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Nanostructured Diamond Like Carbon Thin Film Electrodes for Lithium Air Batteries  

2011-09-23 13:59:33|  分类: 默认分类 |  标签: |举报 |字号 订阅

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Journal of The Electrochemical Society, 2011, Vol. 158, No. 10, pp. B1211–B1216
?2011 The Electrochemical Society. All rights reserved.


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Yin Yang,1,2 Qian Sun,1 Yue-Sheng Li,2 Hong Li,3 *and Zheng-Wen Fu1 *,z
1Shanghai Key Laboratory of Molecular Catalysts and Innovative Materials, Department of Chemistry and Laser Chemistry, Fudan University, Shanghai 200433, China
2Department of Material and Science, Fudan University, Shanghai 200433, China
3Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
(Submitted: 31 May 2011; revised: 15 July 2011; published online: 4 August 2011)

Nanostructured diamond like carbon (DLC) thin films were fabricated by radio frequency sputtering and their electrochemical behavior as air electrodes for Li-air batteries were investigated for the first time. These nanostructured DLC air cathodes presented high discharge plateaus around 2.7 V and large reversible capacities around 2318 mAh/g at the current rate of 220 mA/g. The reaction mechanism of DLC thin film electrodes of lithium air cells was revealed by ex situ Raman, Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) measurements. The formation of nanocrystalline Li2O2 and amorphous Li2CO3 was confirmed in the discharge products. Our results have demonstrated that DLC thin films with sp3-bonded carbon atoms due to their good cyclic performance and low polarization between discharging and charging profiles exhibit a promising candidate of air electrode materials for future lithium air batteries. ?2011 The Electrochemical Society



Contents
BODY OF ARTICLE
Experimental
Results and Discussions
Conclusion
Acknowledgments
REFERENCES
FIGURES
TABLES
FOOTNOTES

The lithium air battery has a high theoretical energy density due to the light weight of lithium metal and the fact that cathode material (O2) need not be stored in the battery. It has always been considered as an excellent potential candidate for electric propulsion application.1,2,3,4 A typical non-aqueous lithium air battery consists of a metallic lithium anode, an electrolyte comprising a dissolved lithium salt in an aprotic solvent and a porous O2-breathing cathode. Among these components, the architectures and compositions of the air cathode, which is composed of large surface area carbon particles, catalyst particles and polymer binders, play a key role in achieving high capacity for lithium air batteries. Due to the insolubility of the oxygen reduction reaction products (Li2O2 and Li2CO3) in the electrolyte, the precipitation of these compounds on the surface of the air electrodes contributes to the major voltage drops. Cheng et al. investigated the effect of carbon type on the performance of rechargeable lithium air batteries with Super P, Acetylene or Norit carbon black-supported manganese oxide catalysts and suggests that Norit carbon black is a better support than other carbons, which obtains a capacity of 4400 mAh/g at a current density of 70 mA/g.5 The discharge capacity data Xiao et al. also studied different carbon sources for their application in lithium air batteries operated in dry air environment.6 They found KB-based air electrode exhibited the highest specific capacity of 851 mAh/g at 0.05 mA/cm2. Tran et al. developed GDEs (gas-diffusion-electrode) to study the discharge capacities of different carbon materials.7 UMB7 carbon with much higher surface area in the large pores (pore size > 20 ?) exhibits the best performance for GDEs. Yang et al. prepared a novel MCF-C as the air cathode for lithium air battery. The specific capacity of MCF-C electrode has a significant increase comparing to super P carbon (2500 mAh/g at 0.1 mA/cm2, 40% higher than super P).8 Zhang et al. reported a new air electrode based on integrated carbon nanotube (CNT) and single-wall carbon nanotube (SWNT), which can deliver a specific capacity as high as 2540 mAh/g at 0.1 mA/cm2 discharge current density in lithium air battery, and the discharge capacity of the air cathode was found to strongly depend on the thickness of the air cathode, the discharge capacity decreased rapidly from 2550 mAh/g to 350 mAh/g at a fixed 0.1 mA/cm2 current density when the thickness of the electrode increased from 20 to 220 ?m, respectively.9 Most air cathodes are assembled in coin cells to be tested. A typical coin cell composed of a piece of separator placed onto the air cathode, an appropriate amount of electrolyte added to the separator, a piece of lithium disk, a stainless steel spacer and a coin cell cover. In addition, air cathodes with various ratios of carbon, catalyst and binder were reported in different research groups.5,10,11,12,13,14,15,16 These investigations of fundamental characteristics of the various carbon electrodes about their porosity, surface area, conducting, thickness and the chemical composition with different ratios with catalyst and binder provide necessary knowledge for the improvement of lithium air electrochemical performance. Consequently, some issues such as the nature of other type of carbons in lithium air cell and whether the discharge capacity can be further improved at the electrode thickness less than 1 ?m are needed to be addressed.

