鋰金屬被視為鋰離子二次電池陽極材料中的聖杯，因其擁有極高的理論電容量(3860 mAh/g)，以即很低的電化學還原電位(–3.04V vs. the SHE)，故開發高能量密度鋰金屬電池系統勢必成為最終目標；而另外一個亦將能量密度提升至最高的系統則是無陽極全電池，因其不需要陽極活性材料，故電池之體積可以完全用於陰極材料以增加能量密度，同時重量可以降至最低。儘管人們一直努力想要將鋰金屬電池及無陽極全電池商業化，鋰樹枝狀晶體的複雜生長機制阻礙了其廣泛應用，其中安全和短循環壽命是兩個主要問題。因此為了解決本質上的問題，了解鋰枝晶複雜的生長機制為根本之道，故我們利用了原位光學顯微鏡技術，以特殊電池設計，穩定控制電流密度，因此可以在給定之條件下研究鋰樹枝狀晶體的生長，將電池關鍵參數及不同電解液對鋰枝晶生長模式之影響進行分析及研究，其中包含多種添加劑對鋰枝晶生長機制的影響、計算鋰沉積的厚度、充電時鋰的生長形態、體積變化和放電後的孔隙率，這些皆可為介面化學提供新的啟示。

Lithium metal has been regarded as the holy grail for the anode material of lithium ion secondary battery due to its remarkably high theoretical specific capacity (3860 mAh/g) and low reduction potential (-3.04V vs. the SHE). The development of a lithium metal battery system with high energy density is bound to be the ultimate goal. Another system that can increase the energy density to the highest level is the anode-free full cell. Because the active anode material is not required, the volume of the battery can be fully dedicated to the cathodic material to increase the energy density, while the weight can be kept to the minimum. Although people have been trying to commercialize lithium metal batteries and anode-free full cell recently, the complex growth mechanism of lithium dendrites has hindered widespread deployment. Among all, safety and short cycle life are two major concerns. Therefore, understanding the growth mechanism of lithium dendrites is the key to solving these problems. We utilized in-situ optical microscopy technology. A special battery design enabled stable control of the current density so that lithium growth could be studied under given conditions. Critical operating parameters of a battery and the effects of different electrolytes, including various additives, on the growth mechanism of lithium dendrites, were analyzed. The thickness of lithium deposition, the morphology of lithium growth upon charging, volumetric change, and porosity after discharge, were estimated to shed light on the interfacial chemistry of various electrolytes.

[1] M. A. K. a. J. B. Heywood, "Electric Powertrains: Opportunities and Challenges in the U.S. Light-Duty Vehicle Fleet " 2007.
[2] K. Mizushima, P. Jones, P. Wiseman, and J. B. Goodenough, "LixCoO2 (0< x<-1): A new cathode material for batteries of high energy density," Materials Research Bulletin, vol. 15, no. 6, pp. 783-789, 1980.
[3] K. Mizushima, P. Jones, P. Wiseman, and J. B. Goodenough, "LixCoO2 (0< x⩽ 1): A new cathode material for batteries of high energy density," Solid State Ionics, vol. 3, pp. 171-174, 1981.
[4] M. Thackeray, W. David, P. Bruce, and J. B. Goodenough, "Lithium insertion into manganese spinels," Materials Research Bulletin, vol. 18, no. 4, pp. 461-472, 1983.
[5] K. Z. A. M. Christian M. Julien , and a. H. Groult, "Comparative Issues of Cathode Materials for Li-Ion Batteries," inorganics, pp. 132-154, 2014.
[6] "A Ubiquitous Power Source, Batteries Are all Around Us in Age of Digital Consumerism," Global Industry Analysts, Inc.
[7] Y. NISHI, "The Development of Lithium Ion Secondary Batteries " The Japan Chemical Journal Forum and John Wiley & Sons, Inc., 8 June 2001
[8] "About Lithium-Ion Battery Manufacturing," Chris Hillseth Enterprises.
[9] J. B. Goodenough and K.-S. Park, "The Li-ion rechargeable battery: a perspective," Journal of the American Chemical Society, vol. 135, no. 4, pp. 1167-1176, 2013.
