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Self-assembly formation of hollow Ni-Fe-O nanocage architectures by metal-organic frameworks with high-performance lithium storage.

Guo H, Li T, Chen W, Liu L, Qiao J, Zhang J - Sci Rep (2015)

Bottom Line: The stable cyclic performance is obtained for all rates from 1 C to 10 C.Even when the current reaches 10 C, the capacity can also arrive at 652 mAhg(-1).Subsequently, a specific capacity of ca. 975 mAhg(-1) is recovered when the current rate reduces back to 1 C after 200 cycles.

View Article: PubMed Central - PubMed

Affiliation: School of Chemistry Science and Engineering, Yunnan University, Kunming 650091,Yunnan, China.

ABSTRACT
A hollow hybrid Ni-Fe-O nanomaterial (NiFe2O4) is synthesized using a precursor of metal-organic frameworks through a simple and cost-effective method. The unique hollow nanocage structures shorten the length of Li-ion diffusion. The hollow structure offers a sufficient void space, which sufficiently alleviates the mechanical stress caused by volume change. Besides, the hybrid elements allow the volume change to take place in a stepwise manner during electrochemical cycle. And thus, the hierarchical hollow NiFe2O4 nanocage electrode exhibits extraordinary electrochemical performance. The stable cyclic performance is obtained for all rates from 1 C to 10 C. Even when the current reaches 10 C, the capacity can also arrive at 652 mAhg(-1). Subsequently, a specific capacity of ca. 975 mAhg(-1) is recovered when the current rate reduces back to 1 C after 200 cycles. This strategy that derived from NMOFs may shed light on a new route for large-scale synthesis of hollow porous hybrid nanocages for energy storage, environmental remediation and other novel applications.

No MeSH data available.


TEM image of hollow structured NiFe2O4 nanocage electrodes after 200 cycles at 1C.
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f8: TEM image of hollow structured NiFe2O4 nanocage electrodes after 200 cycles at 1C.

Mentions: Similar to the simple oxide Fe2O3 and NiO, the mixed oxide NiFe2O4 stores Li through reversible formation and decomposition of Li2O. In the second scan, the reduction peaks are shifted to 0.94 and 1.56 V, respectively. The asymmetric nature of the plots suggests that the conversion reactions are only partially reversible and complete structural recovery to NiFe2O4 cannot occur32. As shown in Fig. 7c, the 1st discharge (Li+ insertion) and charge (Li+ extraction) curve at a current density of 1 C in the voltage window of 0.01–3 V (Fig. 7c) shows a wide, steady discharging plateau at ca. 0.65 V, followed by a gradual voltage decrease. The initial discharge and charge capacities are 1245 mAhg−1 and 1152 mAhg−1, respectively. The initial capacity loss should be attributed to the formation of solid electrolyte interphase (SEI) and the reduction of metal oxide to metal with Li2O formation. These results are consistent with CV analysis. From the second cycle onwards, the long potential plateau is replaced by a long slope between 1.2 and 0.73 V. After 200 cycles, the capacity can also be kept at 1071 mAhg−1, showing the excellent reversibility of electrode. To further investigate electrochemical performance, Fig. 7d shows the discharge capacities of NiFe2O4 electrode at different charging rates from 1 C to 10 C with 40 cycles. It can be seen that the stable cyclic performance can be obtained at all rates. Even when the current reaches 10 C, the capacity can also maintain at 652 mAh g−1. Subsequently, a specific capacity of ca. 975 mAhg−1 is recovered when the current rate reduces back to 1 C after 200 cycles. The overall rate performance demonstrates the high capacities in both low and high current rates of the prepared NiFe2O4 nanocage electrode. In Fig. 8, the TEM of NiFe2O4 electrode after 200 cycles at a current rate of 1 C reveals that the structure of this anode material can be retained well without breakage in the process of charge-discharge. Compared with the previously reported TMOs materials2433343536, the synthesized NiFe2O4 material in this work exhibits an enhanced electrochemical performance with our novel strategy. The unique hollow nanocage structures can shorten the length of Li-ion diffusion, which is beneficial to the rate performance. Furthermore, the hollow structure can offer a sufficient void space, sufficiently alleviating the mechanical stress caused by the volume change. Besides, the hybrid elements allow the volume change to take place in a stepwise manner during electrochemical cycle. As a result, the hierarchical hollow NiFe2O4 nanocage electrode can exhibit an extraordinary high electrochemical performance.