It is well accepted that thin film electrodes, which are free of additives and binders used in powder-based electrodes, and can be employed as an “ideal” system for the fundamental studies because they could yield greater insight into the intrinsic properties of the carbon electrode materials. In this work, a new type of lithium air cell based on diamond like carbon (DLC) thin film fabricated by rf sputtering carbon. The thickness of the cathode is less than 1 ?m, much smaller than previously air cathode ever reported, and can be controlled easily by the deposition time, which shows great potential for high-capacity air cathodes.

 


Experimental

The nanostructured DLC thin films were deposited by r.f. sputtering method with a carbon target (purity of 99.999%). The apparatus contained a vacuum chamber, which was evacuated to below 5 × 10?4 Pa by a mechanical pump and a turbo-molecular pump. Silicon substrates were heated at 200°C during the deposition process. The distance between the substrate and the carbon target was 6 cm. The pressure of Ar ambient gas was controlled at 1.5 Pa by a needle valve during deposition. The r.f. power was about 140 W. The deposition time was fixed about 3 h after pre-sputtering the target for 0.5 h to remove target contamination. The thickness of the thin film was determined by profilometry and scanning electron microscopy. Weight of thin film was directly obtained by subtracting the original substrate weight from total weight of the substrate and deposited thin film onto its surface, which were examined by electrobalance (BP 211D, Sartorius). The precision of the weight was ± 0.01 mg.

For electrochemical measurement, a conventional two-electrode cell was constructed in an argon ambient filled in glove box with the deposited thin film as the cathode (The geometric area of the air electrode is 1.2 cm2) and one sheet of high-purity lithium foil as the anode, respectively (Fig. 1). The model cell consisted of a H shape glass tube to separate positive and negative electrodes as well as two rubber plugs for sealing. The electrolyte was 1 M LiClO4 non-aqueous solution in ethylene carbonate (EC) and dimethyl carbonate (DMC) with a volume ratio of 1:1 (Merck). When the cells were cycled in the containers, the dried air diffused into the electrolyte solution spontaneously and supported the cycling of the cells. Charge-discharge measurements were performed at room temperature with a Land BT 1–40 battery test system.

Nanostructured Diamond Like Carbon Thin Film Electrodes for Lithium Air Batteries - 伯虎 - 锂空气电池文献 Figure 1.

The morphologies of the thin film electrodes were examined by a scanning electron microscopy (SEM) (Cambridge S-360). High resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED) measurements were carried out on a JEOL 2010 TEM at 160 kV accelerating voltage. Raman spectra were recorded at room temperature using micro-Raman system with a Dilor XY spectrometer including charge coupled device (CCD) detector. An argon ion laser (632.8 nm) was used as the excitation source. The spectra were measured in back-scattering geometry. The resolution was about 1 cm?1. Fourier transform infrared (FTIR) spectra were recorded on a Nicolet Nexus-470 spectrometer.

For the ex situ measurements, to avoid the exposure to oxygen or water, the model cells at different stages including the as-deposited, discharging to 2.0 V and charging to 4.5 V were dismantled in an Ar-filled glove box and the electrodes were rinsed in anhydrous, dimethyl carbonate (DMC) to eliminate residual salts. For TEM and SAED measurements, the active materials were scratched from the silicon substrate. The loose powders were then mixed with ethanol to prepare slurry, out of which one drop was taken, and deposited on a copper grid. To avoid exposure to oxygen or water, the grids were rapidly transferred into the chambers for cleanliness.

