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Electrochemical performance of NixCo1-xMoO4 (0 ≤ x ≤ 1) nanowire anodes for lithium-ion batteries.

Park KS, Seo SD, Shim HW, Kim DW - Nanoscale Res Lett (2012)

Bottom Line: NixCo1-xMoO4 (0 ≤ x ≤ 1) nanowire electrodes for lithium-ion rechargeable batteries have been synthesized via a hydrothermal method, followed by thermal post-annealing at 500°C for 2 h.The reversible capacity of NiMoO4 and Ni0.75Co0.25MoO4 nanowire electrodes was larger (≈520 mA h/g after 20 cycles at a rate of 196 mA/g) than that of the other nanowires.This enhanced electrochemical performance of NixCo1-xMoO4 nanowires with high Ni content was ascribed to their larger surface area and efficient electron transport path facilitated by their one-dimensional nanostructure.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Materials Science and Engineering, Ajou University, Suwon, 443-749, Republic of Korea. dwkim@ajou.ac.kr.

ABSTRACT
NixCo1-xMoO4 (0 ≤ x ≤ 1) nanowire electrodes for lithium-ion rechargeable batteries have been synthesized via a hydrothermal method, followed by thermal post-annealing at 500°C for 2 h. The chemical composition of the nanowires was varied, and their morphological features and crystalline structures were characterized using field-emission scanning electron microscopy and X-ray powder diffraction. The reversible capacity of NiMoO4 and Ni0.75Co0.25MoO4 nanowire electrodes was larger (≈520 mA h/g after 20 cycles at a rate of 196 mA/g) than that of the other nanowires. This enhanced electrochemical performance of NixCo1-xMoO4 nanowires with high Ni content was ascribed to their larger surface area and efficient electron transport path facilitated by their one-dimensional nanostructure.

No MeSH data available.


Related in: MedlinePlus

Electrochemical properties of NixCo1-xMoO4 nanowire electrodes. Variation of the discharge (open circles)-charge (solid circles) specific capacity and coulombic efficiency (solid triangle) versus the cycle number at a rate of C/5 for the NixCo1-xMoO4 nanowire electrodes with various x values (by KS Park et al.).
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Figure 5: Electrochemical properties of NixCo1-xMoO4 nanowire electrodes. Variation of the discharge (open circles)-charge (solid circles) specific capacity and coulombic efficiency (solid triangle) versus the cycle number at a rate of C/5 for the NixCo1-xMoO4 nanowire electrodes with various x values (by KS Park et al.).

Mentions: Figure 5 shows the specific capacity of NixCo1-xMoO4 nanowire electrodes versus the cycle number at a current rate of C/5. When the values of x were 0, 0.25, and 0.5, the reversible capacities of NixCo1-xMoO4 nanowire electrodes faded rapidly even during the initial cycles, resulting in a poor reversible capacity of ≈290 mA h/g after 20 cycles. This result was attributed to the small surface areas of the nanowire electrodes. From the BET results summarized in Table 1 it was found that their surface areas were very small compared with those of the other nanowires, which led to a small electrode/electrolyte interface, resulting in a poor reversible capacity. Meanwhile, the reversible capacity of the NixCo1-xMoO4 nanowire electrodes with x values of 0.75 and 1 (≈520 mA h/g after 20 cycles) was larger than that of the previously mentioned three nanowire electrodes because of the increased electrode/electrolyte interface that resulted from the larger surface area of the nanowires (Table 1). In accordance with the BET results, the electrochemical performance of the NiMoO4 nanowire electrode was expected to be vastly superior compared with that of the Ni0.75Co0.25MoO4 nanowire electrode. However, the electrochemical performances of both electrodes were similar, as shown in Figure 5 due to the aggregation of the NiMoO4 nanowires. When we fabricated the positive electrode, the carbon black that is commonly used as a conducting additive was mechanically mixed with the nanowires as the active material. At that time, clusters formed by aggregation of the NiMoO4 nanowires could not be mixed efficiently with carbon black, which resulted in impairing their electrochemical performance by restriction of the electronic conduction paths from each nanowire to a current collector. In contrast, the Ni0.75Co0.25MoO4 nanowires did not form such clusters during the synthesis process. For this reason, the Ni0.75Co0.25MoO4 nanowire electrode could deliver a reversible capacity as high as the NiMoO4 nanowire electrode. Furthermore, the Ni0.75Co0.25MoO4 nanowire electrode exhibited a superior coulombic efficiency of ≈95% (Figure 5).


