Supporting Information Available High-performance Olivine NaFePO4 ...
Supporting Information Available
High-performance Olivine NaFePO4 Microsphere Cathode Synthesized by Aqueous Electrochemical Displacement Method for Sodium Ion Batteries Yongjin Fang, † Qi Liu, † Lifen Xiao, * ‡ Xinping Ai, † Hanxi Yang, † and Yuliang Cao *† †
Hubei Key Lab. of Electrochemical Power Sources, College of Chemistry and Molecular
Sciences, Wuhan University, Wuhan 430072, China. ‡
College of Chemistry, Central China Normal University, Wuhan 430079, China.
*CORRESPONDING AUTHOR: E-mail: [email protected]. Phone: +86-027-68754526 and Email: [email protected].
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Figure S1. Electrochemical characterization of the LiFePO4/C electrode: (a) Constant current charge/discharge profile of the LiFePO4/C electrode at 0.1 C (17 mA g-1) in 1 mol L−1 LiPF6/ EC: EMC: DMC (1:1:1 by vol.) solution and (b) The corresponding cycling performance (voltage window was 2.0–4.2 V versus Li+/Li); (c) Constant current charge/discharge profile of the LiFePO4/C electrode at 0.1 C in 1 mol L−1 Li2SO4 aqueous solution (voltage window was 0.6–0.7 V versus Ag/AgCl). The LiFePO4/C electrode shows a pair of flat voltage plateaus around 3.4 V (vs. Li+/Li) and a discharge capacity of 147 mAh g-1. After 75 cycles, the electrode almost holds the initial capacity, demonstrating excellent cycling stability. LiFePO4/C electrode in Li2SO4 aqueous solution delivers the same discharge capacity and voltage profile as that in the organic medium. These results indicate highly electrochemical Li ion intercalation/deintercalation activity in both organic and aqueous systems, and guarantee a highly structure-stable architecture to be used for transition from LiFePO4/C to NaFePO4/C.
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Figure S2. (a) The charge/discharge curves of the NaFePO4/C electrode in 1 mol L-1 NaPF6/EC: DEC (1:1 in vol.) solution at 0.5 C (1C = 154 mA g-1); (b) The corresponding XRD patterns of the NaFePO4/C electrode at different discharge depths as labeled in (a).
Table S1. Comparison of the cycle performance of the olivine NaFePO4 electrode. Reference 1 2 3 This work
Current rate 0.05 C 0.1 C 0.05 C 0.1
Cycle life 100 100 50 240
Capacity retention 71% 90% 88 90%
Table S2. Measured and calculated data based on the i-E curves of the NaFePO4/C electrode in 1 mol L-1 NaPF6/EC: DEC (1:1 in vol.) solution at various scan rates. C rate (mV/s)
ip1(A)
ln ip1
E1(V)
E1-E10' (V)
ip2(A)
ln ip2
E2(V)
E2-E20' (V)
0.5
3.63E-05
-10.2237
2.746
-0.128
6.96E-05
-9.57275
2.496
-0.277
1
5.46E-05
-9.81548
2.723
-0.151
7.50E-05
-9.49802
2.466
-0.307
2
7.70E-05
-9.47171
2.705
-0.169
8.36E-05
-9.38981
2.423
-0.350
0
0
* E1 ’=2.874 V, E2 ’=2.773 V, the values are taken from Boucher et al.[4]
References:
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[1] Wongittharom, N.; Lee, T.-C.; Wang, C.-H.; Wang, Y.-C.; Chang, J.-K., Electrochemical Performance of Na/NaFePO4 Sodium-Ion Batteries with Ionic Liquid Electrolytes. J. Mater. Chem. A 2014, 2, 5655-5661. [2] Zhu, Y.; Xu, Y.; Liu, Y.; Luo, C.; Wang, C., Comparison of Electrochemical Performances of Olivine NaFePO4 in Sodium-ion Batteries and Olivine LiFePO4 in Lithium-ion Batteries. Nanoscale 2013, 5, 780-787. [3] Oh, S.-M.; Myung, S.-T.; Hassoun, J.; Scrosati, B.; Sun, Y.-K., Reversible NaFePO4 Electrode for Sodium Secondary Batteries. Electrochem. Commun. 2012, 22, 149-152. [4] Boucher, F.; Gaubicher, J.; Cuisinier, M.; Guyomard, D.; Moreau, P., Elucidation of The Na2/3FePO4 and Li2/3FePO4 Intermediate Superstructure Revealing a Pseudouniform Ordering in 2D. J. Am. Chem. Soc. 2014, 136, 9144-9157.
