# Fileset

[smll202404368-sup-0001-SuppMat_2.docx](https://mdr.nims.go.jp/filesets/b318f471-108a-4cb4-8dfc-f44f452ef04f/download)

## Creator

Qiaohui Duan, Yiyi Zheng, Yu Zhou, Shuyu Dong, Calvin Ku, Patrick H.‐L. Sit, [Denis Y. W. Yu](https://orcid.org/0000-0002-5883-7087)

## Rights

[Creative Commons BY Attribution 4.0 International](https://creativecommons.org/licenses/by/4.0/)

## Other metadata

[Suppressing Formation of Zn─Mn─O Phases by In Situ Ti Decoration of MnO<sub>2</sub> for Long Lifespan MnO<sub>2</sub>‐Zn Battery](https://mdr.nims.go.jp/datasets/5c5d7114-880f-439c-9239-bfbb416ef2ea)

## Fulltext

Suppressing Formation of Zn-Mn-O Phases by In-Situ Ti Decoration of MnO2 for Long Lifespan MnO2-Zn Battery Qiaohui Duana, Yiyi Zhenga, Yu Zhoua, Shuyu Donga, Calvin Kua, Patrick H.-L. Sita, Denis Y. W. Yu b*a School of Energy and Environment, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong S.A.R.b Research Center for Energy and Environmental Materials (GREEN), National Institute for Materials Science, Tsukuba, Ibaraki, Japan* Corresponding authorEmail: yu.denis@nims.go.jpAddress: Namiki 1-1, Tsukuba, Ibaraki-ken, Japan 305-0044Figure S1. The ball-milled commercial EMD nano particles used as active material: (a) SEM image, (b) TEM image, (c) BET surface area, (d) XRD pattern, (e) crystal structure, (f) SEM EDX spectrum.Figure S2. (a) In-situ XRD profiles and (b) selected XRD patterns of EMD in Figure 1a. Note S1. The average mass loading of EMD is 1.5 mg cm-2, and the electrode disc with 16 mm diameter has an area of 2 cm-2. Since the molecular weight of MnO2 is 87 g mol-1, the total number of moles of Mn in the cathode is:The increased amount of dissolved Mn2+ in the 0.2 ml electrolyte after 1st discharge is:The percentage of Mn dissolved from the EMD active material after 1st discharge = 0.006/0.0345 = 17.4%.Since Mn dissolution is a 2e- transfer reaction with a total capacity of 616 mAh g-1, therefore, the contributed capacity from Mn dissolution isAs the total 1st discharge capacity is 250 mAh g-1, about 107.2 mAh g-1/250 mAh g-1 = 42.8% of the initial discharge capacity is contributed by Mn dissolution.  Figure S3. The 1st cycle voltage profiles of the coin cell (electrolyte amount: 200 ml) and beaker cell (electrolyte amount: 5 ml) using (a) 1M ZnSO4 electrolyte and (b) 1M ZnSO4 + 0.1M MnSO4 electrolyte; (c) their Coulombic efficiency comparison. Figure S4. XPS full spectra of EMD electrodeposited in (a) 1Zn+0.4Mn electrolyte, (b) 1Zn+0.4Mn+0.5Ti electrolyte, and (c) commercial EMD. Table S1. Atomic percentage of each element in the electrodeposited EMD on CNT electrode after charging in different electrolytes.  Element Atomic % (deposited in 1Zn+0.4Mn electrolyte) Atomic % (deposited in 1Zn+0.4Mn+0.5Ti electrolyte) O 73 65 Mn 22 32 Zn 5 <1 Ti <1 3 S <1 <1Figure S5. (a) Raman and (b) XRD patterns of the EMD electrodeposited in 1Zn+0.4Mn+0.5Ti electrolyte comparing with the two most common TiO2 phases (anatase TiO2 and rutile TiO2).  