[10] J.-M. Tarascon and M. Armand, "Issues and challenges facing rechargeable lithium batteries," in Materials for sustainable energy: a collection of peer-reviewed research and review articles from Nature Publishing Group: World Scientific, 2011, pp. 171-179.
[11] W. Xu, J. Wang, F. Ding, X. Chen, E. Nasybulin, Y. Zhang, and J.-G. Zhang, "Lithium metal anodes for rechargeable batteries," Energy & Environmental Science, vol. 7, no. 2, pp. 513-537, 2014.
[12] P. G. Bruce, S. A. Freunberger, L. J. Hardwick, and J.-M. Tarascon, "Li–O2 and Li–S batteries with high energy storage," Nature materials, vol. 11, no. 1, pp. 19-29, 2012.
[13] T. T. Hagos, W.-N. Su, C.-J. Huang, B. Thirumalraj, S.-F. Chiu, L. H. Abrha, T. M. Hagos, H. K. Bezabh, G. B. Berhe, and W. A. Tegegne, "Developing high-voltage carbonate-ether mixed electrolyte via anode-free cell configuration," Journal of Power Sources, vol. 461, p. 228053, 2020.
[14] B. A. Jote, T. T. Beyene, N. A. Sahalie, M. A. Weret, B. W. Olbassa, Z. T. Wondimkun, G. B. Berhe, C.-J. Huang, W.-N. Su, and B. J. Hwang, "Effect of diethyl carbonate solvent with fluorinated solvents as electrolyte system for anode free battery," Journal of Power Sources, vol. 461, p. 228102, 2020.
[15] F. Ding, W. Xu, G. L. Graff, J. Zhang, M. L. Sushko, X. Chen, Y. Shao, M. H. Engelhard, Z. Nie, and J. Xiao, "Dendrite-free lithium deposition via self-healing electrostatic shield mechanism," Journal of the American Chemical Society, vol. 135, no. 11, pp. 4450-4456, 2013.
[16] C. Monroe and J. Newman, "Dendrite growth in lithium/polymer systems a propagation model for liquid electrolytes under galvanostatic conditions," Journal of The Electrochemical Society, vol. 150, no. 10, pp. A1377-A1384, 2003.
[17] D. Lin, Y. Liu, and Y. Cui, "Reviving the lithium metal anode for high-energy batteries," Nature nanotechnology, vol. 12, no. 3, p. 194, 2017.
[18] J. Betz, G. Bieker, P. Meister, T. Placke, M. Winter, and R. Schmuch, "Theoretical versus practical energy: a plea for more transparency in the energy calculation of different rechargeable battery systems," Advanced Energy Materials, vol. 9, no. 6, p. 1803170, 2019.
[19] S. Nanda, A. Gupta, and A. Manthiram, "Anode-Free Full Cells: A Pathway to High-Energy Density Lithium-Metal Batteries," Advanced Energy Materials, p. 2000804, 2020.
[20] J. Heine, P. Hilbig, X. Qi, P. Niehoff, M. Winter, and P. Bieker, "Fluoroethylene carbonate as electrolyte additive in tetraethylene glycol dimethyl ether based electrolytes for application in lithium ion and lithium metal batteries," Journal of The Electrochemical Society, vol. 162, no. 6, pp. A1094-A1101, 2015.
[21] R. Weber, M. Genovese, A. Louli, S. Hames, C. Martin, I. G. Hill, and J. Dahn, "Long cycle life and dendrite-free lithium morphology in anode-free lithium pouch cells enabled by a dual-salt liquid electrolyte," Nature Energy, vol. 4, no. 8, pp. 683-689, 2019.
[22] S. Jurng, Z. L. Brown, J. Kim, and B. L. Lucht, "Effect of electrolyte on the nanostructure of the solid electrolyte interphase (SEI) and performance of lithium metal anodes," Energy & Environmental Science, vol. 11, no. 9, pp. 2600-2608, 2018.
