Nanotube Li₂MoO₄: a novel and high-capacity material as a lithium-ion battery anode

Abstract

Carbon-coated Li2MoO4 hexagonal hollow nanotubes were fabricated via a facile sol-gel method involving the solution synthesis of Li2MoO4 with subsequent annealing under an inert atmosphere to decompose the organic carbon source. To the best of our knowledge, this is the first report on the synthesis of Li2MoO4 nanotubes. More significantly, we have found that Li2MoO4 can be used as an anode material for lithium-ion batteries (LIBs). When evaluated as an anode material, the carbon-coated Li2MoO4 hollow nanotubes show an excellent electrochemical performance with a high reversible capacity (∼550 mA h g(-1)) after 23 cycles, good rate capability and cycling stability. Meanwhile, carbon-free Li2MoO4 sample, fabricated via a solid state reaction, was also prepared for comparison. The Li storage mechanism has been investigated in-detail by advanced XPS, in situ XRD and HRTEM.

Synthesis of One Dimensional Li2MoO4 Nanostructures and Their Electrochemical Performance as Anode Materials for Lithium-ion Batteries

“…However, the surface carbon content determined from XPS (31.5%) is larger than the overall carbon content from TGA and elemental analyzer results (3.03%), combined with the result of XRD shown inFig.3b, we can infer that the carbon is coating on the surface of these nanotubes in an amorphous form. These amorphous carbon shows a carbon layer form confirmed by the TEM image(Fig.4e)which is similar to the previous reports on carbon coating [11,29]. The binding energy of 284.7 eV observed from the C1s matches well with the coated carbon (CC-like), and, the low-intensity peaks appeared at 286.1 eV and 289.1 eV are correspond to the presence of CO-like and COO-like carbons which could be ascribed to the interface interconnect between carbon layer and nanotubes also shown inFig.4eas following.…”

“…This is a common drawback for these high-capacity metal oxide anode materials caused by the great fading capacity between lithiation and delithiation, which can be attributed to the side reactions such as the formation of solid electrolyte interface (SEI) layer and the irreversible reaction during the first lithiation process. [29] After the first cycle, the electrode reaction shows a high reversibility as the third cycle can repeat well both the curve shape and the specific capacity of the second cycle for all of them. From the second cycle, both of their discharge-charge capacities slowly decrease along the cycle number, after 50 cycles, a charging capacity of 179.8 mAh g -1 (carbon-free powders), 330 mAh g -1 (carbon-free nanorods), 377.2 mAh g -1 (carbon-free nanotubes) and 550.8 mAh g -1 (carbon-coated nanotubes) were obtained shown in Fig.9b.…”

“…[29] However, no research about the formation process of the nanostructures are discussed. In fact, sol-gel method has been known as a technique which can be used to synthesize one-dimensional nanostructure.…”

Synthesis of Carbon-coated Nanoplate α-Na 2 MoO 4 and its Electrochemical Lithiation Process as Anode Material for Lithium-ion Batteries

“…Based on the above structural and TEM analysis, we can infer that the Li storage mechanism of this material is a conversion reaction process similar to Li 2 MoO 4 , Na 0.25 MoO 3 and CaMoO 4 [18,[23][24][25][26]. Nano-crystal Mo and Li 2 O (amorphous) shown in Fig.…”

“…Especially to improve the electronic conductivity, carbon coating on the surface of materials has been a general method, therefore, combination of these two approaches will be favorable for Mobased electrode materials. Recently, a novel carbon-coated nanotube Li 2 MoO 4 has been reported as an anode material for Li-ion batteries which presents an excellent electrochemical performance [18].…”