Boosting the Cyclic Stability of Aqueous Zinc-Ion Battery Based on Al

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Boosting the Cyclic Stability of Aqueous Zinc-Ion Battery Based on Al-doped V10O24·12H2O Cathode Materials Qian Li, Tongye Wei, Kaixuan Ma, Gongzheng Yang, and Chengxin Wang ACS Appl. Mater. Interfaces, Just Accepted Manuscript • Publication Date (Web): 22 May 2019 Downloaded from http://pubs.acs.org on May 28, 2019

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ACS Applied Materials & Interfaces

Boosting the Cyclic Stability of Aqueous Zinc-Ion Battery Based on Al-doped V10O24·12H2O Cathode Materials

Qian li1, Tongye Wei1, Kaixuan Ma1, Gongzheng Yang1*, Chengxin Wang1,2*

1State

Key Laboratory of Optoelectronic Materials and Technologies, School of

Materials Science and Engineering, Sun Yat-sen (Zhongshan) University, Guangzhou 510275, People’s Republic of China 2The

Key Laboratory of Low-carbon Chemistry & Energy Conservation of

Guangdong Province, Sun Yat-sen (Zhongshan) University, Guangzhou 510275, People’s Republic of China

*Correspondence and requests for materials should be addressed to C. X. Wang. Tel & Fax: +86-20-84113901 E-mail: [email protected]; [email protected]

1

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ACS Applied Materials & Interfaces 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

Keywords: Energy storage, Zinc-ion battery, vanadium oxide, Al doping, long life

Highlights: 1. We report the facile synthesis of Al-doped V10O24·12H2O and its application for aqueous zinc-ion battery cathode material. 2. Careful studies on the structural evolutions of electrodes during the cations de/insertion manifest the intercalation reaction mechanism and demonstrate the significantly enhanced structural stability of materials by the doping of Al. 3. Benefited from the doping of Al, the Al-doped V10O24·12H2O shows an excellent cycling performance of 98% capacity retention after 3000 cycles, which is superior to the 65% in the pure V10O24·12H2O.

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Abstract Rechargeable aqueous zinc-ion batteries (ZIBs) are considered an alternative energy storage system to lithium-ion battery because of its low price and high safety. However, the development of zinc-ion battery is limited by positive materials, which usually show poor cycling life due to the strong electrostatic interaction between divalent Zn2+ ions and crystal structure of materials. Developing a cathode material with stable structure upon cycling is still a big challenge for worldwide researchers. Doping foreign elements, which can solidify the lattice, is an effective approach to improve the structural stability of materials. However hardly any relatively research based on doping method for aqueous ZIBs has been reported. Here we develop an Al-doped layer material of V10O24·12H2O as cathode material for aqueous ZIBs. Benefited from the stable layered structure, the material exhibited an excellent cycling life with 98% capacity retention after 3000 cycles, which is much higher than the 65% in the pure V10O24·12H2O. The great enhancement on the cycle performance indicates that Al-doping can help building an advanced zinc-storage system.

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Introduction Lithium-ion batteries dominate worldwide secondary battery market nowadays, because of the high energy density and capacity.1-3 However, the lithium-ion battery cannot meet the requirement for grid-scale energy storage.4 The severe environmental and safety concern will be posed by the large format using of toxic and flammable organic electrolyte in lithium-ion batteries.5 Recently, the rechargeable multivalent aqueous batteries (Mg2+, Al3+, Zn2+) attracted extensive research enthusiasm.4, 6-9 And the unique aqueous system, which metals are used as anode materials directly, provides chances to achieve high energy density and environmentally friendly electrical energy storage (EES).7, 8 Among them, zinc metal anode has a high capacity density of 5855 mAh cm-3 and a suitable redox potential for aqueous electrolyte (-0.763 V versus standard hydrogen electrode).6, 10, 11 Benefited from these advantages, ZIBs provide particular promise for large-scale EES.6, 12, 13 However, the development of ZIBs is still plagued by the poor rate performance and short cycling life of positive materials.14, 15 Despite divalent zinc ions have a small ionic radius of 0.074 nm (the radius of Li+ is 0.069 nm), the electrostatic interaction between Zn2+ and lattice of host material is stronger than that of monovalent ions, and the electrostatic force will take more tough demands for host materials.16,

17

It is important to find a cathode

material with a stable structure. Vanadium oxides are highly feasible as host materials because of the reversible insertion of alkali ions or protons into their structure.18 What’s more, vanadium oxides layer materials are competent to work as the host material of zinc ions, the unique layer or bilayer structures which build through corner and edge sharing of V-O bonds are much more robust.18, 19 Recently, Zn0.25V2O5 nanobelts with a layer structure were reported as a high-capacity and long-life cathode material for ZIBs by Nazar et al.20 A high capacity of 260 mAh g-1 and long cycling life of 1000 cycles at 8 C rate were achieved thanks to the robust architecture. And it was found that water molecules will co-insert into the material with zinc ions, and the high radius of hydrate zinc ions will raise additional more risks for the materials. To stabilize the structure and extend service life, researchers have reported several approaches. Mai et al. demonstrated 4


