A bubble-template approach for assembling Ni–Co oxide hollow microspheres with an enhanced electrochemical performance as an anode for lithium ion batteries

Abstract

Although significant advancements in the preparation of metal oxide hollow structures have been achieved, most synthesis routes have some complicated aspects such as requiring a hard-template, multistep procedures or other special reagents. This paper proposes a green and facile bubble-template approach to synthesize and organize Ni-Co hollow microspheres. The entire formation mechanism for the hollow spherical structures, including integration for nucleation, morphological tailoring and an Ostwald ripening process, has been elucidated based on time-dependent observations. The Ni-Co hollow microspheres revealed an excellent cycling stability (730 mA h g(-1) even after 140 cycles at 300 mA g(-1)) and good rate capability when evaluated as an anode material for lithium ion batteries (LIBs). The excellent electrochemical performance can be attributed to the rational design and organization of the hollow structures, which offer a large void space for accommodating volume changes, shorten the diffusion path for Li ions and electron transfer, as well as increase the contact area between the electrodes and electrolyte. Moreover, the synergistic effects of the nickel and cobalt ions with different lithiation potentials allowed the volume change to occur in a stepwise manner. The bubble-template strategy was convenient and very effective for constructing the hollow structures, and if well engineered, it could be extended to the synthesis of other advanced metal oxide anode materials for high energy storage devices and many other applications.

Nickel-Iron Alloy Nanoparticle Characteristics Pre- and Post-Reaction With Orange G

“…The Ni2p 3/2 and Ni2p 1/2 peaks are similar for NiFe alloy nanoparticles found in literature for the treatment of azo dyes [8]. The peaks at 861.3 eV and 879.6 eV are satellite peaks which indicate an electron correlation in the system [8], [52]. The larger concentrations of Ni starting at Ni2.5Fe10 ratio show an additional peak at 852.2 eV, which indicates the presence of Ni metal in the nanoparticles [53].…”

High entropy oxides for reversible energy storage

“…The CVs and differential capacity plots establish that the absence of Zn leads to a two-step oxidation process, rather than a single one as for all the other samples (Supplementary Figure 9 ). These two oxidation peaks, centered around 1.7 V and 2.2 V, resemble the formation of individual NiO and CoO 17 , 27 . This suggest that, in the case of TM-MEO(-Zn), the parent rock-salt structure is apparently not regained upon Li extraction, but instead separates into different phases.…”

“…Although some conversion materials have been reported to show high specific capacities and high degrees of reversibility, most of them are tediously modified, e.g., regarding morphology and structure or they are coated with additional functional materials to enhance their electrochemical performance 17 – 19 . Usually, the particle size in conversion materials has a considerable influence on the electrochemical properties, since large size particles usually lead to low capacity as well as low rate capability and reversibility.…”

“…Furthermore, it is able to fully recover and even increase the initial capacity after raising the current to 3 A g −1 for 5 cycles, so that after 100 cycles a specific capacity of 770 mAh g −1 is reached. Capacity increase over prolonged cycling is typical of conversion type materials and can be attributed to activation processes, occurring in electrodes with large particle sizes 14 , 17 . Figure 1c shows the cycling performance of the TM-HEO over 300 cycles at 200 mA g −1 with two initial formation cycles at 50 mA g −1 .…”

Ultra-stable Mn1-xNixCO3 nano/sub-microspheres positive electrodes for high-performance solid-state asymmetric supercapacitors

“…The morphology of the as-prepared Figure 3 and satellite peaks emerged for the Ni 2p region are owing to the presence of Ni 2+ state in the Mn 0.75 Ni 0.25 CO 3 samples 34,35 . The high resolution spectra of C 1 s was convolute into three binding energy peaks and shown in Figure 4c.…”