Growth of NaO2 in Highly Efficient NaâO2 Batteries Revealed by

Subscriber access provided by UNIVERSITY OF CALGARY

Letter

The Growth of NaO2 in Highly Efficient Na-O2 Batteries Revealed by Synchrotron In Operando X-ray Diffraction Chenjuan Liu, David Rehnlund, William R Brant, Jiefang Zhu, Torbjörn Gustafsson, and Reza Younesi ACS Energy Lett., Just Accepted Manuscript • DOI: 10.1021/acsenergylett.7b00768 • Publication Date (Web): 15 Sep 2017 Downloaded from http://pubs.acs.org on September 15, 2017

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

ACS Energy Letters is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 13

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Energy Letters

The Growth of NaO2 in Highly Efficient Na-O2 Batteries Revealed by Synchrotron In Operando Xray Diffraction Chenjuan Liu, David Rehnlund, William R. Brant, Jiefang Zhu, Torbjörn Gustafsson, Reza Younesi* Ångström Advanced Battery Centre (ÅABC), Department of Chemistry-Ångström Laboratory, Uppsala University, Box 538, SE-75121, Uppsala, Sweden. AUTHOR INFORMATION Corresponding Author *E-mail: [email protected]

ABSTRACT: The development of Na-O2 batteries requires understanding the formation of reaction products, as different groups reported compounds such as sodium peroxide, sodium superoxide and hydrated sodium peroxide as the main discharge products. In this study, we used in operando synchrotron radiation powder X-ray diffraction (SR-PXD) to i) quantitatively track the formation of NaO2 in Na-O2 cells, and ii) measure how the growth of crystalline NaO2 is influenced by the choice of electrolyte salt. The results reveal that the discharge could be divided into two time regions and that the formation of NaO2 during the major part of the discharge

ACS Paragon Plus Environment

1

ACS Energy Letters

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 13

reaction is highly efficient. The findings indicate that the cell with NaOTf salt exhibited higher capacity than the cell with NaPF6 salt whereas the average domain size of NaO2 particles decrease during the discharge. This fundamental insight brings new information on the working mechanism of Na-O2 batteries.

TOC GRAPHICS

Non-aqueous alkali metal-air batteries such as Li-O2 and Na-O2 have attracted extensive attention as promising energy storage systems due to their high theoretical energy densities. Although the theoretical capacity is lower than that of a Li-O2 battery, the Na-O2 battery has triggered intensive interest owing to its higher energy efficiency due to lower overpotential during charge, higher rate capability and stability.1 However, further development of metal-O2 batteries is generally restricted by the lack of understanding of the working mechanism.2,3 In the case of non-aqueous Li-O2 battery, Li2O2 has been unequivocally detected as the main discharge product at the cathode.4 However, in the case of Na-O2, the situation is less clear due to the wide range of experimental observations.5,6 With similar standard potential of formation (E° NaO2 = 2.27 V vs. Na+/Na, E° Na2O2 =2.33 V vs. Na+/Na) but different number of electrons transferred,


2

Page 3 of 13

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Energy Letters

both NaO2 and Na2O2 (typically as the dehydrate Na2O2 · 2H2O) have been almost evenly identified as the discharge products.7-9 The underlying reason for this divergent result is not completely clear yet. Thus, further efforts are required to understand the key parameters governing the growth mechanism of the large NaO2 particles reported in number of studies.7,10,11 One of the major challenges in the evaluation of metal-O2 batteries is to find out to what extent parasitic reactions occur during cell cycling. Therefore, to characterize a metal-O2 cell, it is important to determine the amount of main reaction products formed/decomposed and how they correspond to the charge accumulated during discharge/charge. In this respect, in situ or in operando X-ray diffraction (XRD) can be a powerful tool for studying the evolution of crystalline NaO2 or Na2O2 in Na-O2 batteries, although until now, only few studies have applied this technique in metal-O2 cells.12-15 Here, we report a quantitative evaluation of NaO2 formation and investigate the critical impact of conducting sodium salts on the discharge capacity and the formation of NaO2 using in operando synchrotron radiation X-ray diffraction (SR-PXD). This enabled us to obtain a deeper insight into the complex mechanism of the Na-O2 cell. Figure 1 shows the diffraction patterns collected under in operando conditions during the first discharge of Na-O2 cells using two different salts, NaPF6 or NaOTf, dissolved in diglyme. The appearance of the diffraction peaks at 2θ ~4.32º, 6.11º and 7.16 º corresponding to (200), (220) and (331) reflections of NaO2 (ICSD # 87176) confirms the electrochemical formation of NaO2 during the discharge process. Here the reflections arising from Si were utilised as an internal reference.