Table S2. Atomic percentage of each element in the electrodeposited EMD in 1Zn+0.4Mn+0.5Ti electrolyte before and after immersing in 0.5M NaSO4 overnight for ion exchange. Element 1Zn+0.4Mn+0.5Ti 1Zn+0.4Mn+0.5TiAfter 0.5M NaSO4 immersion O 65 71 Mn 32 25 Ti 3 4 Na <1 <1Figure S6. Illustration of Ti decoration in the EMD structure.Figure S7. The voltage profiles of the electrodeposition tests with charge capacity limit of (a) 0.2 mAh cm-2 and (b) 1.0 mAh cm-2; (c) comparison of the Coulombic efficiency of the electrodeposition tests with different capacity limits. Figure S8. Cycle performances of the CNT-Zn cells with electrolyte of (a) 1Zn+0.4Mn, (b) 1Zn+0.4Mn+0.5Ti with a fixed areal charge capacity of 0.5 mAh cm-2 and discharge current of 0.05 mA cm-2. Table S3. Ionic conductivity and pH of the electrolytes. Electrolyte Ionic conductivity (mS cm-1) pH 1Zn 25.2 4.71 1Zn+0.1Mn 28.0 4.64 1Zn+0.1Mn+0.5Ti 28.7 2.03Figure S9. Cycle stability comparison of the 1Zn+0.1Mn, 1Zn+0.1Mn+0.5Ti, and 1Zn+0.1Mn with the pH adjusted to 2.10 (close to pH of 1Zn+0.1Mn+0.5Ti) with H2SO4.Figure S10. Charge-discharge profiles of KB cathode without EMD at a low current of 0.3 mA.Table S4. Cycle performance comparison with the recent literatures. Design Current rate (A g-1) Capacity after cycles (mAh g -1) Cycle number Reference Cu-MnO2 3 151 1000 [1] IER membrane 1 215 300 [2]  5 75 900  C@PODA/MnO2 0.5 192 600 [3]  2 137 2000  Rescue of dead MnO2 1 177 600 [4] K0.27MnO2·0.54H2O 3 84 1000 [5] H+/NH4+ co-insertion 4 115 4000 [6] Co-Mn3O4 2 103 1100 [7] MnO2/KB 5 90 3000 [8] Ca-MnO2 3.5 101 5000 [9] Bi2O3/MnO2 1 190 1000 [10] MnO2@AEPA 0.5 223 200 [11]  1 142 1700  defect rich b-MnO2 1 171 800 [12] Increase top voltage cut-off 0.1 305 300 [13]  1 100 6000   Ce(SO4)2 additive 1 130 1000 [14] K+-intercalated δ-MnO2 3 190 1000 [15] TiOSO4 additive 1.5 230 1500 this work  4.8 92 10000 Figure S11. Cycle performance of the cells with different electrolytes at a low current density of 300 mA g-1.Figure S12. (a) XRD profile of ZnMn2O4; (b) cycle performance of ZnMn2O4 electrode in 1Zn electrolyte and (c) the corresponding voltage profiles.Figure S13. Comparison of cycle performance of the EMD electrode in electrolytes with different amount of TiOSO4 additive with 0.1M Mn2+ added.Figure S14. Comparison of cycle performance of the pre-doped EMD and the in-situ Ti-decorated EMD without Mn2+ addition.Figure S15. Cycle performances of the other MnO2 polymorphs using TiOSO4 electrolyte additive: (a) b-MnO2, (b) d-MnO2, (c)γ-MnO2 (synthesized).References[1] J. Zhang, W. Li, J. Wang, X. Pu, G. Zhang, S. Wang, N. Wang, X. Li, Engineering p-Band Center of Oxygen Boosting H+ Intercalation in δ-MnO2 for Aqueous Zinc Ion Batteries, Angewandte Chemie International Edition 62 (2023) e202215654.[2] Y. Wu, J. Zhi, M. Han, Z. Liu, Q. Shi, Y. Liu, P. Chen, Regulating proton distribution by ion exchange resin to achieve long lifespan aqueous Zn-MnO2 battery, Energy Storage Materials 51 (2022) 599–609.[3] Y. Zhao, R. Zhou, Z. Song, X. Zhang, T. Zhang, A. Zhou, F. Wu, R. Chen, L. Li, Interfacial Designing of MnO2 Half-Wrapped by Aromatic Polymers for High-Performance Aqueous Zinc-Ion Batteries, Angewandte Chemie International Edition 61 (2022) e202212231.[4] H. Yang, W. Zhou, D. Chen, J. Liu, Z. Yuan, M. Lu, L. Shen, V. Shulga, W. Han, D. Chao, The origin of capacity fluctuation and rescue of dead Mn-based Zn–ion batteries: a Mn-based competitive capacity evolution protocol, Energy & Environmental Science 15 (2022) 1106–1118.[5] L. Liu, Y.-C. Wu, L. Huang, K. Liu, B. Duployer, P. Rozier, P.