A synthesis of graphene/Co3O4 thin films for lithium ion battery anodes by coelectrodeposition (original) (raw)
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Electrochimica Acta, 2012
Solvothermally reduced graphene oxide (STRG) that was synthesized using N-methyl-2-pyrrolidone (NMP) solvent was first employed as an conducting additive up to 15 wt% to commercial graphite anodic material. Due to numerous functional groups on the surface of the STRG, the reversible capacity decreased as the amount of STRG in the anode increased. To overcome this disadvantage, nanosized metal oxides such as CuO and Co 3 O 4 were supported on the STRG and a small amount of the composites was added to commercial graphite in order to enhance cyclic performance of the anode. A variety of characterization techniques showed that the composite additive significantly increased the reversible cyclic capacity by reducing the irreversible capacity of STRG and by providing more space for lithium ion intercalation.
Materials Letters, 2013
Co 3 O 4 nanowire, nanoparticle network, and Co 3 O 4 /graphite nanocomposite were synthesized via a hydrothermal route accompanied with a post-annealing step. The Co 3 O 4 nanowire was formed without adding graphite; after introducing graphite, the morphology of the Co 3 O 4 nanocomposite changed to a network through the partial overlapping of nanoparticles. The electrochemical properties of the samples were studied as anode materials in lithium-ion batteries. The Co 3 O 4 /graphite nanocomposite outperforms two different pure Co 3 O 4 samples by showing superior Li-battery performance with dramatically enhanced cyclic performance at a current density of 500 mA/g and excellent rate performance. Its reversible capacity remains as high as 551 mA h/g after 50th cycle.
Angewandte Chemie International Edition, 2010
Electrochemically active metals and metal oxides such as Sn, Si, SnO 2 , and Co 3 O 4 [4] have long been considered as anode materials for lithium ion batteries because of their high theoretical capacities. However, a large specific volume change commonly occurs in the host matrix of these metals and metal oxides during the cycling processes, thus leading to pulverization of the electrodes and rapid capacity decay. To circumvent these obstacles, carbonaceous materials with high electrical conductivity and fair ductility have been widely chosen as matrices for metals and metal oxides to improve their cycle performance. In particular, graphene, which is a monolayer of carbon atoms arranged in a honeycomb network, is becoming one of the most appealing matrices because of its unique properties such as superior electrical conductivity, excellent mechanical flexibility, large surface area (2630 m 2 g À1 ), [7] and high thermal and chemical stability. In this regard, Si/graphene, SnO 2 /graphene, TiO 2 /graphene, and Co 3 O 4 /graphene hybrids or composites, in which metals or metal oxides are distributed onto the surface of graphene or between the graphene layers, have been fabricated by restacking graphene sheets in the presence of guest nanoparticles or corresponding organometallic precursors. Compared to other carbon matrices such as graphite, carbon black, and carbon nanotubes, graphene sheets can more effectively buffer the strain from the volume change of metals or metal oxides during the charging-discharging processes and preserve the high electrical conductivity of the overall electrode. Nevertheless, the metal and metal oxide nanoparticles are still prone to strong aggregation during the cycle processes because of nonintimate contact between graphene layers and active nanoparticles. [7] This leads to a decrease in capacity of most metal or metal oxide/graphene composites by 20-50 % of their first reversible capacity after 30 cycles. One of the most promising strategies to tackle the aggregation problem of metal and metal oxides in lithium ion batteries is to confine them within individual carbon shells. [17] A key challenge in this strategy is the achievement of both high electrical conductivity and a low-weight fraction of thin carbon layers on the surface of metal or metal oxide nanoparticles.