 


Results and Discussions

Figure 2 shows the galvanostatic cycling profiles of the cells between 2.0 and 4.5 V at the current densities of 220 mA/g (0.018 mA/cm2) and 1100 mA/g (0.092 mA/cm2), respectively. The gravimetric capacities were calculated based on the weight of DLC thin film (0.10 mg). The open circuit voltage (OCV) of the DLC air electrode/lithium cell was about 3.1 V. At a constant current of 220 mA/g, the cell exhibited a clear plateau at 2.6 V in the first discharging profile and this plateau shifted to around 2.7 V in the subsequent ones, while only slopes ranging from 3.8 to 4.5 V can be observed in all the charging curves (Fig. 2(a)). These results are in well agreement with the Li-air cell reported previously.2 The reduced polarization of the electrode in the subsequent cycles may be related to the improvement of the electrode/electrolyte interface before and after the electrochemical reactions. However, when the working current was set to 1100 mA/g, it can be observed that the discharge capacity of the cell significantly decreased while its polarization sharply increased (Fig. 2(b)). The first discharge capacities of DLC thin film electrode are about 2060 and 940 mAh/g at 220 and 1100 mA/g, respectively. Their reversible discharge capacities of above 2300 mAh/g at 220 and 1250 mAh/g at 1100 mA/g, respectively. These large discharge capacities are compatible with those obtained by various catalyst cathode electrodes and falls into the range from 1170 to 4700 mAh/g at a rate of 70 mA/g.5,10,17,18 These measurements can carried out up to 10 cycles with a capacity loss less than 1.6% per cycle at 220 mA/g and less than 3.3% per cycle at 1100 mA/g.

Nanostructured Diamond Like Carbon Thin Film Electrodes for Lithium Air Batteries - 伯虎 - 锂空气电池文献 Figure 2.

In order to further confirm the air electrode character of DLC thin film, a comparative experiment was designed and launched. Two needles were inserted into the rubber plug of the cell tube on the cathode side, one is used to bubble gas into the electrolyte, another is used as the outlet. As background test, pure argon was bubbled into the electrolyte of a cell to eliminate the residual oxygen. The charge-discharge performance of the cell was carried out for the first five cycles in argon filled glove box. Then the cell was taken out and the subsequent four charge-discharge cycles were tested. Figure 3 shows the first five discharge/charge cycles of the cells in the presence of argon ambient (black line) and the subsequent four cycles in the presence of air ambient (red line) filled in the cell tube respectively cycled between 2.0 and 4.5 V at the current density of 1200 mA/g (0.1 mA/cm2). In argon ambient, the charge/discharge curves are almost drop lines, indicating there are no Faraday processes during these cycles. The initial discharge capacity is about 80 mAh/g and the subsequent capacities are below 250 mAh/g. Interestingly, when the cathode was exposed in the air ambient, the discharge/charge curves of the cells and their discharge capacities are significantly different from those in argon ambient. A discharge plateau from 2.4 to 2.7 V appears and the discharge capacity of the cell dramatically increases to around 800 mAh/g. The charge plateaus at 4.2–4.5 V are observed. Apparently, the electrochemical behavior of the cell is dependent on the ambient gas. In addition, the discharge/charge curve of the cell at air is similar as that of Li/air cell. These results strongly support that nanostructured carbon thin film electrode is an air cathode.

Nanostructured Diamond Like Carbon Thin Film Electrodes for Lithium Air Batteries - 伯虎 - 锂空气电池文献 Figure 3.

To determine the structural and morphological modification of nanostructured carbon induced by Li uptake/removal, ex situ Raman, TEM, SAED, FTIR and SEM measurements were performed upon nanostructured carbon thin film at various states of the cell cycled between 2.0 and 4.5 V at a constant current of 110 mA/g (0.009 mA/cm2). Figure 4 shows Raman spectra of carbon thin film for the as deposited, after the cell initially discharging to 2.0 V, and after the cell initially charging to 4.5 V. There are two well-resolved peaks centered at 1332 cm?1 and 1580 cm?1 for the as-deposited thin film in the Raman shift ranges from 700 to 1600 cm?1, indicating a feature of the diamond like carbon (DLC). They can be assigned to the diamond band (D-band, sp3-bonding) and graphite band (G-band, sp2-bonding), respectively.19 Interestingly, one new peak emerging at around 795 cm?1 can be assigned to Raman shift of the O-O stretch in Li2O2.20 This indicates the conversion reaction of oxygen absorbed onto the surface of DLC thin film with lithium into a new product of Li2O2 after the cell is discharged to 2.0 V. In addition, the D and G bands of the discharged cathode become broader and have a red-shifted if comparing with those of the as deposited cathode. Previous studies suggested that the position and the line feature of D and G bands should be related with the stress in the carbon film.21 The discharge products of Li2O2 precipitate in the carbon to extrude near the carbons in the limited space can also result in the change of stress in the carbons after the discharging. Thus, the Raman spectra difference of the D and G bands between before and after the discharging provide another evidence on the discharge product is formed around the carbons. Upon charging process, lithium is gradually extracted from air electrode, the clear peak of Raman shift at 795 cm?1 disappears, indicating the decomposition of Li2O2 during the charging process.