[23] Z. Brown and B. Lucht, "Synergistic Performance of Lithium Difluoro(oxalato)borate and Fluoroethylene Carbonate in Carbonate Electrolytes for Lithium Metal Anodes," Journal of The Electrochemical Society, vol. 166, pp. A5117-A5121, 01/01 2019, doi: 10.1149/2.0181903jes.
[24] T. Schedlbauer, S. Kr¨uger, R. W. Schmitz, C. Schreiner, H. Gores, S. Passerini, and M. Winter, "Lithium difluoro(oxalato)borate: A promising salt for lithium metal based secondary batteries?," Electrochimica Acta, vol. 92, pp. 102-107, 03/01 2013, doi: 10.1016/j.electacta.2013.01.023.
[25] J. Qian, B. D. Adams, J. Zheng, W. Xu, W. A. Henderson, J. Wang, M. E. Bowden, S. Xu, J. Hu, and J.-G. Zhang, "Anode-Free Rechargeable Lithium Metal Batteries," Advanced Functional Materials, vol. 26, no. 39, pp. 7094-7102, 2016, doi: 10.1002/adfm.201602353.
[26] J. Alvarado, M. A. Schroeder, T. P. Pollard, X. Wang, J. Z. Lee, M. Zhang, T. Wynn, M. Ding, O. Borodin, and Y. S. Meng, "Bisalt ether electrolytes: a pathway towards lithium metal batteries with Ni-rich cathodes," Energy & Environmental Science, vol. 12, no. 2, pp. 780-794, 2019.
[27] S. Jiao, X. Ren, R. Cao, M. H. Engelhard, Y. Liu, D. Hu, D. Mei, J. Zheng, W. Zhao, and Q. Li, "Stable cycling of high-voltage lithium metal batteries in ether electrolytes," Nature Energy, vol. 3, no. 9, pp. 739-746, 2018.
[28] Y. Zhu, Y. Li, M. Bettge, and D. Abraham, "Positive electrode passivation by LiDFOB electrolyte additive in cells with Li1.2Ni0.15Mn0.55Co0.1O2 -based positive and graphite-based negative electrodes," J. Electrochem. Soc., vol. 159, pp. A2109-A2117, 01/01 2012.
[29] W. Zhao, G. Zheng, M. Lin, W. Zhao, D. Li, X. Guan, Y. Ji, G. F. Ortiz, and Y. Yang, "Toward a stable solid-electrolyte-interfaces on nickel-rich cathodes: LiPO2F2 salt-type additive and its working mechanism for LiNi0.5Mn0.25Co0.25O2 cathodes," Journal of power sources, vol. 380, pp. 149-157, 2018.
[30] J. Qian, B. D. Adams, J. Zheng, W. Xu, W. A. Henderson, J. Wang, M. E. Bowden, S. Xu, J. Hu, and J. G. Zhang, "Anode‐free rechargeable lithium metal batteries," Advanced Functional Materials, vol. 26, no. 39, pp. 7094-7102, 2016.
[31] J. Qian, W. A. Henderson, W. Xu, P. Bhattacharya, M. Engelhard, O. Borodin, and J.-G. Zhang, "High rate and stable cycling of lithium metal anode," Nature communications, vol. 6, no. 1, pp. 1-9, 2015.
[32] O. Borodin, J. Self, K. A. Persson, C. Wang, and K. Xu, "Uncharted Waters: Super-Concentrated Electrolytes," Joule, vol. 4, no. 1, pp. 69-100, 2020.
[33] T. T. Beyene, H. K. Bezabh, M. A. Weret, T. M. Hagos, C.-J. Huang, C.-H. Wang, W.-N. Su, H. Dai, and B.-J. Hwang, "Concentrated dual-salt electrolyte to stabilize Li metal and increase cycle life of anode free Li-metal batteries," Journal of The Electrochemical Society, vol. 166, no. 8, pp. A1501-A1509, 2019.
[34] R. Rodriguez, K. E. Loeffler, R. A. Edison, R. M. Stephens, A. Dolocan, A. Heller, and C. B. Mullins, "Effect of the Electrolyte on the Cycling Efficiency of Lithium-Limited Cells and their Morphology Studied Through in Situ Optical Imaging," ACS Applied Energy Materials, vol. 1, no. 11, pp. 5830-5835, 2018.
