由於自然資源的減少及全球對能源的需求日益增加，環保且高效儲能材料成為熱門研究議題。鋰離子電池（LIBs）因其高能量密度與電容量為現在最廣泛使用的储能裝置。過量鋰Li1.2Ni0.2Mn0.6O2層狀陰極材料具有高容量及能量密度的特性而可望成為下世代陰極材料。然而電池充電到高電壓時易產生氧氣而導致電容量衰退和陰極腐蝕。有關O2產生的機制仍然存在很大的不確定性。在本論文中，我們證明了在Li1.2Ni0.2Mn0.6O2充電過程中Ni和O為主要的活化物質。氧氣的生成熱與bader charge分析結果顯示在高充電狀態下氧原子有很大的可能性形成氧氣。為了應對在高充電狀態下陰極材料的氧流損和電容量衰退問題，我們通常運用絕緣材料塗層來解決。然而塗層可能會降低Li離子在內部的擴散速度。在本論文中我們應用了LiZrO2塗層在陰極表面上來解決速率問題。本論的研究成果顯示，與Li1.2Ni0.2Mn0.6O2（003）表面相比，LiZrO2不僅可以維持Li1.2Ni0.2Mn0.6O2（003）表面的晶格參數，而且可以降低O2的產生。另一方面，我們的態密度（DOS）分析結果顯示LiZrO2塗層不影響Li1.2Ni0.2Mn0.6O2（003）表面的電子傳導性。在不同充電狀態下，Li1.2Ni0.2Mn0.6O2（003）表面系統中O2產生的能障計算結果顯示，O2的產生的難易程度與陰極的脫鋰程度有很大的關係。

The diminishing natural resources and the increasing global demands for energy have led to an increase in research on clean and efficient energy storage materials. With this regard, rechargeable batteries have shown a tremendous promise as energy storage devices. Li-ion batteries (LIBs), a type of rechargabel batteries, have been regarded as a viable choice to help mitigate the energy shortage and have shown superb performance and energy density. Currently, the applications of LIBs extend from small and portable devices to electric vehicles. Extensive researches have been made to identify potential anode, cathode and electrolyte materials to improve the performance of LIBs. Among the widely studied cathode materials, layered cathode materials, such as Li1.2Ni0.2Mn0.6O2, which can deliver high capacity and energy density are of great interest. Mechanisms involving simultaneous Li and O removal is often studied to answer why capacity fading and cathode corrosion occure when the battery is charged to high voltages. However, there is still substantial uncertainty about the process of O2 evolution in these cathode materials. In this thesis, we demonstrate the electrochemical active role of Ni and O in Li1.2Ni0.2Mn0.6O2 during the charging process. Importantly, we will show the high tendency for O atoms, which bond with both Li and Mn at transition metal layer of Li1.2Ni0.2Mn0.6O2, to form O2 at high de-intercalation levels. To deal with the O loss and capacity fading problem of the cathode material when operating at high voltages, we proposed the LiZrO2 coating as a strategy, which is different from the traditional ZrO2 that lower the rate performance of the cathode. Our DFT calculation shows that the LiZrO2 can not only maintain the lattice parameters of Li1.2Ni0.2Mn0.6O2 (003) surface but also reduce the O2 evolution compared to bare Li1.2Ni0.2Mn0.6O2 (003) surface. In addition, our density of states (DOS) calculation shows that LiZrO2 coating does not effect the electronic conductivity of Li1.2Ni0.2Mn0.6O2 (003) surface. The calculated reaction barrier for O2 evolution in Li1.2Ni0.2Mn0.6O2 (003) surface at different intercalation levels indicates that the tendency of O2 evolution is highly dependent on the degree of delithiation.

1. NederhoffE. Transport Energy and CO2 : Moving towards Sustainability - Books - OECD iLibrary.; 2009. doi:10.1787/9789264073173-en.
2. ChengF, LiangJ, TaoZ, ChenJ. Functional materials for rechargeable batteries. Adv Mater. 2011;23(15):1695-1715. doi:10.1002/adma.201003587.
3. BeckF, RüetschiP. Rechargeable batteries with aqueous electrolytes. Electrochim Acta. 2000;45(15-16):2467-2482. doi:10.1016/S0013-4686(00)00344-3.
4. WHITTINGHAMMS. Electrical Energy Storage and Intercalation Chemistry. Science (80- ). 1976;192(4244):1126-1127. doi:10.1126/science.192.4244.1126.
5. MizushimaK, JonesPC, WisemanPJ, GoodenoughJB. LixCoO2 (0<x<-1): A new cathode material for batteries of high energy density. Mater Res Bull. 1980;15(6):783-789. doi:10.1016/0025-5408(80)90012-4.