3

ACS Energy Letters

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 4 of 13

Figure 1. 2-D waterfall plots of the diffraction patterns (λ = 0.207 Å) and the respective galvanostatic discharge profile collected under in operando conditions during the first discharge of Na-O2 cells using electrolytes of 0.5 M (a) NaPF6 (b) NaOTf in diglyme with a constant


4

Page 5 of 13

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Energy Letters

current of 0.075 mA/cm2. The diffraction patterns were collected every 15 min with 10 s exposure time.

Figure 2. The galvanostatic discharge profiles of Na-O2 cells with a constant current of 0.075mA/cm2 showing the evolution of NaO2 mass, (a) NaPF6, (b) NaOTf, and the evolution of the NaO2 average domain size (c) NaPF6 (d) NaOTf, respectively. Figure 2 displays the corresponding discharge profiles where the cell with NaPF6 shows a capacity of around 0.65 mAh, while the cell with NaOTf delivered more than double the capacity (~ 1.9 mAh) at the same cut of voltage and current density. To calculate the efficiency of the discharge reactions, the amount of NaO2 was determined from the weight ratio with the constant


5

ACS Energy Letters

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 6 of 13

and known quantity of Si via Rietveld refinement. When a Na-O2 cell is galvanostatically discharged, the theoretical increase in the mass of NaO2 would be equal to 2.05 mg/mAh if all of the exchanged electrons were used to generate NaO2 during discharge via the reaction Na+ + e- + O2 ⇋ NaO2. The detailed calculation is demonstrated in supporting information. Figure 2 indicates that the growth of NaO2 can be divided into two time regions. During the first discharge region (yellow color), the rate constant of NaO2 formation is far from ideal, and the efficiency of the discharge reaction is about 50-60% in both cells. In the second region (green color), the average rate constant of NaO2 formation is about 1.90 and 1.93 mg/mAh in the NaPF6 and NaOTf based cells, respectively, which is equal to 93% and 94% efficiency. Interestingly, the inefficient region is almost equal to 20-25% of the total capacity in both cells, while the highly efficient region is equal to 75-80% of total capacity in both cells. The low amount of crystalline NaO2 detected in the first region of discharge could originate from parasitic reactions, or from the formation of amorphous NaO2 or that the quantity of NaO2 was below the detection limit for SR-PXD at the beginning of discharge. Additionally, as shown in Figure S1, the quantity of NaO2 estimated by ex situ UV-vis spectroscopic quantitative method also showed that a high amount of NaO2 formed in both cells, however it is slightly lower than that detected by SR-PXD. The average apparent size of NaO2 primary particles formed during the discharge were demonstrated in Figure 2c-d. In the cell with NaPF6 salt, a trend of increasing NaO2 domain size from about 10 nm to about 200-250 nm along with the discharge could be observed (Figure 2c). However, in the cell with NaOTf salt (Figure 2d), the average domain size of the detected NaO2 is fluctuating in the beginning of the discharge (between capacity of 0 to 0.2 mAh), but then follows a general trend, decreasing from almost 100-150 nm to 30-50 nm. Our interpretation of