[35] A. A. Assegie, J.-H. Cheng, L.-M. Kuo, W.-N. Su, and B.-J. Hwang, "Polyethylene oxide film coating enhances lithium cycling efficiency of an anode-free lithium-metal battery," Nanoscale, vol. 10, no. 13, pp. 6125-6138, 2018.
[36] A. A. Assegie, C.-C. Chung, M.-C. Tsai, W.-N. Su, C.-W. Chen, and B.-J. Hwang, "Multilayer-graphene-stabilized lithium deposition for anode-Free lithium-metal batteries," Nanoscale, vol. 11, no. 6, pp. 2710-2720, 2019.
[37] L. H. Abrha, T. A. Zegeye, T. T. Hagos, H. Sutiono, T. M. Hagos, G. B. Berhe, C.-J. Huang, S.-K. Jiang, W.-N. Su, and Y.-W. Yang, "Li7La2.75Ca0.25Zr1.75Nb0.25O12@LiClO4 composite film derived solid electrolyte interphase for anode-free lithium metal battery," Electrochimica Acta, vol. 325, p. 134825, 2019.
[38] Z. T. Wondimkun, T. T. Beyene, M. A. Weret, N. A. Sahalie, C.-J. Huang, B. Thirumalraj, B. A. Jote, D. Wang, W.-N. Su, and C.-H. Wang, "Binder-free ultra-thin graphene oxide as an artificial solid electrolyte interphase for anode-free rechargeable lithium metal batteries," Journal of Power Sources, vol. 450, p. 227589, 2020.
[39] R. Xu, X. Q. Zhang, X. B. Cheng, H. J. Peng, C. Z. Zhao, C. Yan, and J. Q. Huang, "Artificial soft–rigid protective layer for dendrite‐free lithium metal anode," Advanced Functional Materials, vol. 28, no. 8, p. 1705838, 2018.
[40] Y. Liu, D. Lin, P. Y. Yuen, K. Liu, J. Xie, R. H. Dauskardt, and Y. Cui, "An artificial solid electrolyte interphase with high Li‐ion conductivity, mechanical strength, and flexibility for stable lithium metal anodes," Advanced Materials, vol. 29, no. 10, p. 1605531, 2017.
[41] X. B. Cheng, T. Z. Hou, R. Zhang, H. J. Peng, C. Z. Zhao, J. Q. Huang, and Q. Zhang, "Dendrite‐free lithium deposition induced by uniformly distributed lithium ions for efficient lithium metal batteries," Advanced materials, vol. 28, no. 15, pp. 2888-2895, 2016.
[42] F. Liu, Q. Xiao, H. B. Wu, L. Shen, D. Xu, M. Cai, and Y. Lu, "Fabrication of hybrid silicate coatings by a simple vapor deposition method for lithium metal anodes," Advanced Energy Materials, vol. 8, no. 6, p. 1701744, 2018.
[43] Z. Peng, N. Zhao, Z. Zhang, H. Wan, H. Lin, M. Liu, C. Shen, H. He, X. Guo, and J.-G. Zhang, "Stabilizing Li/electrolyte interface with a transplantable protective layer based on nanoscale LiF domains," Nano Energy, vol. 39, pp. 662-672, 2017.
[44] K. Yan, Z. Lu, H.-W. Lee, F. Xiong, P.-C. Hsu, Y. Li, J. Zhao, S. Chu, and Y. Cui, "Selective deposition and stable encapsulation of lithium through heterogeneous seeded growth," Nature Energy, vol. 1, no. 3, pp. 1-8, 2016.
[45] S. S. Zhang, X. Fan, and C. Wang, "A tin-plated copper substrate for efficient cycling of lithium metal in an anode-free rechargeable lithium battery," Electrochimica Acta, vol. 258, pp. 1201-1207, 2017.
[46] S. S. Zhang, X. Fan, and C. Wang, "An in-situ enabled lithium metal battery by plating lithium on a copper current collector," Electrochemistry Communications, vol. 89, pp. 23-26, 2018.