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that chemically inserted water molecules into the layer of vanadium pentoxide can buffer the high charge density.21 In addition, sodium and lithium ions were introduced as pillars to be added into the layer structure to further improve the stability of vanadium oxide.22, 23 But related researches about ZIBs is still in its infancy stage, and a more efficient method is required. Doping foreign elements is regarded an effective method to improve the electrochemical performance of materials in lithium-ion batteries.24-26 And Al elements was expected to be a suitable dopant since it is nontoxic, cheap, and lighter than most transition metal elements.27 The chemical bond between Al ions and oxide ions are more stronger, which can reinforce lattice energy to protect the material from collapse and dissolution.27 For example, Al3+ ions will occupy the Mn3+ sites in LiMn2O4 and form stronger Al-O bonds that is expected to enhance the structure stability and inhibit the Jahn-Teller distortion.28 Besides, it was reported that the electrochemical performance of (Li[Li0.2Mn0.54Ni0.13Co0.13]O2),24 Li3V2(PO4)3,29 and VO230 were also enhanced by Al-doping. However, hardly any relative research about aqueous zinc-ion battery has been reported.31 despite there is an opportunity to further improve the stability of cathode materials in ZIBs. Here we report an Al-doped layer structure V10O24·12H2O as cathode material for aqueous zinc-ion battery. The doping of Al was verified by elemental mapping and XPS analyses. Electron microscopy tests (SEM, TEM) indicated the morphologies of materials in this paper have almost no impact on the electrochemical performances. The GITT coupled with AC impedance measurements proved that Al-doping had little effect on the diffusion rates of zinc ions. The XRD analysis was performed to investigate the influences of Al-doping, which was validated an effective way to enhance the structural stability of materials. Benefited from this, the electrochemical performance of V10O24·12H2O was greatly improved. Finally, the Al-doped V10O24·12H2O exhibits a long cycling life, which still delivers a high capacity of 294.5 mAh g-1 at 5 A g-1 after 3000 cycles and high capacity retention of 98%. By contrast, the pure V10O24·12H2O only exhibits 64% capacity retention after 3000 cycles at 5 A g-1. The distinct enhancement on electrochemical performances of 5



Al-doping materials indicates that doping is effective in ZIBs. This result surely provides a potential chance for further development of ZIBs.

Results and Discussion The XRD patterns (Fig 1a) of the two materials can be well indexed with V10O24·12H2O (PDF#25-1006). The Al-doped material has not any obvious peak position shift which probably because of the low doping level.24, 32 The SEM, TEM and HRTEM images (depicted as Fig 1b, S1a, and S2) show that the slightly curly V10O24 nanobelts with a uniform size of 0.2 μm in width and tens micrometers in length are well dispersed. The layer with an interplanar spacing of 0.182 μm, depicted in Fig S2, is consistent with (-518) plane and match well with XRD results. As for Al-doped V10O24·12H2O a lot of thinner belts mix together to synthesize the uniform urchin-like morphology (Fig 1c, 1d and S1b). The scanning TEM (STEM) image and correspond elemental mapping images of V10O24-Al (Fig 1e) show the Al, V, and O are uniformly distributed. And Fig 1f and 1g are the EDX spectra and XPS spectroscopy of Al-doped V10O24·12H2O respectively. And inset of Fig 1f shows the doping amount of Al elements, the element contents of V and Al are 24.58% and 1.57% respectively which indicates a low doping level. Combining with elemental mapping, it is sure that Al is successfully doped into V10O24·12H2O. The HRTEM image of Al-doped V10O24·12H2O (Fig S3) presents a layer spacing of 1.39 nm belong to (002) plane. To test the electrochemical performances of two materials, CR-2032 type coin cells were manufactured with a zinc foil anode, 3 mol L-1 Zn(CF3SO3)2 solution as electrolyte and a glass fiber separator. The first scan of CV tests for V10O24 is different compared to following cycles. As Fig 2a shows, an unusual peak around 1.4-1.6 V means the irreversible reaction occurs at the first charge progress. As Fig 2b shows, the charge/discharge profiles match well with the CV curves. And in the next two cycles, two pairs of redox peaks, which locate at 0.58/0.79 V and 0.97/1.06 V respectively, can be obtained. The Al-doped material also shows two pairs of redox peaks in second cycle at 0.59/0.72 V and 0.96/1.03 V respectively (Fig 2d), which has 6


