A Robust Hybrid Zn-Battery with Ultralong Cycle Life

Transcription

1 A Robust Hybrid Zn-Battery with Ultralong Cycle Life Bing Li, a Junye Quan, b Adeline Loh, #a Jianwei Chai, a Ye Chen, b Chaoliang Tan, b Xiaoming Ge, a T. S. Andy Hor, a,c Zhaolin Liu, *a Hua Zhang *b and Yun Zong *a a Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis #08-03, Singapore , Republic of Singapore. zlliu@imre.a-star.edu.sg (Z.L. Liu); y-zong@imre.a-star.edu.sg (Y. Zong) b Center for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore , Republic of Singapore. hzhang@ntu.edu.sg (H. Zhang); hzhang166@yahoo.com (H. Zhang) c Department Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China # Current address: Renewable Energy Group, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Penryn Campus, Cornwall TR10 9FE, UK. Figure S1. (a) XPS survey spectrum, (b) high-resolution O 1s spectrum of NiCo 2 O 4 on NiF@C. The 3 deconvoluted peaks in O 1s spectrum are associated with the metal oxygen bond (O 1, O 2 ) and oxygen containing species (O 3 ) such as hydroxyls, chemisorbed oxygen, etc. 31 Figure S2. SEM images of the NiCo 2 O 4 nanowires grown on Ni foam without pre-coating of carbon. (a) Low magnification and (b) high magnification.

2 Figure S3. SEM images at different magnifications of the NiCo 2 O 4 NWs grown on carbon cloth (a-c), and on carbon paper (d-f). Figure S4. Photo of NiCo 2 O 4 /NiF@C electrode with PTFE coating demonstrates the resultant electrode is highly hydrophobic. Figure S5. A comparison of electrochemical performance of batteries using bare NiF, NiF@C and NiCo 2 O 4 /NiF@C as the electrodes in air.

3 Figure S6. Cyclic voltammetry of the new electrodes, NiCo 2 O 4 NWs grown (a) on carbon paper (NiCo 2 O 4 /CP) and (b) on carbon cloth (i.e. NiCo 2 O 4 /CC), were tested. Both electrodes exhibit ORR/OER activities and a redox couple in potential window of V, similar to that of NiCo 2 O 4 /NiF@C electrode. Figure S7. Polarization curves and the corresponding power density responses of a ZnAMB in the 1st (a and b) and 2nd scan (c and d), respectively. For comparison, those of a conventional ZnAB using carbon based electrode with Pt/C catalyst are also provided (e and f). To reach a power density of 26 mw cm -2, the voltage of Pt/C-based ZnAB will drop to 1.13 V.

4 Figure S8. Morphological evolution of NiCo 2 O 4 NWs. (a) SEM image of as prepared NiCo 2 O 4 NWs. (b) SEM image of the NiCo 2 O 4 NWs at charged state after the stabilization cycling. (c) SEM image of the NiCo 2 O 4 NWs at discharged states after the stabilization cycling. Scale bars (a-c): 200 nm. (d) Schematic illustration morphological evolution of the NiCo 2 O 4 NWs at different states. Figure S9. A comparison of XPS spectra of Co 2P, Ni 2P and O 1s for the NiCo 2 O 4 /NiF@C electrodes at different states, i.e. as prepared NiCo 2 O 4 /NiF@C, discharged state (DS) and charged state (CS), respectively. The atomic ratios of Co/Ni/O (with Co as the reference) are: 1:0.86:7.43, 1:0.50:26.3 and 1:0.15:15.46 for the as prepared NiCo 2 O 4 /NiF@C and the electrode at DS and CS, respectively.

5 Robustness tests of the hybrid ZnAMB We also assessed the robustness of the hybrid battery by performing a series of tests under various conditions. The details are given in Figure S The cell was constructed as illustrated in Fig. 2a with an active electrode area of 4 cm 2. All the tests were done using a battery tester (NEWARE, Shenzhen, China). The current is restricted by the tester, which has a testable range of 1-10 ma. Figure S10. (Table) The main parameters for the test 1. (Figure) Corresponding overall voltage profile. # DIS = discharge; CHG = charge.

6 Figure S11. (Table) The main parameters for the test 2. (a) The corresponding overall voltage profile and (b,c) the details of the selected periods.

7 Figure S12. (Table) The main parameters for the test 3. (a) The corresponding overall voltage profile and (b,c) the details of the selected periods.

8 Figure S13. (Table) The main parameters for the test 4. (a) The corresponding overall voltage profile and (b,c) the details of the selected periods.

9 Figure S14. The main parameters for the test 5 and the corresponding overall voltage profile.

10 Figure S15. (Table) The main parameters for the test 6. (a) The corresponding overall voltage profile and (b,c) the details of selected periods.