6

Page 7 of 13

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Energy Letters

the increase of the average domain size in the cell with NaPF6 salt is that NaO2 crystals are formed through an initial nucleation followed by continued crystal growth on the nucleation sites. Alternatively, continuous nucleation of new crystals during the discharge step where the new crystallites are smaller than the previously formed crystallites can explain the decrease in the domain size in the cell with NaOTf during discharge. Similar information regarding the growth of NaO2 was obtained when examining the morphology of discharge products. As shown in Figure 3, on the oxygen side of the electrode in the cell with NaPF6, a mixture of flakes and big cubic shaped particles (Figure 3a and Figure S2a, S2b) were formed, while in the cell with NaOTf salt NaO2 particles comprised of mainly cubic-shape at the end of discharge (see Figure 3b and Figure S2c, S2d). Other morphologies were also observed at the “separator side” of the electrode (Figure S2e, S2f). The different morphologies of NaO2 have also been reported in other studies, however, our results show that the morphology can be influenced by the chemistry of the electrolyte salt.16-18 The energy dispersive X-ray spectroscopy (EDS) results in the cell with NaPF6 (Figure 3a) indicated that the particles with different morphologies have a similar Na-O weight ratio, thus, all particles are likely composed of the same product. According to the XRD results, these particles should assigned to NaO2. Figure 3b shows that the cubic-shape discharge products formed in the cell with NaTOf. The EDS mapping results show that these cubic particles have a similar Na-O ratio as observed for the cell with NaPF6.


7

ACS Energy Letters

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 8 of 13

Figure 3. SEM and EDS data of the carbon paper cathode after discharge using (a) NaPF6 and (b) NaOTf salt. (a, left), morphology of the carbon paper cathode after discharge to 1.8V. (a, right) the elemental composition of the discharged products at different spots by EDS. (b, left top), morphology of the carbon paper cathode after discharge to 1.8V. (b, left bottom) the mapping sum of the elemental composition of the discharged products by EDS. (b, right) the


8

Page 9 of 13

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Energy Letters

mapping of elements from the SEM. All of the images were captured at the oxygen side of the cathode. Overall, the domain size of NaO2 crystals obtained from SR-XPD results and the morphology of NaO2 particles from SEM images reveal that the formation of NaO2 is influenced by the electrolyte anion selection. Several studies have reported that the Gutmann Donor Number (DN), a measure of Lewis basicity, of electrolyte solvents can strongly affect the Li+ stability in solution and solubility of O2-, and thus, the Li2O2 growth pathway and discharge capacities can be affected.19-21 A similar effect could be assumed when varying the DN of electrolyte salts.22 Typically, due to the similar and relatively low DN of most common anions used in lithium/sodium batteries, such as PF6-, BF4-, AsF6-, TFSI, the role of the DN in salt has seldom been considered.23 In this study, OTf- has 6-7 times higher DN than PF6- anions (DN of 16.9 and 2.5, respectively) 24 This consequently could be one of the possible reasons for the differences in morphology and domain size of NaO2 formed during discharge. However, Lutz et. al. have recently reported that the solvent with higher solubility of the NaO2 does not necessarily lead to higher capacities. Instead, the mass transportation of soluble discharge product, that is the solvent-solute interaction, appears to be crucial for the growth of NaO2 crystals.25 In this regard, the different discharge capacities in two different salt systems could likely be due to the strength of Na+-solvent complex in the electrolyte containing OTf- is stronger than the electrolyte comprising PF6-. Thus, a higher amount of Na-O2 complex can be stabilized in the electrolyte containing OTf- anion and a slow nucleation could result in formation of a larger number of cubic shape NaO2 particles. In the PF6- electrolyte, the ability to solvate Na-O2 complexes is weaker than that of OTf-, therefore the surface of cathode is quickly coved by smaller NaO2 particles at the beginning of discharge and a smaller capacity was observed.


9

ACS Energy Letters

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 10 of 13

In this study, the growth of NaO2 in Na-O2 batteries with high and low DN salts was investigated by in operando SR-PXD studies. The formation of NaO2 in Na-O2 cells is highly efficient (above 90%), and that the growth of NaO2 particles in a weak solvation ether solvent depends on the choice of conducting salts. Na-O2 cells provide higher capacity in OTf- anion electrolyte compared to the cells with PF6- anion electrolyte salt with lower DN. The domain size of NaO2 particles in Na-O2 cells with NaOTf decreases slightly during the discharge, while it significantly increases in the cell with NaPF6. Thus, the results explain how different morphologies of NaO2 particles – in particular big cubic NaO2 particles – form in Na-O2 cells. ASSOCIATED CONTENT Supporting Information. The following file is available free of charge. Experimental methods, UV-vis titration absorption spectra detecting the yield of NaO2 at the same discharge capacity in two different salt systems and supporting discussion, SEM of the discharge cathodes, schematic image of the homemade in operando Na-O2 cell, photo of a Na-O2 cell mounted on the SR-PXD, and a Rietveld refinement example of SR-PXD pattern from Fullprof (PDF) AUTHOR INFORMATION Corresponding Author *E-mail: [email protected] ORCID