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no changes in position. However, Al-doped materials is different in the shape of CVs test. V10O24 is kind of layer material and the Al3+ may doping into the layer structure to form strong Al-O bonds. Zinc ions were transported and storage between the layers which may be slower by electrostatic interaction between Al3+ and Zn2+ ions as well as Al-O bonds. CVs measurements, which reflect the zinc ions (de)intercalation in the materials, will be different after Al doping. Little changes in shape can be observed of the four peaks for next two cycles, which correspond to the intercalation and deintercalation of Zn(H2O)m2+ groups, proves a good reversibility.20,

22

And the

discharge/charge profiles has not differences with pure V10O24 either as Fig 2e shows. The hysteresis of redox peaks for both two materials in the first cycle may due to the inactivation of materials. Rate performance of the materials is illustrated in Fig 2c, and 2f, to activate the battery 100 cycles charge/discharge at 1 A g-1 were firstly request, then the current arise from 200 mA g-1 to 5 A g-1 and decrease to 200 mA g-1 gradually. The specific capacity of Al-doped material at 0.2, 0.5, 1, 2, 5 A g-1 are 415, 370, 327, 284, 232 mAh g-1 respectively compared with 431, 337, 272, 221, 166 mAh g-1 of pure V10O24. It's worth mentioning that the pure V10O24 shows higher capacity than Al-doped V10O24 at first, but the nature of instability of structure causes the fast loss of capacity. Finally the Al-doped material still has a capacity of 368mAh g-1 compare with a low capacity of 298 mAh g-1 for pure V10O24. Long term galvanostatic tests were requested to further indicates the stability of two materials as Fig 2g, and S4 display. The pure V10O24 and Al-doped V10O24 show extremely different performance. The pure V10O24 has delivered high capacity of 310 mAh g-1 and 390 mAh g-1 at 5 A g-1 and 1 A g-1 respectively, and a fast fade of the capacity indicates the system is not stable. Fortunately, Al-doped V10O24 shows a great enhancement, the battery obtained 355 mAh g-1 capacity and still keep 89% retention of the capacity at 1 A g-1 after 300 cycles, even at 5 A g-1 the Al-doped V10O24 delivered 301 mAh g-1 capacity and keep 98% of the capacity after 3000 cycles, compare with 75% retention at 1 A g-1 after 300 cycles and 65% retention at 5 A g-1 after 3000 cycles of pure V10O24. The charge/discharge profiles shown as Fig S5, and S6 of the two materials can also confirm the big differences of the stability. Compare with the state-of-the-art 7



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materials for aqueous zinc-ion battery, Al-doped V10O24 also shows inspiring power densities which can easily observed in Fig S7.20,

33-35

The reasons of good

electrochemical performance need to be further investigated. The electron microscopy studies were carried out to study morphology evolution of the V10O24 and Al-doped V10O24 electrodes. As Fig 3a shows, no obviously changes in morphology can be observed as the V10O24 electrode discharged to 0.3 V and the layer with 0.34nm spacing can be indexed with lattice fringe of (111) planes show as Fig S8. Meanwhile the elemental mapping analysis (Fig 3b) illustrates that V, O and Zn elements are homogeneously distributed in electrode and the strong signal of zinc proves that zinc ions have inserted into the material. However, when charged to 1.6 V the nanobelt morphology of V10O24 electrode changed to small nanosheet as Fig 3c displays. According to previous report, continuous extraction of Zn(H2O)62+ groups will produce electrostatic repulsion between the interlayer to release the stress of structure.20,

36

Affected by electrostatic force, the d spacing of interlayer will be

enlarged and the skeleton bending vibration will be accelerated, which finally cause the slide of the V-O layer.36 As a result, the nanobelts will be destroyed and change to sheet like morphology when charged to 1.6 V. Fig S9 displays an interlayer with 0.57nm spacing at fully charge state which can be corresponded to (-202) face. The elemental mapping images show the distribution of V, O and Zn elements, attenuation of zinc signals indicates the extraction of zinc ions shows as Fig 3d.37 Similar phenomenon can be seen from Al-doped V10O24 electrodes, the electrodes will also change to small nanosheets morphology after firstly discharge/charge progress shown as Fig 3e, 3f, 3h, and 3i respectively, which indicates Al-doping has little influence on evaluation of morphology. One point is that the morphology of Al-doped V10O24 will be destroyed and change to nanosheets when firstly discharged to 0.3 V, because it has smaller size than pure V10O24 originally which is more fragile. And the strong electrical force between divalent zinc ions and the structure causes the changes of morphology. The elemental mapping images of Al-doped V10O24, as Fig 3g and 3j show, indicate the distribution of V, O, Al, and Zn at 0.3 V/1.6 V respectively. And the EDX spectroscopy can further indicates the insertion/extraction of two materials 8