Nanostructured Diamond Like Carbon Thin Film Electrodes for Lithium Air Batteries - 伯虎 - 锂空气电池文献 Figure 4.

In order to further reveal the composition and structure of carbon thin film electrode after the cell initially discharging to 2.0 V, and after the cell initially charging to 4.5 V, the ex situ TEM, and SAED techniques were utilized. For the as-deposited carbon thin film, some short moiré stripes could be found locally, indicating part of graphitized carbons in the TEM images shown in Fig. 5(a)–(1). SAED spectra in the region show two clear and weak rings [Fig. 5(b)–(2)]. They represent face-centered cubic structure of diamond carbon (JCPDS card no. 89-3441). Combined with Raman results (Fig. 4(a)), these results confirm that the as-deposited nanostructured carbon thin films are not structurally well ordered, and some diamond-like crystalline phases should exist in the amorphous carbon matrix. When the thin film electrode is discharged to 2.0 V, the TEM image and the SAED pattern are shown in Fig. 5(b)–(1) and (2), respectively. A thin film of discharge products precipitated and attached onto the carbon matrix, are labeled by the white arrow. SAED pattern in this region shows some discrete diffraction spots besides of the two diamond carbon diffraction rings. All d-spacings derived from the SAED spectra are shown in Table I. These discrete diffraction spots could be unambiguously indexed to the hexagonal Li2O2 (JCPDS 74-0115). It provides the strong evidence that Li2O2 is generated during discharge process with the absence of Li2O. This is consistent with Raman data. When the thin film electrode is fully charged to 4.5 V, the TEM image and the SAED patterns are shown in Fig. 5(c)–(1) and (2), respectively. The diffuse “halo” rings associated with d-spacings [Fig. 5(c)–(2)] appear. According to the SAED analysis shown in Table I, the d-spacings from the SAED spectra for thin film electrode after charging to 4.5 V agree well with those of diamond carbon (JCPDS card no. 89-3441), indicating the reconstruction of cubic structure of diamond carbon and the decomposition of Li2O2 under the applied potential during charging process.

Nanostructured Diamond Like Carbon Thin Film Electrodes for Lithium Air Batteries - 伯虎 - 锂空气电池文献 Figure 5.

The nanocrystallites of the products can be obtained by SAED, but without any information on the amorphous phase or nano-particles less than electron beam coherence length (1 nm). To further confirm the discharge products in our cell, the discharged air electrodes were characterized by FTIR spectroscopy as shown in Fig. 6. Thin films were deposited on the double-sided polishing silicon for FTIR tests. For the as deposited film, two sharp peaks centered at 1106 and 607 cm?1 can be assigned to anti symmetric stretching vibration of Si–O–Si quasi-molecule and substitution of silicon sites with carbon atoms,22,23 respectively. After discharging to 2.0 V, new peaks centered at 1436 and 867 cm?1 corresponding to the bending of the OCO<sub>2- group in Li2CO3 appear. The FTIR results provide a solid evidence that Li2CO3 is also formed during discharging process. It well agrees with Xiao's findings15 when the cell discharges to 2.0 V. They also suggest further discharging the cell to below 2.0 V causes the formation of more Li2CO3 and other lithium-containing carbonate species.

Nanostructured Diamond Like Carbon Thin Film Electrodes for Lithium Air Batteries - 伯虎 - 锂空气电池文献 Figure 6.

