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Volume 28 Issue 10
Oct.  2021

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Tao Wei, Zao-hong Zhang, Qi Zhang, Jia-hao Lu, Qi-ming Xiong, Feng-yue Wang, Xin-ping Zhou, Wen-jia Zhao,  and Xiang-yun Qiu, Anion-immobilized solid composite electrolytes based on metal-organic frameworks and superacid ZrO2 fillers for high-performance all solid-state lithium metal batteries, Int. J. Miner. Metall. Mater., 28(2021), No. 10, pp. 1636-1646. https://doi.org/10.1007/s12613-021-2289-z
Cite this article as:
Tao Wei, Zao-hong Zhang, Qi Zhang, Jia-hao Lu, Qi-ming Xiong, Feng-yue Wang, Xin-ping Zhou, Wen-jia Zhao,  and Xiang-yun Qiu, Anion-immobilized solid composite electrolytes based on metal-organic frameworks and superacid ZrO2 fillers for high-performance all solid-state lithium metal batteries, Int. J. Miner. Metall. Mater., 28(2021), No. 10, pp. 1636-1646. https://doi.org/10.1007/s12613-021-2289-z
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研究论文

一种利用具备阴离子固定作用的MOF以及酸性ZrO2改性的全固态锂离子电池复合电解质

  • Research Article

    Anion-immobilized solid composite electrolytes based on metal-organic frameworks and superacid ZrO2 fillers for high-performance all solid-state lithium metal batteries

    + Author Affiliations
    • Anion-immobilized solid composite electrolytes (SCEs) are important to restrain the propagation of lithium dendrites for all solid-state lithium metal batteries (ASSLMBs). Herein, a novel SCEs based on metal-organic frameworks (MOFs, UiO-66-NH2) and superacid ZrO2 (S-ZrO2) fillers are proposed, and the samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), thermo-gravimetric analyzer (TGA) and some other electrochemical measurements. The –NH2 groups of UiO-66-NH2 combines with F atoms of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) chains by hydrogen bonds, leading to a high electrochemical stability window of 5 V. Owing to the incorporation of UiO-66-NH2 and S-ZrO2 in PVDF-HFP polymer, the open metal sites of MOFs and acid surfaces of S-ZrO2 can immobilize anions by strong Lewis acid-base interaction, which enhances the effect of immobilization anions, achieving a high Li-ion transference number (t+) of 0.72, and acquiring a high ionic conductivity of 1.05×10–4 S·cm–1 at 60°C. The symmetrical Li/Li cells with the anion-immobilized SCEs may steadily operate for over 600 h at 0.05 mA·cm–2 without the short-circuit occurring. Besides, the solid composite Li/LiFePO4 (LFP) cell with the anion-immobilized SCEs shows a superior discharge specific capacity of 158 mAh·g–1 at 0.2 C. The results illustrate that the anion-immobilized SCEs are one of the most promising choices to optimize the performances of ASSLMBs.