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as Fig S10, and S11. Both two materials will maintain nanosheets morphology in the second cycles as Fig S12 shows. That is, the changes of morphology are irreversible. The electron microscopy studies can be summarized as follow, Al doping will not affect the morphology evolution during charge/discharge progress, no matter what morphology of the original materials are they will be destroyed and change to small nanosheets after first cycle. Actually, the morphology is not the main points for the electrochemical performance of V10O24. The galvanostatic intermittent titration technique (GITT) was performed to calculate the diffusion coefficient of the zinc ions (DZn2+GITT) in the two materials. The result was depicted as Fig S13, both two materials were calculated around 10-10 cm2 s-1 by the GITT measurement and the diffusion coefficient of pure material is a little higher than Al-doped V10O24. However, they are all two magnitude higher than that of lithium ions translate in LiFePO4 in an organic system,20 which indicates a good rate performance. Meanwhile the electrochemical impedance spectroscopy studies match well with the GITT test. Combining the GITT and electrochemical impedance spectroscopy results, it is easily to find that Al-doping has slight effects on the transport of zinc ions in materials. And the electrochemical performance of V10O24 is not depended on the diffusion of zinc ions. A CV test was performed to examine the capacity distribution of capacitive contribution and diffusion-control. The result is depicted as Fig S14, both two materials are dominated by capacitor-like kinetics when raise the scan rate to 0.5 mV s-1, which will be in favor of good rate performance. More evidence should to be carried out to find the real reasons for substantial improvement in cycling stability. The ex-situ XRD test was performed to investigate the discharge/charge mechanisms of V10O24. We collected every stage of XRD patterns for the first two cycles as shown in Fig 4a. The material was initial inactive, when the zinc ions intercalate/extract the lattice, the layer structure of the V10O24 get more complete. Two peaks located at 12.78° and 19.37°, which can be indexed to (004) and (006) faces respectively, emerge and get sharper gradually with the battery firstly charge from 1.3 V to 1.6 V and keep stable as the battery charge to 1.6 V in next working 9



cycles. The result corresponds well to the CV test (Fig 2a), there is an irreversible reaction during the first scan. It is easily to understand this phenomenon, zinc ions will transport and storage through (00l) face, to better adapt the insertion of Zn(H2O)62+ groups, the layered structure of material needs to be further activated during first cycle.12,

20

When zinc ions were firstly extract from the structure, the

pathway was completely opened, so the narrow peaks of (004) and (006) faces were observed. In other word, the layer structure is crucial for the insertion and extraction of zinc ions. The main peak around 7.0° which define as the (002) face, as well as (004) and (006) peaks of the material show regular changes. The peaks have a right shift and get broaden to almost disappear as the battery discharge to 0.3 V. The continue insertion of zinc ions would reduce electrostatic repulsion between the interlayer oxygen ions of VO6 units, and pin the VO6 layer together which caused the shrinkage of the layer structure.20 And these peaks show contrary changes when charge to 1.6 V. Undoubtedly, the strong electrostatic interaction between structure and divalent zinc ions will destroy the lattice of structure, and this is the major reason for the decline in capacity of materials. The rest peaks in the range of 40° to 65° will shift to left and then go back to original place with the discharge/charge progress going on. The reduction of V5+ because of the insertion of zinc ions will take responsibility for the expansion of interlayer space.13, 38 XPS spectroscopy was carried out to investigate chemical state changes during discharge/charge progress of V10O24 for the first cycle. The survey spectra of electrodes for every stage of V10O24 and pristine Al-doped V10O24 are illustrated as Fig S15. And the insertion of zinc ions was well proved by Fig S16. Two high-intensity peaks can be observed at discharged state (0.3 V) which corresponds to Zn2p spectra. By the contrast, the low peaks, shown as charged state (1.6 V), may come from irreversible reaction and surface residual of the electrode.13 The results match well with elemental mapping results (Fig 3). The peaks at 517.6 eV and 516.7 eV correspond to V5+ and V4+ respectively shown as Fig 4b. The increasing of the peak at 516.7 eV of discharged state indicates the reduction of V5+, which caused by the insertion of zinc ions. And when the battery charged to 1.6 V which means the zinc 10