11 Figure S16. Photo of the components used for assembling of coin cell (CR2032) type hybrid ZnAMB. Zn plate, glass fiber and NiCo 2 O 4 /NiF@C were served as anode, separator and cathode, respectively. The electrolyte was adsorbed in a glass fiber mat disc. Figure S17. (a) A photo of a home-built ZnAB. (b) Full discharge voltage profile of a freshly assembled ZnAMB with NiCo 2 O 4 /NiF@C electrode. (c) a photo of the Zn anode side after full discharge. The white and cloudy substance in electrolyte is ZnO particles, formed by the decomposition of zincate (Zn(OH) 4 2- ) in its saturated solution. The specific capacity of the ZnAMB battery (as primary ZnAB) with NiCo 2 O 4 /NiF@C air-cathode is estimated to be about 688 mah g Zn -1.

12 Figure S18. (a) A photo of a ZnAB constructed using Pt/C (on carbon paper) air cathode after 150 cycles at current -2 density of 2 ma cm, showing the electrolyte turned to dark brown resulted from carbon corrosion problems in alkaline condition. (b) Photos of carbon paper before and after deposition of Pt/C catalyst with controlled loading and deposition area (method was reported elsewhere, see reference 10 and 11). (c) Photos of the extracted electrolyte from the ZnAB at different cycles. Figure S19. (a) A photo of side view of a ZnAMB with NiCo2O4/NiF@C electrode after cycling tests (> 1000 cycles). The battery has been cycled extensively; this is evident from the big dendritic zinc formed as indicated by the green arrow. The electrolyte remained clear, indicating the electrode is highly stable and robust in alkaline condition. (b) A photo of extracted electrolytes from a ZnAMB with NiCo2O4/NiF@C cathode at different cycles.

13 Figure S20. Raman spectra of defects induced D-band and graphitic G-band in (black), Vulcan carbon (blue), carbon paper (red) and carbon cloth (green), respectively. The spikes in the spectra are cosmic rays generated by high energy particles from outer space. The I D /I G ratios are essentially all comparable, which generally excludes the carbon difference as a reason of notably mitigated carbon corrosion in NiCo 2 O 4 /NiF@C electrode.

14 Figure S21. Linear fitted curves for the capacity fading corresponding to the rate performance cycled at current densities of (a) 0.25, (b) 0.5, (c) 1.0 and (d) 2.0 ma cm -2 in Figure 4e, respectively. showing the capacity fading rate of the ZnMB are between 3-14 µah cm -2 per cycle, much faster than 5.3 nah cm -2 per cycle that of in the hybrid battery.

15 Figure S22. Voltage profile (a) and corresponding capacity retention plot (b) of a ZnAMB cycled at 8 ma with sufficient (cycles of 1-4 and 24-28) or insufficient chargings (cycles of 5-24). As the battery charging was switched from sufficient (cycles 1 to 4) to insufficient (cycle 5-24), the capacity of ZnM segment abruptly drops from 2.02 to 1.54 mah, and further to 1.34 mah after another 20 cycles of insufficient charging. Once the battery was reprovided with sufficient charging (from cycle 25), the capacity was found fully recovered. Figure S23. (Black) Box Plot of the NiCo 2 O 4 loading on NiCo 2 O 4 /NiF@C electrode. (Green) Box Plot of the weight changes of blank nickel foam after the hydrothermal (metal salts of Ni(NO 3 ) 2 and Co(NO 3 ) 2 were replaced by KNO 3 ) and subsequent mild air annealing process was similar to the preparation of NiCo 2 O 4 /NiF@C electrode. These control experiments suggested that the blank nickel foam itself does not react with urea solution under the same hydrothermal temperature, and the weight changing in NiCo 2 O 4 /NiF@C electrode is the actual loading of the NiCo 2 O 4.

16 Figure S24. A comparison of electrochemical performance towards ORR of the NiCo 2 O 4 /NiF@C electrodes annealed at different temperatures from 250 to 450 C for quick screening of the optimal annealing temperature for NiCo 2 O 4. The electrodes were prepared in 1 x 1 cm 2 before electrochemical measurements. All the LSV curves were recorded in 0.1 M KOH with Pt foil as the counter electrode and Ag/AgCl as the reference electrode, respectively. The results indicate the NiCo 2 O 4 /NiF@C electrode annealed at 350 C delivered highest performance towards ORR among the samples tested. Figure S25. A comparison of electrochemical performance towards ORR of the NiCo 2 O 4 /NiF@C electrodes with (red dots) and without (blue triangles) PTFE coating. The LSV curves were recorded in 0.1 M KOH with Pt foil as the counter electrode and Ag/AgCl as the reference electrode, respectively. The results suggest no significant degradation of ORR performance of the NiCo 2 O 4 /NiF@C electrode after PTFE coating step.