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    • [1]
      Z.M. Zheng, H.H. Wu, H.D. Liu, Q.B. Zhang, X. He, S.C. Yu, V. Petrova, J. Feng, R. Kostecki, P. Liu, D.L. Peng, M.L. Liu, and M.S. Wang, Achieving fast and durable lithium storage through amorphous FeP nanoparticles encapsulated in ultrathin 3D P-doped porous carbon nanosheets, ACS Nano, 14(2020), No. 8, p. 9545. doi: 10.1021/acsnano.9b08575
      [2]
      J.M. Jiang, G.D. Nie, P. Nie, Z.W. Li, Z.H. Pan, Z.K. Kou, H. Dou, X.G. Zhang, and J. Wang, Nanohollow carbon for rechargeable batteries: Ongoing progresses and challenges, Nano Micro Lett., 12(2020), No. 1, p. 1. doi: 10.1007/s40820-019-0337-2
      [3]
      Z.M. Zheng, P. Li, J. Huang, H.D. Liu, Y. Zao, Z.L. Hu, L. Zhang, H.X. Chen, M.S. Wang, D.L. Peng, and Q.B. Zhang, High performance columnar-like Fe2O3@carbon composite anode via yolk@shell structural design, J. Energy Chem., 41(2020), p. 126. doi: 10.1016/j.jechem.2019.05.009
      [4]
      Y.Q. Su, X.Y. Zhang, L.M. Liu, Y.T. Zhao, F. Liu, and Q.S. Huang, Optimization of battery life and capacity by setting dense mesopores on the surface of nanosheets used as electrode, Int. J. Miner. Metall. Mater., 28(2021), No. 1, p. 142. doi: 10.1007/s12613-020-2088-y
      [5]
      Q.B. Zhang, H.X. Chen, L.L. Luo, B.T. Zhao, H. Luo, X. Han, J.W. Wang, C.M. Wang, Y. Yang, T. Zhu, and M.L. Liu, Harnessing the concurrent reaction dynamics in active Si and Ge to achieve high performance lithium-ion batteries, Energy Environ. Sci., 11(2018), No. 3, p. 669. doi: 10.1039/C8EE00239H
      [6]
      W.X. Zhao, L.X. Gao, L.C. Yue, X.Y. Wang, Q. Liu, Y.L. Luo, T.S. Li, X.F. Shi, A.M. Asiri, and X.P. Sun, Constructing a hollow microflower-like ZnS/CuS@C heterojunction as an effective ion-transport booster for an ultrastable and high-rate sodium storage anode, J. Mater. Chem. A, 9(2021), No. 10, p. 6402. doi: 10.1039/D1TA00497B
      [7]
      Y.M. Wu, H.T. Zhao, Z.G. Wu, L.C. Yue, J. Liang, Q. Liu, Y.L. Luo, S.Y. Gao, S.Y. Lu, G. Chen, X.F. Shi, B.H. Zhong, X.D. Guo, and X.P. Sun, Rational design of carbon materials as anodes for potassium-ion batteries, Energy Storage Mater., 34(2021), p. 483. doi: 10.1016/j.ensm.2020.10.015
      [8]
      L.C. Yue, H.T. Zhao, Z.G. Wu, J. Liang, S.Y. Lu, G. Chen, S.Y. Gao, B.H. Zhong, X.D. Guo, and X.P. Sun, Recent advances in electrospun one-dimensional carbon nanofiber structures/heterostructures as anode materials for sodium ion batteries, J. Mater. Chem. A, 8(2020), No. 23, p. 11493. doi: 10.1039/D0TA03963B
      [9]
      L. Chen, Y.T. Li, S.P. Li, L.Z. Fan, C.W. Nan, and J.B. Goodenough, PEO/garnet composite electrolytes for solid-state lithium batteries: From "ceramic-in-polymer" to "polymer-in-ceramic", Nano Energy, 46(2018), p. 176. doi: 10.1016/j.nanoen.2017.12.037
      [10]
      Q.B. Zhang, Z.L. Gong, and Y. Yang, Advance in interface and characterizations of sulfide solid electrolyte materials, Acta Phys. Sinica, 69(2020), No. 22, art. No. 228803. doi: 10.7498/aps.69.20201581
      [11]
      Z.Y. Huang, W.Y. Pang, P. Liang, Z.H. Jin, N. Grundish, Y.T. Li, and C.A. Wang, A dopamine modified Li6.4La3Zr1.4Ta0.6O12/PEO solid-state electrolyte: Enhanced thermal and electrochemical properties, J. Mater. Chem. A, 7(2019), No. 27, p. 16425. doi: 10.1039/C9TA03395E
