improve the high rate capability of Co3O4 nanowire array electrodes

“…Co 3 O 4 has been demonstrated to be a promising electrode material for LIBs and pseudo-type SCs due to its low environmental footprint, low cost and extremely high theoretical specific capacitance (3560 F/g) for SCs and capacity (890 mA·h/g) for LIBs [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Furthermore, cobalt oxide directly grown on current collectors in the form of highly oriented nanowires (NWs) has several additional advantages for applications in electrodes [2].…”