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ions had extracted from the materials, the V4+ was oxidized to V5+. The O1s region can be divided into three peaks at 530.3 eV, 531.2 eV and 532.4 eV which correspond to O2-, OH-, and H2O respectively shown as Fig 4c. And the enhancement of peaks at 532.4 eV indicates the H2O molecules will form Zn(H2O)62+ groups with zinc ions and incorporate into the structure together.20 The results of XPS prove the insertion of Zn(H2O)62+ match well with XRD analysis. To find out real reasons for the great increasement of electrochemical performance after Al-doping, XRD spectra for electrodes after long-term cycle was performed shown as Fig 4d. After working for 21 days and then charged to 1.6V, (collected at 100mA g-1 after 140 cycles) the (002) and (004) peaks of V10O24 become broader and attenuation, which means the layer structure was almost destroyed by continuous insertion/extract of zinc ions. Obviously zinc ions become more difficult to transport and install in the material without a complete lamellar structure. However, the Al-doped electrode still keep a good crystallinity and the (002) peaks still show a high intensity which indicates the structure of Al-doped V10O24 had not been destroyed completely. The image inserted in Fig 4d further show the influence of structure stability on long-term cycle. Benefited from the stable layer structure, the Al-doped V10O24 show a higher capacity retention. And long cycle life of electrodes indicates the lattice energy was reinforced by Al-doping. Combining with electron microscopy, XRD, and XPS tests, we can make out the zinc storage mechanisms and the influence of Al-doping. Zn(H2O)62+ groups will transport through (00l) faces of the layer structure of V10O24 electrode, the material will be activated after firstly discharge/charge progress. Due to the rapid insertion and release of zinc ions, the original morphology will finally break and change to small nanosheets because of the strong electrostatic interaction between materials and zinc ions. However, the structure of V10O24 cannot meet the requirement for long-term cycle of insertion and extraction of zinc ions, and the collapse of the lamellar structure caused a significant decline in battery performance. The layer spacing of V10O24 (calculated about 12.5Å in XRD patterns for (002) face) is not much bigger when compare with the diameter of Zn(H2O)62+ groups (4.3Å). 4 So, continuous insertion 11



and release of Zn(H2O)62+ groups can cause great damage to the structure and lead to a fast degradation of capacity. Fortunately, the stability of the structure is greatly improved by doping aluminum, which will further improve the chemical performance. The Al-doped electrode can keep complete lamellar structure even after working for 21 days (collected at 100mA g-1 after 140 cycles). And GITT tests proved Al-doping has little influence on the diffusion of zinc ions in the material, because of the mixed valence states of vanadium oxides both two materials keep a good electrical conductivity.39 All the evidence indicates that the electrochemical performance of V10O24 electrode was enhanced by Al-doping because of the more robust architectures.

Conclusion In summary, we successfully synthesized Al-doped layered V10O24 as cathode material for aqueous ZIBs. XRD analyses suggested that Zn(H2O)62+ groups diffused along the (00l) planes of materials during charge/discharge processes. The strong electrostatic interaction between divalent zinc ions and crystal structure would cause the structure collapse of material, which further leaded to poor electrochemical performances. Fortunately, the structural stability was enhanced by Al-doping method, which was validated by electron microscopy, XRD, and XPS tests. The robust structure was in favor to a better electrochemical performance. As a result, the Al-doped V10O24 delivered a high capacity of 355 mAh g-1 at 1 A g-1 and good capacity retention of 89% after 300 cycles. The material still demonstrated a high capacity of 301 mAh g-1 at 5 A g-1 and a high capacity retention of 98% after 3000 cycles. By comparison, pure V10O24 showed poor cycle life that only kept 74% and 64% of capacities after 300 cycles at 1 A g-1 and 3000 cycles at 5 A g-1, respectively. The significant improvement on performance of long-term cycle indicates a good chance to further develop advanced cathode materials of ZIBs by Al-doping.

Experimental section Synthesis: To synthesize pure V10O24, 1.0 g commercial V2O5 powder and 1.0 g 12


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glucose were added into deionized water of 40 ml, and the mixture was then heated under reflux at 100 °C for 12h. Finally, the dark green powder was got after washed in water and alcohol then dried at 70 °C for 12h. In a typical synthesis, 585 mg NH4VO3 was dissolved in 185 ml deionized water at 80 °C then 15 ml HCl of 1 mol L-1 was added to adjust the pH value. And 75 ml solution was transferred into a 100 ml Teflon-lined autoclave to added 566 mg Aluminum chloride. The final precursor was heated to 180 °C for 12h. Washed by deionized water, the product was obtained after 12 hours’ drying at 70 °C. Characterization: The XRD pattern was collected on Rigaku Co. (Japan) which uses Cu Kα radiation at a generator voltage of 40 kV. The electron microscopy tests were performed on a JSM-7001F type scanning electron microscope (SEM, JEOL, 15 kV) and a transmission electron microscopy (TEM, FEI Tecnai G2 F30, 300 kV). The XPS information was collected on PerkinElmer PHI 1600 ESCA spectrometer. Electrochemical test: The electrochemical performance of the materials was evaluated by CR2032 coin-type cells. And 3 mol L-1 Zn(CF3SO3)2 solution was used as electrolyte, zinc foil was counter electrode, and a glass fiber (GF/A, whatman) was employed as separator. To prepare electrodes, materials were mixed with carbon black and polyvinylidene fluoride with a weight ratio of 7:2:1, which was then dissolved in N-methyl-2-pyrrolidone solvent. The slurries were coated on a graphite paper and dried at 90 °C for 12h. Finally, the electrodes were cut into wafers with 12mm diameters and the weight of the active materials of each electrode was around 2 mg. The whole manufacturing processes were performed in air at ambient temperature. The CV tests and Galvanostatic charge-discharge analysis were performed by electrochemistry workstation (CHI660, CH Instruments, China) and battery test system (Newware, Shenzhen), respectively.