      [12]
      Z.H. Zhang, T. Wei, J.H. Lu, Q.M. Xiong, Y.H. Ji, Z.Y. Zhu, and L.T. Zhang, Practical development and challenges of garnet-structured Li7La3Zr2O12 electrolytes for all solid-state lithium-ion battery-a review, Int. J. Miner. Metall. Mater., 28(2021), 10, p. 1565. doi: 10.1007/s12613-020-2239-1
      [13]
      K. Jeong, S. Park, and S.Y. Lee, Revisiting polymeric single lithium-ion conductors as an organic route for all-solid-state lithium ion and metal batteries, J. Mater. Chem. A, 7(2019), No. 5, p. 1917. doi: 10.1039/C8TA09056D
      [14]
      D.C. Lin, Y.Y. Liu, Z. Liang, H.W. Lee, J. Sun, H.T. Wang, K. Yan, J. Xie, and Y. Cui, Layered reduced graphene oxide with nanoscale interlayer gaps as a stable host for lithium metal anodes, Nat. Nanotechnol., 11(2016), No. 7, p. 626. doi: 10.1038/nnano.2016.32
      [15]
      H. Zhang, C.M. Li, M. Piszcz, E. Coya, T. Rojo, L.M. Rodriguez-Martinez, M. Armand, and Z.B. Zhou, Single lithium-ion conducting solid polymer electrolytes: Advances and perspectives, Chem. Soc. Rev., 46(2017), No. 3, p. 797. doi: 10.1039/C6CS00491A
      [16]
      C.P. Yang, L. Zhang, B.Y. Liu, S.M. Xu, T. Hamann, D. McOwen, J.Q. Dai, W. Luo, Y.H. Gong, E.D. Wachsman, and L.B. Hu, Continuous plating/stripping behavior of solid-state lithium metal anode in a 3D ion-conductive framework, Proc. Natl. Acad. Sci. U.S.A., 115(2018), No. 15, p. 3770. doi: 10.1073/pnas.1719758115
      [17]
      Q.Q. Zhang, K. Liu, F. Ding, and X.J. Liu, Recent advances in solid polymer electrolytes for lithium batteries, Nano Res., 10(2017), No. 12, p. 4139. doi: 10.1007/s12274-017-1763-4
      [18]
      C.W. Sun, J. Liu, Y.D. Gong, D.P. Wilkinson, and J.J. Zhang, Recent advances in all-solid-state rechargeable lithium batteries, Nano Energy, 33(2017), p. 363. doi: 10.1016/j.nanoen.2017.01.028
      [19]
      M. Shoji, E.J. Cheng, T. Kimura, and K. Kanamura, Recent progress for all solid state battery using sulfide and oxide solid electrolytes, J. Phys. D: Appl. Phys., 52(2019), No. 10, art. No. 103001. doi: 10.1088/1361-6463/aaf7e2
      [20]
      F.D. Han, Y.Z. Zhu, X.F. He, Y.F. Mo, and C.S. Wang, Electrochemical stability of Li10GeP2S12 and Li7La3Zr2O12 solid electrolytes, Adv. Energy Mater., 6(2016), No. 8, art. No. 1501590. doi: 10.1002/aenm.201501590
      [21]
      Y. Wang and W.H. Zhong, Development of electrolytes towards achieving safe and high-performance energy-storage devices: A review, ChemElectroChem, 2(2015), No. 1, p. 3. doi: 10.1002/celc.201402416
      [22]
      A.I. Pitillas Martinez, F. Aguesse, L. Otaegui, M. Schneider, A. Roters, A. Llordés, and L. Buannic, The cathode composition, a key player in the success of Li-metal solid-state batteries, J. Phys. Chem. C, 123(2019), No. 6, p. 3270. doi: 10.1021/acs.jpcc.8b04626
      [23]
      J. Zheng and Y.Y. Hu, New insights into the compositional dependence of Li-ion transport in polymer-ceramic composite electrolytes, ACS Appl. Mater. Interfaces, 10(2018), No. 4, p. 4113. doi: 10.1021/acsami.7b17301
      [24]
      Z.N. Wang, S. Wang, A.L. Wang, X. Liu, J. Chen, Q.H. Zeng, L. Zhang, W. Liu, and L.Y. Zhang, Covalently linked metal-organic framework (MOF)-polymer all-solid-state electrolyte membranes for room temperature high performance lithium batteries, J. Mater. Chem. A, 6(2018), No. 35, p. 17227. doi: 10.1039/C8TA05642K