A novel and green synthesis of mixed phase CoO@Co3O4@C anode material for lithium ion batteries
Ionics, 2018
CoO composite materials had attracted wide attention due to their potential application in lithium ion batteries (LIBs). We report a green and novel solution method for making pristine Co 3 O 4 and mixed phase CoO@Co 3 O 4 @C composite anode electrodes in LIBs. The anode materials characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD diffraction pattern reveals that composite anode contains as a major phase of CoO and small amounts of cubic Co 3 O 4 and Co metal peaks are found as impurity phases. The SEM micrographs showed that CoO, Co 3 O 4 , and Co phases are distributed in amorphous carbon network. The electrochemical behavior of anodes material is investigated by galvanostatic discharge/charge measurements and cyclic voltammetry. The composite anode shows a reversible specific capacity approaching 447 ± 5 mAh g −1 after 10 cycles at 100 and 107 ± 5 mAh g −1 after 50 cycles at 500 mA g −1 as well as improved cyclic stability and excellent rate capability. The enhancement of the electrochemical performance is attributed to the good electric contact between the particles, easier lithium ion diffusion, and suppression of volume change of anode.
A MnOx–graphitic carbon composite from CO2 for sustainable Li-ion battery anodes
Materials advances, 2022
The increasing concentration of CO 2 in the atmosphere is the leading cause of the greenhouse gas effect. Carbon capture and storage is an important topic to develop sustainable technologies. Molten salt CO 2 capture and electrochemical transformation represent a suitable process to produce various carbon products, such as carbon nanofibers, carbon nanotubes, graphite, and graphene. The employment of graphitic anode materials for Li-ion batteries coming from CO 2 capture is ideal for increasing battery sustainability. Moreover, the addition of transition metal oxides represents a suitable strategy for new negative electrodes because conversion reactions lead to high specific capacities. Among them, manganese has gained attention due to its multiple valence states and numerous possible crystalline structures. In the present work, a MnO x-graphitic carbon composite obtained by electrolysis of CO 2 via molten Li 2 CO 3 is characterized and used to prepare a negative electrode for LIBs with an environmentally sustainable aqueous process.
Mechanism of Co3O4/graphene catalytic activity in Li–O2 batteries using carbonate based electrolytes
Electrochimica Acta, 2013
We synthesized a hybrid graphene/Co 3 O 4 catalyst by a simple chemical reduction method, and demonstrated that a Li-O 2 cell with the hybrid catalyst delivers a highly reversible capacity. We examined the role of the catalyst in Li-O 2 batteries and through careful analyses of the reactions in the battery, we found that the reaction path fundamentally changes with the use of catalyst, and propose a mechanism of how the rechargeability is improved in Li-O 2 batteries.
Electrochimica Acta, 2014
A facile, rapid, and scalable method is developed for the fabrication of hierarchical CoFe 2 O 4 @graphene (CFO@GN) hybrid films on conductive substrates as a promising binder-free lithium-ion batteries anode. The obtained films show network morphologies, and almost all of the CFO nanoparticles are also homogeneously embedded into the layered graphene network. The resulting binder-free CFO@GN electrode with 35.85 wt.% graphene exhibits excellent lithium storage performance with a high specific reversible capacity of 866.67 mAh g-1 at a high current densities of 1000 mA g-1 , and high rate capability. In addition, the reversible capacity can retain as high as 860 mAh g-1 and has no obvious decay after 200 cycles. This work supplies a versatile strategy for fabrication of other metal oxide@graphene hybrid films as an efficient way to improve the lithium storage performance.
Graphitized carbon and graphene modified Fe2O3/Li4Ti5O12as anode material for lithium ion batteries
Surface and Interface Analysis, 2016
Graphitized carbon (GC) and graphene (GE) modified Fe 2 O 3 /Li 4 Ti 5 O 12 (LTO) composites have been synthesized via a solid-state reaction, respectively. The structure, morphology and electrochemical performance of the materials have also been characterized with X-ray diffraction (XRD), scanning electron microscope (SEM) with an energy dispersive spectroscopy (EDS) system, X-ray photoelectron spectrometer (XPS), Fourier transform infrared spectroscopy (FTIR) and electrochemical measurements. The discharge capacities of Fe 2 O 3 /LTO, GC/Fe 2 O 3 /LTO and GE/Fe 2 O 3 /LTO are 100.2 mAh g À1 , 207.5 mAh g À1 and 238.9 mAh g À1 after 100 cycles at the current density of 176 mA g À1. The cyclic stability and rate capability are in the order of GE/Fe 2 O 3 / LTO > GC/Fe 2 O 3 /LTO > Fe 2 O 3 /LTO because of the synergistic effect between GC (GE) and Fe 2 O 3 /LTO.