-L. Taberna, P. Simon, Alkali ions pre-intercalated layered MnO2 nanosheet for zinc-ions storage, Advanced Energy Materials 11 (2021) 2101287.[6] S. Wang, Z. Yuan, X. Zhang, S. Bi, Z. Zhou, J. Tian, Q. Zhang, Z. Niu, Non-metal ion co-insertion chemistry in aqueous Zn/MnO2 batteries, Angewandte Chemie 133 (2021) 7132–7136.[7] J. Ji, H. Wan, B. Zhang, C. Wang, Y. Gan, Q. Tan, N. Wang, J. Yao, Z. Zheng, P. Liang, J. Zhang, H. Wang, L. Tao, Y. Wang, D. Chao, H. Wang, Co2+/3+/4+-regulated electron state of Mn-O for superb aqueous zinc-manganese oxide batteries, Advanced Energy Materials 11 (2021) 2003203.[8] X. Yang, Z. Jia, W. Wu, H.-Y. Shi, Z. Lin, C. Li, X.-X. Liu, X. Sun, The back-deposition of dissolved Mn2+ to MnO2 cathodes for stable cycling in aqueous zinc batteries, Chemical Communications 58 (2022) 4845–4848.[9] T. Sun, Q. Nian, S. Zheng, J. Shi, Z. Tao, Layered Ca0. 28MnO2· 0.5 H2O as a high performance cathode for aqueous zinc-ion battery, Small 16 (2020) 2000597.[10] Q. Duan, Y. Wang, S. Dong, D. Y. W. Yu, Facile electrode additive stabilizes structure of electrolytic MnO2 for mild aqueous rechargeable zinc-ion battery, Journal of Power Sources 528 (2022) 231194.[11] X. Xiao, L. Zhang, W. Xin, M. Yang, Y. Geng, M. Niu, H. Zhang, Z. Zhu, Self-Assembled Layer of Organic Phosphonic Acid Enables Highly Stable MnO2 Cathode for Aqueous Znic Batteries, Small (2024) 2309271.[12] J. Zheng, C. Qin, C. Chen, C. Zhang, P. Shi, X. Chen, Y. Gan, J. Li, J. Yao, X. Liu, J. Cheng, D. Sun, H. Wan, H. Wang, Ostwald ripening mechanism-derived MnOOH induces lattice oxygen escape for efficient aqueous MnO2–Zn batteries, Journal of Materials Chemistry A 11 (2023) 24311–24320.[13] Y. Liu, Z. Qin, X. Yang, J. Liu, X.-X. Liu, X. Sun, Voltage induced lattice contraction enabling superior cycling stability of MnO2 cathode in aqueous zinc batteries, Energy Storage Materials 56 (2023) 524–531.[14] G. Lai, P. Ruan, X. Hu, B. Lu, S. Liang, Y. Tang, J. Zhou, Dynamic compensation of MnOOH to mitigate the irregular dissolution of MnO2 in rechargeable aqueous Zn/MnO2 batteries, Journal of Materials Chemistry A 11 (2023) 15211–15218.[15] J. Yang, G. Yao, Z. Li, Y. Zhang, L. Wei, H. Niu, Q. Chen, F. Zheng, Highly Flexible K-Intercalated MnO2/Carbon Membrane for High-Performance Aqueous Zinc-Ion Battery Cathode, Small 19 (2023) 2205544.image5.pngimage6.pngimage7.pngimage8.pngimage9.emf0 500 1000 15000100200300Discharge capacity (mAh g-1)Cycle number 1Zn+0.1Mn (pH=4.64) 1Zn+0.1Mn+0.5Ti (pH=2.03) 1Zn+0.1Mn (pH=2.10 with diluted H2SO4)1200 mA g-1image10.emf0.000 0.001 0.002 0.003 0.004 0.0050.61.01.41.8Voltage (V)Capacity (mAh) 1st cycle 2nd cycle 3rd cycle 4th cycleKB//1Zn+0.1Mn+0.5Ti//Zn                             0.3 mAcapacity < 0.0005 mAhbarely no capacity contributed by electrolyteimage11.emf0 100 200 300 40050150250350Discharge capacity (mAh g-1)Cycle number 1Zn 1Zn+0.1Mn 1Zn+0.1Mn+0.5Ti300 mA g-1image12.pngimage13.emf0 50 100 150 200050100150200250300350Discharge capacity (mAh g-1)Cycle number 1Zn+0.1Mn +0.2Ti       +2Ti +0.5Ti       +5Ti900 mA g-1image14.emf0 20 40 60 80 10050150250350Discharge capacity (mAh g-1)Cycle number pre Ti-doped EMD (1Zn) in-situ Ti-decorated EMD (1Zn+0.5Ti)300 mA g-1image15.pngimage1.pngimage2.pngimage3.pngimage4.png