      [25]
      R. Zhao, Z.B. Liang, R.Q. Zou, and Q. Xu, Metal-organic frameworks for batteries, Joule, 2(2018), No. 11, p. 2235. doi: 10.1016/j.joule.2018.09.019
      [26]
      F.L. Zhu, H.F. Bao, X.S. Wu, Y.L. Tao, C. Qin, Z.M. Su, and Z.H. Kang, High-performance metal-organic framework-based single ion conducting solid-state electrolytes for low-temperature lithium metal batteries, ACS Appl. Mater. Interfaces, 11(2019), No. 46, p. 43206. doi: 10.1021/acsami.9b15374
      [27]
      Y.C. Jiang, H.T. Zhao, L.C. Yue, J. Liang, T.S. Li, Q. Liu, Y.L. Luo, X.Z. Kong, S.Y. Lu, X.F. Shi, K. Zhou, and X.P. Sun, Recent advances in lithium-based batteries using metal organic frameworks as electrode materials, Electrochem. Commun., 122(2021), art. No. 106881. doi: 10.1016/j.elecom.2020.106881
      [28]
      B.M. Wiers, M.L. Foo, N.P. Balsara, and J.R. Long, A solid lithium electrolyte via addition of lithium isopropoxide to a metal-organic framework with open metal sites, J. Am. Chem. Soc., 133(2011), No. 37, p. 14522. doi: 10.1021/ja205827z
      [29]
      B. Chen, Z. Huang, X.T. Chen, Y.R. Zhao, Q. Xu, P. Long, S.J. Chen, and X.X. Xu, A new composite solid electrolyte PEO/Li10GeP2S12/SN for all-solid-state lithium battery, Electrochim. Acta, 210(2016), p. 905. doi: 10.1016/j.electacta.2016.06.025
      [30]
      A.R. Polu and H.W. Rhee, Effect of TiO2 nanoparticles on structural, thermal, mechanical and ionic conductivity studies of PEO12-LiTDI solid polymer electrolyte, J. Ind. Eng. Chem., 37(2016), p. 347. doi: 10.1016/j.jiec.2016.03.042
      [31]
      L.J. Zhu, L.P. Zhu, P.B. Zhang, B.K. Zhu, and Y.Y. Xu, Surface zwitterionicalization of poly(vinylidene fluoride) membranes from the entrapped reactive core-shell silica nanoparticles, J. Colloid Interface Sci., 468(2016), p. 110. doi: 10.1016/j.jcis.2016.01.043
      [32]
      H.M.J.C. Pitawala, M.A.K.L. Dissanayake, V.A. Seneviratne, B.E. Mellander, and I. Albinson, Effect of plasticizers (EC or PC) on the ionic conductivity and thermal properties of the (PEO)9LiTf: Al2O3 nanocomposite polymer electrolyte system, J. Solid State Electrochem., 12(2008), p. 783. doi: 10.1007/s10008-008-0505-7
      [33]
      Z.Y. Tu, P. Nath, Y.Y. Lu, M.D. Tikekar, and L.A. Archer, Nanostructured electrolytes for stable lithium electrodeposition in secondary batteries, Acc. Chem. Res., 48(2015), No. 11, p. 2947. doi: 10.1021/acs.accounts.5b00427
      [34]
      F. Croce, L. Persi, B. Scrosati, F. Serraino-Fiory, E. Plichta, and M.A. Hendrickson, Role of the ceramic fillers in enhancing the transport properties of composite polymer electrolytes, Electrochim. Acta, 46(2001), No. 16, p. 2457. doi: 10.1016/S0013-4686(01)00458-3
      [35]
      F. Croce, L. Settimi, and B. Scrosati, Superacid ZrO2-added, composite polymer electrolytes with improved transport properties, Electrochem. Commun., 8(2006), No. 2, p. 364. doi: 10.1016/j.elecom.2005.12.002
      [36]
      T. Wei, Z.H. Zhang, Z.M. Wang, Q. Zhang, Y.S. Ye, J.H. Lu, Z.U. Rahman, and Z.W. Zhang, Ultrathin solid composite electrolyte based on Li6.4La3Zr1.4Ta0.6O12/PVDF-HFP/LiTFSI/succinonitrile for high-performance solid-state lithium metal batteries, ACS Appl. Energy Mater., 3(2020), No. 9, p. 9428. doi: 10.1021/acsaem.0c01872