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Batteries as Cathodes. Nano Lett. 2018, 18, 2402-2410. 14. Zhu, C.; Fang, G.; Zhou, J.; Guo, J.; Wang, Z.; Wang, C.; Li, J.; Tang, Y.; Liang, S. Binder-Free Stainless Steel@Mn3O4 Nanoflower Composite: A High-Activity Aqueous Zinc-Ion Battery Cathode with High-Capacity and Long-Cycle-Life. J. Mater. Chem. A. 2018, 6, 9677-9683. 15. Tang, B.; Fang, G.; Zhou, J.; Wang, L.; Lei, Y.; Wang, C.; Lin, T.; Tang, Y.; Liang, S. Potassium Vanadates With Stable Structure and Fast Ion Diffusion Channel as Cathode for Rechargeable Aqueous Zinc-Ion Batteries. Nano Energy. 2018, 51, 579-587. 16. Huang, J.; Wang, Z.; Hou, M.; Dong, X.; Liu, Y.; Wang, Y.; Xia, Y. Polyaniline-Intercalated Manganese Dioxide Nanolayers as A High-Performance Cathode Material for An Aqueous Zinc-Ion Battery. Nat. Commun. 2018, 9, 2906. 17. Zhang, N.; Dong, Y.; Jia, M.; Bian, X.; Wang, Y.; Qiu, M.; Xu, J.; Liu, Y.; Jiao, L.; Cheng, F. Rechargeable Aqueous Zn-V2O5 Battery with High Energy Density and Long Cycle Life. ACS Energy Lett. 2018, 3, 1366-1372. 18. Chernova, N. A.; Roppolo, M.; Dillon, A. C.; Whittingham, M. S. Layered Vanadium and Molybdenum Oxides: Batteries and Electrochromics. J. Mater. Chem. 2009, 19, 2526. 19. Yue, Y.; Liang, H. Micro- and Nano-Structured Vanadium Pentoxide (V2O5) for Electrodes of Lithium-Ion Batteries. Adv. Energy Mater. 2017, 7, 1602545. 20. Kundu, D.; Adams, B. D.; Duffort, V.; Vajargah, S. H.; Nazar, L. F. A High-Capacity and Long-Life Aqueous Rechargeable Zinc Battery Using A Metal Oxide Intercalation Cathode. Nat. Energy. 2016, 1, 16119. 21. Yan, M.; He, P.; Chen, Y.; Wang, S.; Wei, Q.; Zhao, K.; Xu, X.; An, Q.; Shuang, Y.; Shao, Y.; Mueller, K. T.; Mai, L.; Liu, J.; Yang, J. Water-Lubricated Intercalation in V2O5.nH2O for High-Capacity and High-Rate Aqueous Rechargeable Zinc Batteries. Adv. Mater. 2017, 30, 1703725. 22. He, P.; Zhang, G.; Liao, X.; Yan, M.; Xu, X.; An, Q.; Liu, J.; Mai, L. Sodium Ion Stabilized Vanadium Oxide Nanowire Cathode for High-Performance Zinc-Ion Batteries. Adv. Energy Mater. 2018, 8, 1702463. 15



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23. Yang, Y.; Tang, Y.; Fang, G.; Shan, L.; Guo, J.; Zhang, W.; Wang, C.; Wang, L.; Zhou, J.; Liang, S. Li+ Intercalated V2O5·nH2O with Enlarged Layer Spacing and Fast Ion Diffusion as An Aqueous Zinc-Ion Battery Cathode. Energy Environ. Sci. 2018, 11, 3157-3162. 24. Luo, M.; Zhang, R.; Gong, Y.; Wang, M.; Chen, Y.; Chu, M.; Chen, L. Effects of Doping

Al

on

The

Structure

And

Electrochemical

Performances

of

Li[Li0.2Mn0.54Ni0.13Co0.13]O2 Cathode Materials. Ionics. 2017, 24, 967-976. 25. Wang, J. L.; Li, Z. H.; Yang, J.; Tang, J. J.; Yu, J. J.; Nie, W. B.; Lei, G. T.; Xiao, Q.

Z.

