Hierarchical porous MnCo<sub>2</sub>O<sub>4</sub> yolk–shell microspheres from MOFs as secondary nanomaterials for high power lithium ion batteries

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Oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are important reactions of energy storage and conversion devices. Therefore, it is highly desirable to design efficient and dual electrocatalysts for replacing the traditional noble-metal-based catalysts. Herein, we have developed a high-efficiency and low-cost MnCo2O4-rGO nanocomposite derived from bimetal-organic frameworks. For OER, MnCo2O4-rGO showed an onset potential of 1.56 V (vs reversible hydrogen electrode (RHE)) and a current density of 14.16 mA/cm2 at 1.83 V, being better than both pure MnCo2O4 and Pt/C. For ORR, MnCo2O4-rGO exhibited a half-wave potential (E1/2) of 0.77 V (vs RHE), a current density of 3.33 mA/cm2 at 0.36 V, a high electron transfer number n (3.80), and long-term stability, being close to the performance of Pt/C. The high activity of MnCo2O4-rGO was attributed to the synergistic effect among rGO, manganese, and cobalt oxide. As a result, the resultant MnCo2O4-rGO has a great potential to be applied as a high-efficiency ORR and OER electrocatalyst.

Section: Resultsmentioning

confidence: 93%

Anchoring MnCo₂O₄ Nanorods from Bimetal-Organic Framework on rGO for High-Performance Oxygen Evolution and Reduction Reaction

Yang

Zhu²,

Guo³

et al. 2019

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“…It is not difficult to see that there is a semicircle in the high frequency region and the intermediate frequency region, which is due to the formation of an SEI after cycling. 55 The first semicircle in the high frequency region is represented by R e in the equivalent circuit, while the second semicircle in the intermediate frequency region is represented by R ct . The equivalent circuit model was composed of R e , SEI resistance ( R s ), R ct , Warburg impedance ( W 1 ), and constant phase element.…”

Section: Results and Discussionmentioning

confidence: 99%

A Low-Cost SiO_x/C@Graphite Composite Derived from Oat Husk as an Advanced Anode for High-Performance Lithium-Ion Batteries

Sun

et al. 2022

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Silicon monoxide (SiO x ), as a promising anode for the next-generation high-power lithium-ion batteries, has some advantages such as higher lithium storage capacity (∼2400 mAh g –1 ), suitable working potential, and smaller volume variations during cycling compared with pure silicon. However, its disadvantages such as its inherent low conductivity and high cost impede its extensive applications. Herein, we have developed a low-cost and high-capacity SiO x /C@graphite (SCG) composite derived from oat husks by a simple argon/hydrogen reduction method. For further practical application, we also investigated the electrochemical performances of SiO x mixed with different ratios of graphite. As an advanced anode for lithium-ion batteries, the SCG-1 composite exhibits an excellent electrochemical performance in terms of lithium storage capacity (809.5 mAh g –1 at 0.5 A g –1 even after the 250th cycle) and high rate capability (479.7 mAh g –1 at 1 A g –1 after the 200th cycle). This work may pave the way for developing a low-cost silicon-based anode derived from biomass with a large reversible capacity and long cycle life in lithium-ion batteries.

“…It can be found that the specific capacity of the SCG-1100 hybrid decays first in the first 30th cycle and then rises in the following cycles, which is very similar to previous reports. 4 , 6 The first decay is due to the volume expansion effect of silicon particles in the cycling process. The repetitive volume changes could fracture the SEI layers and result in a more extensive exposure of Si active sites during the lithiation process.…”

Section: Results and Discussionmentioning

confidence: 99%

A Low-Cost and High-Capacity SiO_x/C@graphite Hybrid as an Advanced Anode for High-Power Lithium-Ion Batteries

Niu

et al. 2020

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Silicon suboxide (SiO x ) is one of the most promising anodes for the next-generation high-power lithium-ion batteries because of its higher lithium storage capacity than current commercial graphite, relatively smaller volume variations than pure silicon, and appropriate working potential. However, the high cost, poor cycling stability, and rate capability hampered its industrial applications due to its complex production process, volume changes during Li + insertion/extraction, and low conductivity. Herein, a low-cost and high-capacity SiO x /C@graphite (SCG) hybrid was designed and synthesized by a facile one-pot carbonization/hydrogen reduction process of the rice husk and graphite. As an advanced anode for lithium-ion batteries, the SiO x /C@graphite hybrid delivers a high reversible capacity with significantly enhanced cycling stability (842 mAh g –1 after 300 cycles at 0.5 A g –1 ) and rate capability (562 mAh g –1 after 300 cycles at 1 A g –1 ). The great improvement in performances could be attributed to the positive synergistic effect of SiO x nanoparticles as lithium storage active materials, the in situ-formed carbon matrix network derived from biomass functioning as an efficient three-dimensional conductive network and spacer to improve the rate capability and buffer the volume changes, and graphite as a conductor to further improve the rate capabilities and cycling stability by increasing the conductivity. The low-cost and high-capacity SCG derived from rice husk synthesized by a facile, scalable synthetic method turns out to be a promising anode for the next-generation high-power lithium-ion batteries.