      [37]
      M.J. Katz, Z.J. Brown, Y.J. Colón, P.W. Siu, K.A. Scheidt, R.Q. Snurr, J.T. Hupp, and O.K. Farha, A facile synthesis of UiO-66, UiO-67 and their derivatives, Chem. Commun., 49(2013), No. 82, art. No. 9449. doi: 10.1039/c3cc46105j
      [38]
      J.F. Wu and X. Guo, Nanostructured metal-organic framework (MOF)-derived solid electrolytes realizing fast lithium ion transportation kinetics in solid-state batteries, Small, 15(2019), No. 5, art. No. 1804413. doi: 10.1002/smll.201804413
      [39]
      X.Y. Xu and B. Yan, Selective detection and controlled release of Aspirin over fluorescent amino-functionalized metal-organic framework in aqueous solution, Sens. Actuators, B, 230(2016), p. 463. doi: 10.1016/j.snb.2016.02.101
      [40]
      H.Y. Huo, B. Wu, T. Zhang, X.S. Zheng, L. Ge, T.W. Xu, X.X. Guo, and X.L. Sun, Anion-immobilized polymer electrolyte achieved by cationic metal-organic framework filler for dendrite-free solid-state batteries, Energy Storage Mater., 18(2019), p. 59. doi: 10.1016/j.ensm.2019.01.007
      [41]
      X.M. Li, J. Liu, C. Zhao, J.L. Zhou, L. Zhao, S.L. Li, and Y.Q. Lan, Strategic hierarchical improvement of superprotonic conductivity in a stable metal-organic framework system, J. Mater. Chem. A, 7(2019), No. 43, p. 25165. doi: 10.1039/C9TA10286H
      [42]
      C.F. Yuan, J. Li, P.F. Han, Y.Q. Lai, Z.A. Zhang, and J. Liu, Enhanced electrochemical performance of poly(ethylene oxide) based composite polymer electrolyte by incorporation of nano-sized metal-organic framework, J. Power Sources, 240(2013), p. 653. doi: 10.1016/j.jpowsour.2013.05.030
      [43]
      H.B. Wu and X.W.D. Lou, Metal-organic frameworks and their derived materials for electrochemical energy storage and conversion: Promises and challenges, Sci. Adv., 3(2017), No. 12, art. No. eaap9252. doi: 10.1126/sciadv.aap9252
      [44]
      Y. Zhang, J. Xiong, C. Chen, Q.Z. Li, J.J. Liu, and Z.C. Zhang, Regulating the dissociation of LiCl and transportation of Li ions within UiO-66-NH2 framework for humidity sensing applications with superb comprehensive performances, J. Alloys Compd., 818(2020), art. No. 152854. doi: 10.1016/j.jallcom.2019.152854
      [45]
      J. Lu, Y.C. Liu, P.H. Yao, Z.Y. Ding, Q.M. Tang, J.W. Wu, Z.R. Ye, K. Huang, and X.J. Liu, Hybridizing poly(vinylidene fluoride-co-hexafluoropropylene) with Li6.5La3Zr1.5Ta0.5O12 as a lithium-ion electrolyte for solid state lithium metal batteries, Chem. Eng. J., 367(2019), p. 230. doi: 10.1016/j.cej.2019.02.148
      [46]
      R. Qiao, H. Deng, K.W. Putz, and L.C. Brinson, Effect of particle agglomeration and interphase on the glass transition temperature of polymer nanocomposites, J. Polym. Sci. B: Polym. Phys., 49(2011), No. 10, p. 740. doi: 10.1002/polb.22236
      [47]
      Y. Xia, X.L. Wang, X.H. Xia, R.C. Xu, S.Z. Zhang, J.B. Wu, Y.F. Liang, C.D. Gu, and J.P. Tu, A newly designed composite gel polymer electrolyte based on poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) for enhanced solid-state lithium-sulfur batteries, Chem. Eur. J., 23(2017), No. 60, p. 15203. doi: 10.1002/chem.201703464
      [48]