Effect

of

Al-Doping

on

The

Electrochemical

Properties

of

A

Three-Dimensionally Porous Lithium Manganese Oxide for Lithium-Ion Batteries. Electrochim. Acta. 2012, 75, 115-122. 26. Dianat, A.; Seriani, N.; Bobeth, M.; Cuniberti, G. Effects of Al-Doping on The Properties of Li–Mn–Ni–O Cathode Materials for Li-Ion Batteries: An Ab Initio Study. J. Mater. Chem. A. 2013, 1, 9273. 27. Xiao, L.; Zhao, Y.; Yang, Y.; Cao, Y.; Ai, X.; Yang, H. Enhanced Electrochemical Stability of Al-doped LiMn2O4 Synthesized by A Polymer-Pyrolysis Method. Electrochim. Acta. 2008, 54, 545-550. 28. Ding, Y. L.; Xie, J.; Cao, G. S.; Zhu, T. J.; Yu, H. M.; Zhao, X. B. Enhanced Elevated-Temperature Performance of Al-Doped Single-Crystalline LiMn2O4 Nanotubes as Cathodes for Lithium Ion Batteries. J. Phys. Chem. C. 2011, 115, 9821-9825. 29. Cho, A. R.; Son, J. N.; Aravindan, V.; Kim, H.; Kang, K. S.; Yoon, W. S.; Kim, W. S.; Lee, Y. S. Carbon Supported, Al Doped-Li3V2(PO4)3 as A High Rate Cathode Material for Lithium-Ion Batteries. J. Mater. Chem. 2012, 22, 6556. 30. Zou, Z. Hydrothermal Synthesis and Electrochemical Performance of Al-doped VO2(B) as Cathode Materials for Lithium-Ion Battery. Int. J. Electrochem. Sci. 2017, 4979-4989. 31. Jo, J. H; Sun, Y-K; Myung, S-T; Hollandite-type Al-doped VO1.52(OH)0.77 as A Znc Ion Insertion Host Material. J. Mater. Chem. A. 2017, 5, 8367. 32. Jia, G.; Liu, S.; Yang, G.; Li, F.; Wu, K.; He, Z.; Shangguan, X. The Multiple 16


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Effects of Al-Doping on The Structure and Electrochemical Performance of LiNi0.5Mn0.5O2 as Cathode Material at High Voltage. Ionics. 2018, 24, 3705-3715. 33. Trocoli, R.; La Mantia, F. An Aqueous Zinc-Ion Battery Based on Copper Hexacyanoferrate. ChemSusChem. 2015, 8, 481-485. 34. Zhang, L.; Chen, L.; Zhou, X.; Liu, Z. Towards High-Voltage Aqueous Metal-Ion Batteries Beyond 1.5 V: The Zinc/Zinc Hexacyanoferrate System. Adv. Energy Mater. 2015, 5, 1400930. 35. Lee, J.; Ju, J. B.; Cho, W. I.; Cho, B. W.; Oh, S. H. Todorokite-Type MnO2 as A Zinc-Ion Intercalating Material. Electrochim. Acta. 2013, 112, 138-143. 36. Yang, G.; Wei, T.; Wang, C. Self-Healing Lamellar Structure Boosts Highly Stable Zinc-Storage Property of Bilayered Vanadium Oxides. ACS Appl. Mater. Interfaces. 2018, 10, 35079-35089. 37. Wei, T.; Li, Q.; Yang, G.; Wang, C. High-Rate And Durable Aqueous Zinc Ion Battery Using Dendritic V10O24·12H2O Cathode Material with Large Interlamellar Spacing. Electrochim. Acta. 2018, 287, 60-67. 38. Alfaruqi, M. H.; Mathew, V.; Song, J.; Kim, S.; Islam, S.; Pham, D. T.; Jo, J.; Kim, S.; Baboo, J. P.; Xiu, Z.; Lee, K.-S.; Sun, Y.-K.; Kim, J. Electrochemical Zinc Intercalation in Lithium Vanadium Oxide: A High-Capacity Zinc-Ion Battery Cathode. Chem. Mater. 2017, 29, 1684-1694. 39. Xu, Q; Li, J-Y; Yin, Y-X; Wan, L-J; Guo, Y-G, Watermelon-Inspired Si/C Microspheres with Hierarchical Buffer Structures for Densely Compacted Lithium-Ion Battery Anodes, Adv. Mater. 2017, 7, 1601481.

Supporting Information The Supporting Information is available free of charge on the ACS Publications website,

including

the

Experimental

section,

TEM,

characterization, and electrochemical tests data.

Competing Interests The authors declare no competing financial interest. 17


SEM,

spectroscopic


Acknowledgment This work is supported by the National Natural Science Foundation of China (U1801255, 51602354, 51872340).