Figure 7 shows cross-sectional SEM images of DLC thin film for the as-deposited, after the cell initially discharging to 2.0 V, and after the cell initially charging to 4.5 V. The fresh cathode includes one layer of DLC onto the silicon substrate (thickness of 385 nm) as shown in Fig. 7(a). When the cell is discharged to 2.0 V, one layer of white region above the surface of DLC thin film (shown in the upper region of the dotted red line) is clearly observed. Its thickness is about 40–60 nm. Upon discharging process, lithium is gradually inserted into carbon cathode. It should be reasonably assumed that one white layer is a discharged product, this is most likely due to the formation of Li2O2 and Li2CO3 film, which was confirmed by Raman, SAED and FTIR data mentioned above. Interestingly, as shown in Fig. 7(c), the white region disappears after the cell charging to 4.5 V and exhibit single layer of DLC, indicating the recoverability of morphology.

Nanostructured Diamond Like Carbon Thin Film Electrodes for Lithium Air Batteries - 伯虎 - 锂空气电池文献 Figure 7.

It has been found that the cation of the conductive salt and the nonaqueous solvents strongly influence the oxygen reduction reaction (ORR) process and determine the discharge products.24,25,25,26 Recent researches revealed that the reduction products of O2 in the carbonate-based electrolyte could attack the carbonate solvents. As a result, the discharge products contain mainly lithium-containing carbonate species (such as Li2CO3, LiRCO3 et al.) with a little or even no lithium peroxide/oxide.15,27,28,29,30,31,32 In our Li-air cells, the absence of Li2CO3 diffraction rings in the SAED patterns and the presence of OCO<sub>2- bending peaks in the FTIR spectra identified the existence of amorphous Li2CO3 in the discharge products. In addition, no Li2CO3 was detected by Raman shift due to its very weak signal in our experimental condition. However, Raman and SAED results confirmed the formation of nanocrystalline Li2O2 after discharging to 2.0 V. It is convincible that nanocrystalline Li2O2 coexists with amorphous Li2CO3 in the discharge products after the cell discharges to 2.0 V.

Based on the ex situ Raman, TEM, SAED, FTIR and SEM results, Li2O2 and Li2CO3 as the products of the discharge reaction are formed onto surface of DLC thin film. Considering that the Li-air cells are cycled in dried air containing CO2, two origins may contribute to the formation of Li2CO3. One is the attack of carbonate solvents from O2 reduction products and the other involves the reaction between Li2O2 and CO2 from the dried air. The electrochemical reactions at nanostructured DLC thin film with lithium involving the following steps are proposed and the scheme is shown in Fig. 8

Nanostructured Diamond Like Carbon Thin Film Electrodes for Lithium Air Batteries - 伯虎 - 锂空气电池文献 Figure 8.

At cathode side during discharging

Li<sup>+ + O2 + 2e- --> Li2O21

nLi<sup>+ + O2 + EC/DEC + ne- --> Li2CO3 + sideproducts2

2Li<sub>2O2 + 2CO2 --> 2Li2CO3 + O23

At anode side during discharging:

2Li-2e<sup>- --> 2Li+4

The electrochemical reaction occurs at the contact interface of the liquid electrolyte and the nanostructured DLC thin films. During the electrochemical reaction, both Li ions and the dissolved oxygen should migrate through the liquid electrolyte and enrich at the surface of the nanostructured DLC thin film. The dissolved oxygen in the electrolyte absorbed on the nanostructured DLC thin films react with Li+ formed in anode side diffusing across the electrolyte to form Li2O2 and Li2CO3 at DLC thin film electrode side. With discharging, the discharge products sandwiched the nanostructured DLC and liquid electrolyte are gradually growing. When the product layer is thick enough (about 40–60 nm in the present case), the cathode reaction terminate due to the limitation of the diffusion and the solubility of dissolved oxygen or lithium ions.