      T. Huang, M.C. Long, X.L. Wang, G. Wu, and Y.Z. Wang, One-step preparation of poly(ionic liquid)-based flexible electrolytes by in situ polymerization for dendrite-free lithium ion batteries, Chem. Eng. J., 375(2019), art. No. 122062. doi: 10.1016/j.cej.2019.122062
      [49]
      H. Yang, J. Bright, B.H. Chen, P. Zheng, X.F. Gao, B.T. Liu, S. Kasani, X.W. Zhang, and N.Q. Wu, Chemical interaction and enhanced interfacial ion transport in a ceramic nanofiber-polymer composite electrolyte for all-solid-state lithium metal batteries, J. Mater. Chem. A, 8(2020), No. 15, p. 7261. doi: 10.1039/C9TA12495K
      [50]
      N. Chen, Y. Xing, L.L. Wang, F. Liu, L. Li, R.J. Chen, F. Wu, and S.J. Guo, "Tai Chi" philosophy driven rigid-flexible hybrid ionogel electrolyte for high-performance lithium battery, Nano Energy, 47(2018), p. 35. doi: 10.1016/j.nanoen.2018.02.036
      [51]
      W.Q. Zhang, J.H. Nie, F. Li, Z.L. Wang, and C.W. Sun, A durable and safe solid-state lithium battery with a hybrid electrolyte membrane, Nano Energy, 45(2018), p. 413. doi: 10.1016/j.nanoen.2018.01.028
      [52]
      Y. Li, W. Arnold, A. Thapa, J.B. Jasinski, G. Sumanasekera, M. Sunkara, T. Druffel, and H. Wang, Stable and flexible sulfide composite electrolyte for high-performance solid-state lithium batteries, ACS Appl. Mater. Interfaces, 12(2020), No. 38, p. 42653. doi: 10.1021/acsami.0c08261
      [53]
      L.N. Cong, Y.N. Li, W. Lu, J. Jie, Y.L. Liu, L.Q. Sun, and H.M. Xie, Unlocking the poly(vinylidene fluoride-co-hexafluoropropylene)/Li10GeP2S12 composite solid-state electrolytes for dendrite-free Li metal batteries assisting with perfluoropolyethers as bifunctional adjuvant, J. Power Sources, 446(2020), art. No. 227365. doi: 10.1016/j.jpowsour.2019.227365
      [54]
      P. Xu, H.Y. Chen, X. Zhou, and H.F. Xiang, Gel polymer electrolyte based on PVDF-HFP matrix composited with rGO-PEG-NH2 for high-performance lithium ion battery, J. Membr. Sci., 617(2021), art. No. 118660. doi: 10.1016/j.memsci.2020.118660
      [55]
      K.X. Huang, Y.Y. Wang, H.W. Mi, D.T. Ma, B. Yong, and P.X. Zhang, [BMIM]BF4-modified PVDF-HFP composite polymer electrolyte for high-performance solid-state lithium metal battery, J. Mater. Chem. A, 8(2020), No. 39, p. 20593. doi: 10.1039/D0TA08169H
      [56]
      J.X. Ma, C.S. Wang, and S. Wroblewski, Kinetic characteristics of mixed conductive electrodes for lithium ion batteries, J. Power Sources, 164(2007), No. 2, p. 849. doi: 10.1016/j.jpowsour.2006.11.024
      [57]
      L.Y. Wang, L.F. Wang, R. Wang, R. Xu, C. Zhan, W. Yang, and G.C. Liu, Solid electrolyte-electrode interface based on buffer therapy in solid-state lithium batteries, Int. J. Miner. Metall. Mater., 28(2021), No. 10, p. 1584. doi: 10.1007/s12613-021-2278-2
      [58]
      Y.F. Liang, S.J. Deng, Y. Xia, X.L. Wang, X.H. Xia, J.B. Wu, C.D. Gu, and J.P. Tu, A superior composite gel polymer electrolyte of Li7La3Zr2O12-poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) for rechargeable solid-state lithium ion batteries, Mater. Res. Bull., 102(2018), p. 412. doi: 10.1016/j.materresbull.2018.02.051
      [59]
      D.Y.W. Yu, C. Fietzek, W. Weydanz, K. Donoue, T. Inoue, H. Kurokawa, and S. Fujitani, Study of LiFePO4 by cyclic voltammetry, J. Electrochem. Soc., 154(2007), No. 4, p. A253. doi: 10.1149/1.2434687

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