Electrochemical performance of NixCo1-xMoO4 (0 ≤ x ≤ 1) nanowire anodes for lithium-ion batteries.

Park KS, Seo SD, Shim HW, Kim DW - Nanoscale Res Lett (2012)

Electrochemical properties of NixCo1-xMoO4 nanowire electrodes. Variation of the discharge (open circles)-charge (solid circles) specific capacity and coulombic efficiency (solid triangle) versus the cycle number at a rate of C/5 for the NixCo1-xMoO4 nanowire electrodes with various x values (by KS Park et al.).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3278371&req=5

Figure 5: Electrochemical properties of NixCo1-xMoO4 nanowire electrodes. Variation of the discharge (open circles)-charge (solid circles) specific capacity and coulombic efficiency (solid triangle) versus the cycle number at a rate of C/5 for the NixCo1-xMoO4 nanowire electrodes with various x values (by KS Park et al.).
Mentions: Figure 5 shows the specific capacity of NixCo1-xMoO4 nanowire electrodes versus the cycle number at a current rate of C/5. When the values of x were 0, 0.25, and 0.5, the reversible capacities of NixCo1-xMoO4 nanowire electrodes faded rapidly even during the initial cycles, resulting in a poor reversible capacity of ≈290 mA h/g after 20 cycles. This result was attributed to the small surface areas of the nanowire electrodes. From the BET results summarized in Table 1 it was found that their surface areas were very small compared with those of the other nanowires, which led to a small electrode/electrolyte interface, resulting in a poor reversible capacity. Meanwhile, the reversible capacity of the NixCo1-xMoO4 nanowire electrodes with x values of 0.75 and 1 (≈520 mA h/g after 20 cycles) was larger than that of the previously mentioned three nanowire electrodes because of the increased electrode/electrolyte interface that resulted from the larger surface area of the nanowires (Table 1). In accordance with the BET results, the electrochemical performance of the NiMoO4 nanowire electrode was expected to be vastly superior compared with that of the Ni0.75Co0.25MoO4 nanowire electrode. However, the electrochemical performances of both electrodes were similar, as shown in Figure 5 due to the aggregation of the NiMoO4 nanowires. When we fabricated the positive electrode, the carbon black that is commonly used as a conducting additive was mechanically mixed with the nanowires as the active material. At that time, clusters formed by aggregation of the NiMoO4 nanowires could not be mixed efficiently with carbon black, which resulted in impairing their electrochemical performance by restriction of the electronic conduction paths from each nanowire to a current collector. In contrast, the Ni0.75Co0.25MoO4 nanowires did not form such clusters during the synthesis process. For this reason, the Ni0.75Co0.25MoO4 nanowire electrode could deliver a reversible capacity as high as the NiMoO4 nanowire electrode. Furthermore, the Ni0.75Co0.25MoO4 nanowire electrode exhibited a superior coulombic efficiency of ≈95% (Figure 5).

Bottom Line: NixCo1-xMoO4 (0 ≤ x ≤ 1) nanowire electrodes for lithium-ion rechargeable batteries have been synthesized via a hydrothermal method, followed by thermal post-annealing at 500°C for 2 h.The reversible capacity of NiMoO4 and Ni0.75Co0.25MoO4 nanowire electrodes was larger (≈520 mA h/g after 20 cycles at a rate of 196 mA/g) than that of the other nanowires.This enhanced electrochemical performance of NixCo1-xMoO4 nanowires with high Ni content was ascribed to their larger surface area and efficient electron transport path facilitated by their one-dimensional nanostructure.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Materials Science and Engineering, Ajou University, Suwon, 443-749, Republic of Korea. dwkim@ajou.ac.kr.

ABSTRACT
NixCo1-xMoO4 (0 ≤ x ≤ 1) nanowire electrodes for lithium-ion rechargeable batteries have been synthesized via a hydrothermal method, followed by thermal post-annealing at 500°C for 2 h. The chemical composition of the nanowires was varied, and their morphological features and crystalline structures were characterized using field-emission scanning electron microscopy and X-ray powder diffraction. The reversible capacity of NiMoO4 and Ni0.75Co0.25MoO4 nanowire electrodes was larger (≈520 mA h/g after 20 cycles at a rate of 196 mA/g) than that of the other nanowires. This enhanced electrochemical performance of NixCo1-xMoO4 nanowires with high Ni content was ascribed to their larger surface area and efficient electron transport path facilitated by their one-dimensional nanostructure.

No MeSH data available.


Related in: MedlinePlus