In the present electrochemical cell with two glass tubes in an H form, oxygen source should mainly come from the dissolved oxygen in liquid electrolyte and the oxygen gas distributed the space between the rubber plugs and the electrolyte. According to the Bunsen coefficient alpha (The Bunsen coefficient is defined as the volume of gas which is absorbed by unit volume of solvent at the temperature of measurement under a partial pressure of 1 atm) of EC (0.0382 ml O2/ml liquid) and DEC (0.1773 ml O2/ml liquid),33 the alpha value in the mixed solvent system can be roughly predicted from the alpha values in the individual solvents using the following equation34:

ln <i>alphamix = Sigma xiln alphai5

where xi is the mole fraction of component i. The alpha of the present electrolyte solvent (EC/DEC, weight ratio 1:1) is 0.0817. The total mass of oxygen dissolved in the electrolyte of 4 mL is estimated to be approximately 0.0932 mg with O2 pressure of 0.2 atm in the air. Consuming of all the dissolved oxygen can provide the total capacity of 0.176 mAh when the discharge product is Li2O2, i.e. 1760 mAh/g for the DLC electrode based on the carbon weight of 0.10 mg. During the discharge process, oxygen in the electrolyte at the cathode side is gradually consumed, while the oxygen in air near to the electrolyte dissolves in the electrolyte simultaneously. The large discharge capacity of more than 2000 mAh/g at 220 mA/g and high discharge voltage plateau at around 2.7 V of the cell suggest that the dissolved oxygen in the electrolyte is sufficient to sustain the cathode reaction for the nanostructured DLC thin film electrode here (thickness around 385 nm, resistance ~260 Omega from Ac impedance). The sp3-bonded carbon atoms in DLC thin film as active sites for the oxygen-reduction reaction of the lithium air cell should be responsible for the good electrochemical performance of the lithium air cell with a high discharge capacity and a discharge voltage plateau.35 We tried to change the thickness of the as-deposited DLC thin film with less than 300 nm for the improvement of the electrochemical performance with higher discharge capacities and well cyclicality in lithium air cell. However, it was found that the discharge capacity become worse due to higher resistance in DLC thin film less than 300 nm. Therefore, the electrochemical cell of two glass tubes with an H form provide a useful method for the study to design and fabricate novel thin film materials less than 1 ?m as air cathode for lithium air cell. It is believed that the high accessible surface areas of nanostructured DLC thin films can also enhance the cathode reaction. In the future work, the electrochemical performance of the lithium air cell can be improved further after optimizing the electrode/electrolyte interface and by fabricating novel nanocomposite thin film materials with catalyst as air cathode.

 


Conclusion

In this work, a novel DLC thin film was prepared and used as the air cathode for lithium air battery. The DLC air cathode can deliver an initial discharge capacity of 2060 mAh/g at the current density of 220 mA/g with a capacity loss less than 1.6% per cycle for the first ten cycles. SAED pattern of DLC thin film electrode after the cell initially discharging to 2.0 V from the hexagonal Li2O2 were observed for the first time. It provides the strong evidence that Li2O2 is generated during discharge process with the absence of Li2O, which was also confirmed by the ex situ Raman measurement. FTIR spectra of discharged electrode confirmed the coexistence of amorphous Li2CO3 with nanocrystalline Li2O2 in the discharge products. The sp3-bonded carbon atoms in DLC thin film should play a key role in the good electrochemical performance of the lithium air cell with a high discharge capacity and a discharge voltage plateau.

 


Acknowledgments

This work was financially supported by Science & Technology Commission of Shanghai Municipality (08DZ2270500 and 09JC1401300) and 973 Program (No.2011CB933300) of China.

 


REFERENCES



 