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High-performance Olivine NaFePO4 Microsphere Cathode Synthesized by Aqueous Electrochemical Displacement Method for Sodium Ion Batteries Yongjin Fang, † Qi Liu, † Lifen Xiao, * ‡ Xinping Ai, † Hanxi Yang, † and Yuliang Cao *† †
Hubei Key Lab. of Electrochemical Power Sources, College of Chemistry and Molecular
Sciences, Wuhan University, Wuhan 430072, China. ‡
College of Chemistry, Central China Normal University, Wuhan 430079, China.
*CORRESPONDING AUTHOR: E-mail: [email protected]. Phone: +86-027-68754526 and Email: [email protected].
S-1
Figure S1. Electrochemical characterization of the LiFePO4/C electrode: (a) Constant current charge/discharge profile of the LiFePO4/C electrode at 0.1 C (17 mA g-1) in 1 mol L−1 LiPF6/ EC: EMC: DMC (1:1:1 by vol.) solution and (b) The corresponding cycling performance (voltage window was 2.0–4.2 V versus Li+/Li); (c) Constant current charge/discharge profile of the LiFePO4/C electrode at 0.1 C in 1 mol L−1 Li2SO4 aqueous solution (voltage window was 0.6–0.7 V versus Ag/AgCl). The LiFePO4/C electrode shows a pair of flat voltage plateaus around 3.4 V (vs. Li+/Li) and a discharge capacity of 147 mAh g-1. After 75 cycles, the electrode almost holds the initial capacity, demonstrating excellent cycling stability. LiFePO4/C electrode in Li2SO4 aqueous solution delivers the same discharge capacity and voltage profile as that in the organic medium. These results indicate highly electrochemical Li ion intercalation/deintercalation activity in both organic and aqueous systems, and guarantee a highly structure-stable architecture to be used for transition from LiFePO4/C to NaFePO4/C.
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Figure S2. (a) The charge/discharge curves of the NaFePO4/C electrode in 1 mol L-1 NaPF6/EC: DEC (1:1 in vol.) solution at 0.5 C (1C = 154 mA g-1); (b) The corresponding XRD patterns of the NaFePO4/C electrode at different discharge depths as labeled in (a).
Table S1. Comparison of the cycle performance of the olivine NaFePO4 electrode. Reference 1 2 3 This work
Current rate 0.05 C 0.1 C 0.05 C 0.1
Cycle life 100 100 50 240
Capacity retention 71% 90% 88 90%
Table S2. Measured and calculated data based on the i-E curves of the NaFePO4/C electrode in 1 mol L-1 NaPF6/EC: DEC (1:1 in vol.) solution at various scan rates. C rate (mV/s)
ip1(A)
ln ip1
E1(V)
E1-E10' (V)
ip2(A)
ln ip2
E2(V)
E2-E20' (V)
0.5
3.63E-05
-10.2237
2.746
-0.128
6.96E-05
-9.57275
2.496
-0.277
1
5.46E-05
-9.81548
2.723
-0.151
7.50E-05
-9.49802
2.466
-0.307
2
7.70E-05
-9.47171
2.705
-0.169
8.36E-05
-9.38981
2.423
-0.350
0
0
* E1 ’=2.874 V, E2 ’=2.773 V, the values are taken from Boucher et al.[4]
References:
S-3
[1] Wongittharom, N.; Lee, T.-C.; Wang, C.-H.; Wang, Y.-C.; Chang, J.-K., Electrochemical Performance of Na/NaFePO4 Sodium-Ion Batteries with Ionic Liquid Electrolytes. J. Mater. Chem. A 2014, 2, 5655-5661. [2] Zhu, Y.; Xu, Y.; Liu, Y.; Luo, C.; Wang, C., Comparison of Electrochemical Performances of Olivine NaFePO4 in Sodium-ion Batteries and Olivine LiFePO4 in Lithium-ion Batteries. Nanoscale 2013, 5, 780-787. [3] Oh, S.-M.; Myung, S.-T.; Hassoun, J.; Scrosati, B.; Sun, Y.-K., Reversible NaFePO4 Electrode for Sodium Secondary Batteries. Electrochem. Commun. 2012, 22, 149-152. [4] Boucher, F.; Gaubicher, J.; Cuisinier, M.; Guyomard, D.; Moreau, P., Elucidation of The Na2/3FePO4 and Li2/3FePO4 Intermediate Superstructure Revealing a Pseudouniform Ordering in 2D. J. Am. Chem. Soc. 2014, 136, 9144-9157.
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