10

Page 11 of 13

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Energy Letters

Chenjuan Liu: 0000-0002-8915-3032 David Rehnlund: 0000-0003-2394-287X William R. Brant: 0000-0002-8658-8938 Reza Younesi: 0000-0003-2538-8104 Notes The authors declare no competing financial interests. ACKNOWLEDGMENT The authors gratefully appreciate the support of the synchrotron measurement from DESY staff at beam-line PO2.1 in Hamburg, Germany. The authors thank the financial support by the Swedish

Research

Council,

Swedish

Energy

Agency,

StandUp

for

Energy,

Ångpanneföreningen´s Fundation for Research and Development, and China Scholarship Council. REFERENCES (1)

(2) (3) (4) (5)

(6)

Adelhelm, P.; Hartmann, P.; Bender, C. L.; Busche, M.; Eufinger, C.; Janek, J. From lithium to sodium: cell chemistry of room temperature sodium-air and sodium-sulfur batteries. Beilstein J. Nanotechnol. 2015, 6, 1016-1055. Aurbach, D.; McCloskey, B. D.; Nazar, L. F.; Bruce, P. G. Advances in understanding mechanisms underpinning lithium-air batteries. Nat. Energy 2016, 1, 16128. McCloskey, B. D.; Garcia, J. M.; Luntz, A. C. Chemical and Electrochemical Differences in Nonaqueous Li–O2 and Na–O2 Batteries. J. Phys. Chem. Lett. 2014, 5, 1230-1235. Luntz, A. C.; McCloskey, B. D. Nonaqueous Li-air batteries: a status report. Chem. Rev. 2014, 114, 11721-11750. Yadegari, H.; Sun, Q.; Sun, X. Sodium-Oxygen Batteries: A Comparative Review from Chemical and Electrochemical Fundamentals to Future Perspective. Adv. Mater. 2016, 28, 7065-7093. Zhao, N.; Li, C.; Guo, X. Long-life Na-O2 batteries with high energy efficiency enabled by electrochemically splitting NaO2 at a low overpotential. Phys. Chem. Chem. Phys. 2014, 16, 15646-15652.


11

ACS Energy Letters

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(7)

(8) (9)

(10)

(11)

(12)

(13)

(14)

(15)

(16)

(17)

(18)

(19)

(20)