[47] P. Bai, J. Li, F. R. Brushett, and M. Z. Bazant, "Transition of lithium growth mechanisms in liquid electrolytes," Energy & Environmental Science, vol. 9, no. 10, pp. 3221-3229, 2016.
[48] A. J. Bard and L. R. Faulkner, "Fundamentals and applications," Electrochemical Methods, vol. 2, no. 482, pp. 580-632, 2001.
[49] H. J. Sand, "III. On the concentration at the electrodes in a solution, with special reference to the liberation of hydrogen by electrolysis of a mixture of copper sulphate and sulphuric acid," The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, vol. 1, no. 1, pp. 45-79, 1901.
[50] K. N. Wood, E. Kazyak, A. F. Chadwick, K.-H. Chen, J.-G. Zhang, K. Thornton, and N. P. Dasgupta, "Dendrites and pits: Untangling the complex behavior of lithium metal anodes through operando video microscopy," ACS central science, vol. 2, no. 11, pp. 790-801, 2016.
[51] A. J. Sanchez, E. Kazyak, Y. Chen, K.-H. Chen, E. R. Pattison, and N. P. Dasgupta, "Plan-View Operando Video Microscopy of Li Metal Anodes: Identifying the Coupled Relationships among Nucleation, Morphology, and Reversibility," ACS Energy Letters, vol. 5, no. 3, pp. 994-1004, 2020.
[52] K. C. Russell, "Nucleation in solids: the induction and steady state effects," Advances in Colloid and Interface Science, vol. 13, no. 3-4, pp. 205-318, 1980.
[53] W. Plieth, Electrochemistry for materials science. Elsevier, 2008.
[54] Y. D. Gamburg and G. Zangari, Theory and practice of metal electrodeposition. Springer Science & Business Media, 2011.
[55] C. T. Love, O. A. Baturina, and K. E. Swider-Lyons, "Observation of lithium dendrites at ambient temperature and below," ECS Electrochemistry Letters, vol. 4, no. 2, p. A24, 2015.
[56] M. Rosso, T. Gobron, C. Brissot, J.-N. Chazalviel, and S. Lascaud, "Onset of dendritic growth in lithium/polymer cells," Journal of power sources, vol. 97, pp. 804-806, 2001.
[57] K. Nishikawa, T. Mori, T. Nishida, Y. Fukunaka, and M. Rosso, "Li dendrite growth and Li+ ionic mass transfer phenomenon," Journal of electroanalytical chemistry, vol. 661, no. 1, pp. 84-89, 2011.
[58] J.-H. Cheng, A. A. Assegie, C.-J. Huang, M.-H. Lin, A. M. Tripathi, C.-C. Wang, M.-T. Tang, Y.-F. Song, W.-N. Su, and B. J. Hwang, "Visualization of lithium plating and stripping via in operando transmission x-ray microscopy," The Journal of Physical Chemistry C, vol. 121, no. 14, pp. 7761-7766, 2017.
[59] J. Steiger, D. Kramer, and R. Mönig, "Mechanisms of dendritic growth investigated by in situ light microscopy during electrodeposition and dissolution of lithium," Journal of Power Sources, vol. 261, pp. 112-119, 2014.
[60] J. Steiger, D. Kramer, and R. Mönig, "Microscopic observations of the formation, growth and shrinkage of lithium moss during electrodeposition and dissolution," Electrochimica Acta, vol. 136, pp. 529-536, 2014.
[61] A. J. Leenheer, K. L. Jungjohann, K. R. Zavadil, J. P. Sullivan, and C. T. Harris, "Lithium electrodeposition dynamics in aprotic electrolyte observed in situ via transmission electron microscopy," ACS nano, vol. 9, no. 4, pp. 4379-4389, 2015.
[62] S.-H. Yu, X. Huang, J. D. Brock, and H. c. D. Abruña, "Regulating key variables and visualizing lithium dendrite growth: an operando X-ray study," Journal of the American Chemical Society, vol. 141, no. 21, pp. 8441-8449, 2019.