References
K. M. Abraham and Z. Jiang, J. Electrochem. Soc. 143, 1 (1996). [ISI] first citation in article
G. Girishkumar, B. McCloskey, A. C. Luntz, S. Swanson, and W. Wilcke, J. Phys. Chem. Lett., 1, 2193 (2010). first citation in article
J. S. Lee, S. T. Kim, R. Cao, N.S. Choi, M. Liu, K. T. Lee, and J. Cho, Adv. Energy. Mater., 1, 34 (2011). first citation in article
A. Kraytsbergy and Y. E. Eli, J. Power Sources, 196, 886 (2011). first citation in article
H. Cheng and K. Scott, J. Power Sources, 195, 1370 (2010). [Inspec] first citation in article
J. Xiao, D. H. Wang, W. Xu, D. Y. Wang, R. E. Williford, J. Liu, and J. G. Zhang, J. Electrochem. Soc., 157, A487 (2010). first citation in article
C. Trana, X.-Q. Yang, and D. Qu, J. Power Sources, 195, 2057 (2010). [Inspec] first citation in article
X. H. Yang, P. He, and Y. Y. Xia, Electrochem. Commun., 11, 1127 (2009). [Inspec] first citation in article
G. Q. Zhang, J. P. Zheng, R. Liang, C. Zhang, B. Wang, M. Hendrickson, and E. J. Plichta, J. Electrochem. Soc., 157, A953 (2010). first citation in article
T. Ogasawara, A. Debart, M. Holzapfel, P. Novak, and P. G. Bruce, J. Am. Chem. Soc., 128, 1390 (2006). [MEDLINE] first citation in article
A. Debart, J. Bao, G. Armstrong, and P. G. Bruce, J. Power Sources, 174, 1177 (2007). first citation in article
A. Debart, A. J. Paterson, J. Bao, and P. G. Bruce, Angew. Chem., 120, 4597 (2008). first citation in article
Y.-C. Lu, Z. Xu, H. A. Gasteiger, S. Chen, K. Hamad-Schifferli, and Y. Shao-Horn, J. Am. Chem. Soc., 132, 12170 (2010). first citation in article
Y.-C. Lu, H. A. Gasteiger, M. C. Parent, V. Chiloyan, and Y. Shao-Horn, Electrochem. Solid-State Lett., 13, A69 (2010). first citation in article
J. Xiao, J. Hu, D. Wang, D. Hu, W. Xu, G. L. Graff, Z. Nie, J. Liu, and J.-G. Zhang, J. Power Sources, 196, 5674 (2011). first citation in article
W Xu, J. Xiao, D. Wang, J. Zhang, and J.-G. Zhang, J. Electrochem. Soc., 157, A219 (2010). first citation in article
M. Mirzaeian and P. J. Hall, J. Power Sources, 195, 6815 (2010). first citation in article
M. Eswaran, N. Munichandraiah, and L.G. Scanlon, Electrochem. Solid-State Lett., 13, A121 (2010). first citation in article
J. Robertson, Mater. Sci. Eng., R., 37, 129 (2002). first citation in article
H. H. Eysel, S. Thym, and Z. Anorg, Allg. Chem., 411, 97 (1975). first citation in article
J. Schwan, S. Ulrich, V. Batori, and H. Ehrhardt, J. Appl. Phys., 80, 441 (1996). first citation in article
D. R. Bosomworth, W. Hayes, A. R. L. Spray, and G. D. Watkins, Proc. R. Soc. London, Ser. A, 317, 133 (1970). first citation in article
R. C. Newman and J. B. Wills, J. Phys. Chem. Solids, 26, 373 (1965). [ISI] first citation in article
C. O. Laoire, S. Mukerjee, and K. M. Abraham, J. Phys. Chem. C, 113, 20127 (2009). first citation in article
C. O. Laoire, S. Mukerjee, and K. M. Abraham, E. J. Plichta, and M. A. Hendrickson, J. Phys. Chem. C, 114, 9178 (2010). first citation in article
C. O. Laoire, S. Mukerjee, E. J. Plichta, M. A. Hendrickson, and K. M. Abraham, J. Electrochem. Soc., 158, A302 (2011). first citation in article
F. Mizuno, S. Nakanishi, Y. Kotani, S. Yokoishi, H. Iba, Electrochemistry Proceedings of the 50th Battery Symposium in Japan, Kyoto, 78, 403 (2010) first citation in article
W. Xu, V. V. Viswanathan, D. Wang, S. A. Towne, J. Xiao, Z. Nie, D. Hu, and J. G. Zhang, J. Power Sources, 196, 3894 (2011). first citation in article
B. D. McCloskey, D. S. Bethune, R. M. Shelby, G. Girishkumar, and A. C. Luntz, J. Phys. Chem. Lett., 2, 1161 (2011). first citation in article
S. A. Freunberger, Y. Chen, Z. Peng, J. M. Griffin, L. J. Hardwick, F. Bard, P. Novak, and P. G. Bruce, J. Am. Chem. Soc., 133, 8040 (2011). first citation in article
A. K. Thapa, K. Saimen, and T. Ishihara, Electrochem. Solid-State Lett., 13, A165 (2010). first citation in article
A. K. Thapa and T. Ishihara, J. Power Sources, 196, 7016 (2011). first citation in article
J. Read, K. Mutolo, M. Ervin, W. Behl, J. Wolfenstine, A. Driedger, and D. Foster, J. Electrochem. Soc., 150, A1351 (2003). [ISI] first citation in article
R. Reid, J. Prausnitz, and B. Poling, The Properties of Gases and Liquids, 4th ed., p. 337, McGraw-Hill, New York (1987). first citation in article
E. Yoo and H. Zhou, ACS Nano, 5, 3020 (2011). first citation in article