Self-assembly formation of hollow Ni-Fe-O nanocage architectures by metal-organic frameworks with high-performance lithium storage.

Guo H, Li T, Chen W, Liu L, Qiao J, Zhang J - Sci Rep (2015)

TEM image of hollow structured NiFe2O4 nanocage electrodes after 200 cycles at 1C.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4562299&req=5

f8: TEM image of hollow structured NiFe2O4 nanocage electrodes after 200 cycles at 1C.
Mentions: Similar to the simple oxide Fe2O3 and NiO, the mixed oxide NiFe2O4 stores Li through reversible formation and decomposition of Li2O. In the second scan, the reduction peaks are shifted to 0.94 and 1.56 V, respectively. The asymmetric nature of the plots suggests that the conversion reactions are only partially reversible and complete structural recovery to NiFe2O4 cannot occur32. As shown in Fig. 7c, the 1st discharge (Li+ insertion) and charge (Li+ extraction) curve at a current density of 1 C in the voltage window of 0.01–3 V (Fig. 7c) shows a wide, steady discharging plateau at ca. 0.65 V, followed by a gradual voltage decrease. The initial discharge and charge capacities are 1245 mAhg−1 and 1152 mAhg−1, respectively. The initial capacity loss should be attributed to the formation of solid electrolyte interphase (SEI) and the reduction of metal oxide to metal with Li2O formation. These results are consistent with CV analysis. From the second cycle onwards, the long potential plateau is replaced by a long slope between 1.2 and 0.73 V. After 200 cycles, the capacity can also be kept at 1071 mAhg−1, showing the excellent reversibility of electrode. To further investigate electrochemical performance, Fig. 7d shows the discharge capacities of NiFe2O4 electrode at different charging rates from 1 C to 10 C with 40 cycles. It can be seen that the stable cyclic performance can be obtained at all rates. Even when the current reaches 10 C, the capacity can also maintain at 652 mAh g−1. Subsequently, a specific capacity of ca. 975 mAhg−1 is recovered when the current rate reduces back to 1 C after 200 cycles. The overall rate performance demonstrates the high capacities in both low and high current rates of the prepared NiFe2O4 nanocage electrode. In Fig. 8, the TEM of NiFe2O4 electrode after 200 cycles at a current rate of 1 C reveals that the structure of this anode material can be retained well without breakage in the process of charge-discharge. Compared with the previously reported TMOs materials2433343536, the synthesized NiFe2O4 material in this work exhibits an enhanced electrochemical performance with our novel strategy. The unique hollow nanocage structures can shorten the length of Li-ion diffusion, which is beneficial to the rate performance. Furthermore, the hollow structure can offer a sufficient void space, sufficiently alleviating the mechanical stress caused by the volume change. Besides, the hybrid elements allow the volume change to take place in a stepwise manner during electrochemical cycle. As a result, the hierarchical hollow NiFe2O4 nanocage electrode can exhibit an extraordinary high electrochemical performance.

Bottom Line: The stable cyclic performance is obtained for all rates from 1 C to 10 C.Even when the current reaches 10 C, the capacity can also arrive at 652 mAhg(-1).Subsequently, a specific capacity of ca. 975 mAhg(-1) is recovered when the current rate reduces back to 1 C after 200 cycles.

View Article: PubMed Central - PubMed

Affiliation: School of Chemistry Science and Engineering, Yunnan University, Kunming 650091,Yunnan, China.

ABSTRACT
A hollow hybrid Ni-Fe-O nanomaterial (NiFe2O4) is synthesized using a precursor of metal-organic frameworks through a simple and cost-effective method. The unique hollow nanocage structures shorten the length of Li-ion diffusion. The hollow structure offers a sufficient void space, which sufficiently alleviates the mechanical stress caused by volume change. Besides, the hybrid elements allow the volume change to take place in a stepwise manner during electrochemical cycle. And thus, the hierarchical hollow NiFe2O4 nanocage electrode exhibits extraordinary electrochemical performance. The stable cyclic performance is obtained for all rates from 1 C to 10 C. Even when the current reaches 10 C, the capacity can also arrive at 652 mAhg(-1). Subsequently, a specific capacity of ca. 975 mAhg(-1) is recovered when the current rate reduces back to 1 C after 200 cycles. This strategy that derived from NMOFs may shed light on a new route for large-scale synthesis of hollow porous hybrid nanocages for energy storage, environmental remediation and other novel applications.

No MeSH data available.