[63] X.-B. Cheng, R. Zhang, C.-Z. Zhao, and Q. Zhang, "Toward safe lithium metal anode in rechargeable batteries: a review," Chemical reviews, vol. 117, no. 15, pp. 10403-10473, 2017.
[64] K. N. Wood, M. Noked, and N. P. Dasgupta, "Lithium metal anodes: toward an improved understanding of coupled morphological, electrochemical, and mechanical behavior," ACS Energy Letters, vol. 2, no. 3, pp. 664-672, 2017.
[65] A. Pei, G. Zheng, F. Shi, Y. Li, and Y. Cui, "Nanoscale nucleation and growth of electrodeposited lithium metal," Nano letters, vol. 17, no. 2, pp. 1132-1139, 2017.
[66] G. Rong, X. Zhang, W. Zhao, Y. Qiu, M. Liu, F. Ye, Y. Xu, J. Chen, Y. Hou, and W. Li, "Liquid‐Phase Electrochemical Scanning Electron Microscopy for In Situ Investigation of Lithium Dendrite Growth and Dissolution," Advanced Materials, vol. 29, no. 13, p. 1606187, 2017.
[67] B. L. Mehdi, J. Qian, E. Nasybulin, C. Park, D. A. Welch, R. Faller, H. Mehta, W. A. Henderson, W. Xu, and C. M. Wang, "Observation and quantification of nanoscale processes in lithium batteries by operando electrochemical (S) TEM," Nano letters, vol. 15, no. 3, pp. 2168-2173, 2015.
[68] "接觸式表面粗糙度、形狀量測儀器," https://www.keyence.com.tw/ss/products/microscope/roughness/equipment/line_01.jsp.
[69] "表面粗度," https://tw.misumi-ec.com/pdf/tech/MSM1/Surface_Roughness.pdf.
[70] M. B. Pinson and M. Z. Bazant, "Theory of SEI formation in rechargeable batteries: capacity fade, accelerated aging and lifetime prediction," Journal of the Electrochemical Society, vol. 160, no. 2, p. A243, 2012.
[71] H. J. Ploehn, P. Ramadass, and R. E. White, "Solvent diffusion model for aging of lithium-ion battery cells," Journal of The Electrochemical Society, vol. 151, no. 3, p. A456, 2004.
[72] X. Q. Zhang, X. B. Cheng, X. Chen, C. Yan, and Q. Zhang, "Fluoroethylene carbonate additives to render uniform Li deposits in lithium metal batteries," Advanced Functional Materials, vol. 27, no. 10, p. 1605989, 2017.
[73] A. Nurpeissova, D.-I. Park, S.-S. Kim, and Y.-K. Sun, "Epicyanohydrin as an interface stabilizer agent for cathodes of Li-ion batteries," Journal of The Electrochemical Society, vol. 163, no. 2, p. A171, 2015.
[74] Q. Zhang, J. Pan, P. Lu, Z. Liu, M. W. Verbrugge, B. W. Sheldon, Y.-T. Cheng, Y. Qi, and X. Xiao, "Synergetic effects of inorganic components in solid electrolyte interphase on high cycle efficiency of lithium ion batteries," Nano Letters, vol. 16, no. 3, pp. 2011-2016, 2016.
[75] K. Leung, "Electronic structure modeling of electrochemical reactions at electrode/electrolyte interfaces in lithium ion batteries," The Journal of Physical Chemistry C, vol. 117, no. 4, pp. 1539-1547, 2013.
[76] C. Yan, Y. X. Yao, X. Chen, X. B. Cheng, X. Q. Zhang, J. Q. Huang, and Q. Zhang, "Lithium nitrate solvation chemistry in carbonate electrolyte sustains high‐voltage lithium metal batteries," Angewandte Chemie International Edition, vol. 57, no. 43, pp. 14055-14059, 2018.
[77] T. Schedlbauer, S. Krüger, R. Schmitz, R. Schmitz, C. Schreiner, H. Gores, S. Passerini, and M. Winter, "Lithium difluoro (oxalato) borate: A promising salt for lithium metal based secondary batteries?," Electrochimica Acta, vol. 92, pp. 102-107, 2013.