FIGURES


Nanostructured Diamond Like Carbon Thin Film Electrodes for Lithium Air Batteries - 伯虎 - 锂空气电池文献 Full figure (45 kB)

Fig. 1. (Color online) The illustration of the construction of the lithium air model cell. First citation in article


Nanostructured Diamond Like Carbon Thin Film Electrodes for Lithium Air Batteries - 伯虎 - 锂空气电池文献 Full figure (81 kB)

Fig. 2. Galvanostatic cycling profiles of the DLC thin film/Li cells cycled between 2.0 and 4.5 V at the current densities of (a) 220 mA/g and (b) 1100 mA/g. First citation in article


Nanostructured Diamond Like Carbon Thin Film Electrodes for Lithium Air Batteries - 伯虎 - 锂空气电池文献 Full figure (58 kB)

Fig. 3. (Color online) The first five discharge/charge cycles of the cells filled in the presence of argon ambient (black line) and the subsequent four cycles in the presence of air ambient (red line) respectively cycled between 2.0 and 4.5 V at the current density of 1200 mA/g (0.1 mA/cm2). First citation in article


Nanostructured Diamond Like Carbon Thin Film Electrodes for Lithium Air Batteries - 伯虎 - 锂空气电池文献 Full figure (60 kB)

Fig. 4. (Color online) Raman spectra of carbon thin film for the as deposited, after the cell initially discharging to 2.0 V, and after the cell initially charging to 4.5 V. First citation in article


Nanostructured Diamond Like Carbon Thin Film Electrodes for Lithium Air Batteries - 伯虎 - 锂空气电池文献 Full figure (69 kB)

Fig. 5. (1) TEM and (2) SAED patterns of carbon thin film for (a) the as deposited, (b) after the cell initially discharging to 2.0 V, (c) after the cell initially charging to 4.5 V. First citation in article


Nanostructured Diamond Like Carbon Thin Film Electrodes for Lithium Air Batteries - 伯虎 - 锂空气电池文献 Full figure (55 kB)

Fig. 6. (Color online) FTIR spectroscopy of carbon thin film for the as deposited and after the cell initially discharging to 2.0 V. First citation in article


Nanostructured Diamond Like Carbon Thin Film Electrodes for Lithium Air Batteries - 伯虎 - 锂空气电池文献 Full figure (40 kB)

Fig. 7. (Color online) Cross-sectional SEM images of (a) the as-deposited, (b) discharging to 2.0 V, and (c) charging to 4.5 V DLC thin film electrodes. First citation in article


Nanostructured Diamond Like Carbon Thin Film Electrodes for Lithium Air Batteries - 伯虎 - 锂空气电池文献 Full figure (73 kB)

Fig. 8. (Color online) Schematic diagram of the reactions at nanostructured DLC thin film air electrode in Li/air battery First citation in article


TABLES

d-spacings (?) derived from SAED analysis of the as-deposited, first discharging to 2.0 V and first charging to 4.5 V of DLC thin film electrode. JCPDS standards of diamond carbon and Li2O2 are shown for references.
As-deposited
TWa Diamond carbon (89-3441)
Fd overline(3)m
2.07 2.06 (111)
1.26 1.26(220)
a=3.57 ± 0.01 a=3.57
First discharging to 2.0V
TW Diamond carbon (89.3441) TW Li2O2 (74-0115)
Fd overline(3)m P overline(6)
2.10 2.06(111) 3.83 3.83(002)
1.21 1.26(220) 1.58 1.57(110)
a=3.54 ± 0.09 a=3.57 a=3.15 ± 0.01 a=3.14
c=7.65 ± 0.01 c=7.65
First charging to 4.5V
TW Diamond carbon (89-3441)
Fd overline(3)m
1.99 2.06(111)
1.20 1.26(220)
a=3.43 ± 0.03 a=3.57
aTW: This work
First citation in article


FOOTNOTES

*Electrochemical Society Active Member.

zE-mail: zwfu@fudan.edu.cn


 

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