18


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Figure caption Figure 1. a) XRD patterns of pure V10O24 and Al-doped V10O24. SEM images of b) pure V10O24 and c) Al-doped V10O24, d) TEM image, e) elemental mapping images, f) EDX spectra, and g) XPS spectra at Al 2p region of Al-doped V10O24. Figure 2. CV curves collected at 0.1 mV s-1 for the initial three cycles of a) V10O24 and d) Al-doped V10O24. Charge/discharge profiles at 200 mA g-1 for the initial three cycles of b) pure V10O24 and e) Al-doped V10O24. Rate performance of c) pure V10O24 and f) pure V10O24. g) Long-term cycle performances of the two materials at 5 A g-1. Figure 3. TEM and elemental mapping images of V10O24 recorded of a), b) discharged to 0.3 V, and c), d) charged to 1.6 V, respectively, and the red box shows the selected area. TEM, STEM, and elemental mapping images of Al-doped V10O24 e), f), g) discharged to 0.3 V and h), i), j) charged to 1.6 V. Figure 4. a) ex-XRD patterns of the electrodes recorded at different stages in the first two cycles collected at 30mA g-1. XPS spectra of V10O24 at pristine, fully discharged, fully charged states: b) V 2p regions and c) O 1s regions. d) The XRD patterns of pure V10O24 and Al-doped V10O24 electrodes obtained at fully charged state after long-term cycle for 21 days (collected at 100mA g-1 after 140 cycles). The inserted bar graph provides the comparison of capacity retention at different currents.

19



d

Figure 1 20 ACS Paragon Plus Environment

Page 20 of 24

Page 21 of 24

0.9

1.2

1.5

2+

Voltage (V vs. Zn /Zn)

st

1 cycle nd 2 cycle rd 3 cycle

0.3

Capacity (mAh g 

g

0.6

0.9

1.2

2+


1.5

100

200

400

1.2 0.9 0.6

st


0.3 0

100

200

300



Capacity (mAh g 

400

V10O24-Al

1.8

300

1000

1.2 0.9 0.6

st


0.3 0

100

200

300



Capacity (mAh g 

400

60

2000 5000

40

-1

Unit: mA g

20

Discharge Charge 0

20

V10O24 40

60

0

80

Cycle number

500 100 200

400

1.5

1000

200 100

80

500 2000

0

f

200

500



Capacity (mAh g 

1.5

e 2+

V10O24-Al

500

200

500

500

1000



0.6

c

Capacity (mAh g 

0.3

V10O24

2000

300

2000 5000

200

60 -1

Unit: mA g

40

100 0

80

1000

20

Discharge Charge 0

20

V10O24-Al 40

60

Cycle number

80

0

Capacity retention: 98% V10O24-Al V10O24 0

Capacity retention: 64% 500

1000

1500

Cycle number


2000

2500

3000

Coulombic efficiency (%)

Current (mA)

1.8


st


d



b 2+

Current (mA)

V10O24


a

Coulombic efficiency (%)

1 2 3 40.2 5 60.1 7 0.0 8 9 -0.1 10 11 -0.2 12 13 14 15 0.2 16 0.1 17 18 0.0 19 20 -0.1 21 22 -0.2 23 24 25 26 300 27 28 29 30 250 31 32 33 200 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



a

b

c

500 nm

h

500 nm

d

V

V

O

O

100 nm

e

Page 22 of 24

500 nm Zn

Zn

g

f

V

O

Al

Zn

V

O

Al

Zn

500 nm

i

j

500 nm


528

V

524

520

Intensity (a.u.)

1.1V 0.9V

400

0.3V 0.5V 0.7V 0.9V 1.1V 1.3V initial

10

20

30

40

2 (degree)

50

520

Full charge

d

V 2p3/2

520

Binding energy (eV)

532

2



OH

H2O

534

516

0

528

O

532

530

528

Binding energy (eV)

2

O

O 1s

536



H2O 534

OH

532

530

528

Binding energy (eV)

Capacity retention (denoted as CR)

V10O24-Al V10O24

1

100 50 0

1

1A g : 300 cycles 89% 74%

1

V10O24-Al

2

V10O24

100

5A g : 3000 cycles 98% 64%

50 0

1

V10O24-Al

0 60

530

Binding energy (eV)

Full charge

5+

V

V

524

O 1s

536

4+

V 2p1/2

528

516

Binding energy (eV)

Intensity (a.u.)

0.7V 0.5V

V

524

534

CR (%)

1.5V 1.3V

528



OH

H2O

Full discharge

5+

V 2p3/2 V

V 2p1/2

2

O

O 1s

536

4+

Intensity (a.u.)

1.6V

516

Binding energy (eV)

Full discharge

800

Intensity (a.u.)

1200

4+

V 2p1/2

Pristine

Intensity (a.u.)

(006)

c

V 2p3/2 V5+

Intensity (a.u.)

(004)

Pristine

Intensity (a.u.)

(002)

b

Intensity (a.u.)

a

Specific capacity mAh g-1

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


CR (%)

Page 23 of 24

1

Voltage (V)

10


20

2 (degree)

30

2

V10O24


TOC Graphic

24


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Boosting the Cyclic Stability of Aqueous Zinc-Ion Battery Based on Al

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