Page 12 of 13

Bender, C. L.; Schroder, D.; Pinedo, R.; Adelhelm, P.; Janek, J. One- or Two-Electron Transfer? The Ambiguous Nature of the Discharge Products in Sodium-Oxygen Batteries. Angew. Chem., Int. Ed. Engl. 2016, 55, 4640-4649. Kim, J.; Lim, H. D.; Gwon, H.; Kang, K. Sodium-oxygen batteries with alkyl-carbonate and ether based electrolytes. Phys. Chem. Chem. Phys. 2013, 15, 3623-3629. Jian, Z.; Chen, Y.; Li, F.; Zhang, T.; Liu, C.; Zhou, H. High capacity Na–O2 batteries with carbon nanotube paper as binder-free air cathode. J. Power Sources 2014, 251, 466469. Hartmann, P.; Bender, C. L.; Vracar, M.; Durr, A. K.; Garsuch, A.; Janek, J.; Adelhelm, P. A rechargeable room-temperature sodium superoxide (NaO2) battery. Nat. Mater. 2013, 12, 228-232. Hartmann, P.; Bender, C. L.; Sann, J.; Durr, A. K.; Jansen, M.; Janek, J.; Adelhelm, P. A comprehensive study on the cell chemistry of the sodium superoxide (NaO2) battery. Phys. Chem. Chem. Phys. 2013, 15, 11661-11672. Pinedo, R.; Weber, D. A.; Bergner, B.; Schröder, D.; Adelhelm, P.; Janek, J. Insights into the Chemical Nature and Formation Mechanisms of Discharge Products in Na–O2 Batteries by Means of Operando X-ray Diffraction. J. Phys. Chem. C 2016, 120, 84728481. Ganapathy, S.; Adams, B. D.; Stenou, G.; Anastasaki, M. S.; Goubitz, K.; Miao, X. F.; Nazar, L. F.; Wagemaker, M. Nature of Li2O2 oxidation in a Li-O2 battery revealed by operando X-ray diffraction. J. Am. Chem. Soc. 2014, 136, 16335-16344. Lim, H.; Yilmaz, E.; Byon, H. R. Real-Time XRD Studies of Li-O2 Electrochemical Reaction in Nonaqueous Lithium-Oxygen Battery. J. Phys. Chem. Lett. 2012, 3, 32103215. Storm, M. M.; Johnsen, R. E.; Younesi, R.; Norby, P. Capillary based Li–air batteries for in situ synchrotron X-ray powder diffraction studies. J. Mater. Chem. A 2015, 3, 31133119. Yadegari, H.; Li, Y.; Banis, M. N.; Li, X.; Wang, B.; Sun, Q.; Li, R.; Sham, T.-K.; Cui, X.; Sun, X. On rechargeability and reaction kinetics of sodium–air batteries. Energy Environ. Sci. 2014, 7, 3747-3757. Liu, W.-M.; Yin, W.-W.; Ding, F.; Sang, L.; Fu, Z.-W. NiCo2O4 nanosheets supported on Ni foam for rechargeable nonaqueous sodium–air batteries. Electrochem. Commun. 2014, 45, 87-90. Hartmann, P.; Heinemann, M.; Bender, C. L.; Graf, K.; Baumann, R.-P.; Adelhelm, P.; Heiliger, C.; Janek, J. Discharge and Charge Reaction Paths in Sodium–Oxygen Batteries: Does NaO2 Form by Direct Electrochemical Growth or by Precipitation from Solution? J. Phys. Chem. C 2015, 119, 22778-22786. Johnson, L.; Li, C.; Liu, Z.; Chen, Y.; Freunberger, S. A.; Ashok, P. C.; Praveen, B. B.; Dholakia, K.; Tarascon, J. M.; Bruce, P. G. The role of LiO2 solubility in O2 reduction in aprotic solvents and its consequences for Li-O2 batteries. Nat. Chem. 2014, 6, 10911099. Aetukuri, N. B.; McCloskey, B. D.; Garcia, J. M.; Krupp, L. E.; Viswanathan, V.; Luntz, A. C. Solvating additives drive solution-mediated electrochemistry and enhance toroid growth in non-aqueous Li-O2 batteries. Nat. Chem. 2015, 7, 50-56.


12

Page 13 of 13

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Energy Letters

(21)

(22)

(23)

(24) (25)

Laoire, C. O.; Mukerjee, S.; Abraham, K. M.; Plichta, E. J.; Hendrickson, M. A. Influence of Nonaqueous Solvents on the Electrochemistry of Oxygen in the Rechargeable Lithium−Air Battery. J. Phys. Chem. C 2010, 114, 9178-9186. Burke, C. M.; Pande, V.; Khetan, A.; Viswanathan, V.; McCloskey, B. D. Enhancing electrochemical intermediate solvation through electrolyte anion selection to increase nonaqueous Li-O2 battery capacity. Proc. Natl. Acad. Sci. U. S. A. 2015, 112, 9293-9298. Younesi, R.; Veith, G. M.; Johansson, P.; Edström, K.; Vegge, T. Lithium salts for advanced lithium batteries: Li–metal, Li–O2, and Li–S. Energy Environ. Sci. 2015, 8, 1905-1922. Linert, W.; Camard, A.; Armand, M.; Michot, C. Anions of low Lewis basicity for ionic solid state electrolytes. Coord. Chem. Rev. 2002, 226, 137-141. Lutz, L.; Yin, W.; Grimaud, A.; Alves Dalla Corte, D.; Tang, M.; Johnson, L.; Azaceta, E.; Sarou-Kanian, V.; Naylor, A. J.; Hamad, S.et al. High Capacity Na–O2 Batteries: Key Parameters for Solution-Mediated Discharge. J. Phys. Chem. C 2016, 120, 20068-20076.


13

Growth of NaO2 in Highly Efficient NaâO2 Batteries Revealed by

Recommend Documents

Growth of NaO2 in Highly Efficient NaâO2 Batteries Revealed by