6. OhzukuT, UedaA, NagayamaM. Electrochemistry and Structural Chemistry of Linio2 (R(3)over-Bar-M) for 4 Volt Secondary Lithium Cells. J Electrochem Soc. 1993;140(7):1862-1870. doi:Doi 10.1149/1.2220730.
7. XiaH, MengYS, LuL, CederG, AllianceS. Electrochemical behavior and Li Diffusion study of LiCoO 2 thin film electrodes prepared by PLD. Sci Commons. 2010:http://en.scientificcommons.org/20613936. http://hdl.handle.net/1721.1/35827%5Cnhttp://en.scientificcommons.org/20613936.
8. RozierP, TarasconJM. Review—Li-Rich Layered Oxide Cathodes for Next-Generation Li-Ion Batteries: Chances and Challenges. J Electrochem Soc. 2015;162(14):A2490-A2499. doi:10.1149/2.0111514jes.
9. MohantyD, KalnausS, MeisnerR a., et al. Structural transformation of a lithium-rich Li1.2Co0.1Mn0.55Ni0.15O2 cathode during high voltage cycling resolved by in situ X-ray diffraction. J Power Sources. 2013;229:239-248. doi:10.1016/j.jpowsour.2012.11.144.
10. YamadaA, ChungSC, HinokumaK. Optimized LiFePO4 for lithium battery cathodes. J Electrochem Soc. 2001;148(3):A224-A229. doi:10.1149/1.1348257.
11. AmriouT, KhelifaB, AouragH, AouadiSM, MathieuC. Ab initio investigation of the Jahn-Teller distortion effect on the stabilizing lithium intercalated compounds. Mater Chem Phys. 2005;92(2-3):499-504. doi:10.1016/j.matchemphys.2005.01.061.
12. ThongtemT, ThongtemS. Characterization of Li1−xNi1+xO2 prepared using succinic acid as a complexing agent. Inorg Mater. 2006;42(2):202-209. doi:10.1134/S0020168506020166.
13. AraiH. Thermal behavior of Li1−yNiO2 and the decomposition mechanism. Solid State Ionics. 1998;109(3-4):295-302. doi:10.1016/S0167-2738(98)00075-7.
14. StoyanovaR, ZhechevaE, AlcántaraR, et al. Lithium/nickel mixing in the transition metal layers of lithium nickelate: High-pressure synthesis of layered Li[LixNi1-x]O 2 oxides as cathode materials for lithium-ion batteries. Solid State Ionics. 2003;161(3-4):197-204. doi:10.1016/S0167-2738(03)00280-7.
15. StewartSG, SrinivasanV, NewmanJ. Modeling the Performance of Lithium-Ion Batteries and Capacitors during Hybrid-Electric-Vehicle Operation. J Electrochem Soc. 2008;155(9):A664. doi:10.1149/1.2953524.
16. MarthaSK, SclarH, Szmuk FramowitzZ, et al. A comparative study of electrodes comprising nanometric and submicron particles of LiNi0.50Mn0.50O2, LiNi0.33Mn0.33Co0.33O2, and LiNi0.40Mn0.40Co0.20O2 layered compounds. J Power Sources. 2009;189(1):248-255. doi:10.1016/j.jpowsour.2008.09.090.
17. LuCH, LinYK. Microemulsion preparation and electrochemical characteristics of LiNi1/3Co1/3Mn1/3O2 powders. J Power Sources. 2009;189(1):40-44. doi:10.1016/j.jpowsour.2008.12.036.
18. YanJ, LiuX, LiB. Recent progress in Li-rich layered oxides as cathode materials for Li-ion batteries. RSC Adv. 2014;4(108):63268-63284. doi:10.1039/C4RA12454E.
19. KimDK, MuralidharanP, LeeH, et al. Spinel LiMn2O4 nanorods as lithium ion battery cathodes. Nano Lett. 2008;8(11):3948-3952. doi:10.1021/nl8024328.
20. YiTF, ZhuYR, ZhuXD, ShuJ, YueCB, ZhouAN. A review of recent developments in the surface modification of LiMn2O4 as cathode material of power lithium-ion battery. Ionics (Kiel). 2009;15(6):779-784. doi:10.1007/s11581-009-0373-x.
21. ThackerayM, deKockA, DavidWIF. Synthesis and structural characterization of defect spinels in the lithium-manganese-oxide system. Mater Res Bull. 1993;28(10):1041-1049. doi:10.1016/0025-5408(93)90142-Z.
22. FergusJW. Recent developments in cathode materials for lithium ion batteries. J Power Sources. 2010;195(4):939-954. doi:10.1016/j.jpowsour.2009.08.089.
23. LiuQ, MaoD, ChangC, HuangF. Phase conversion and morphology evolution during hydrothermal preparation of orthorhombic LiMnO2 nanorods for lithium ion battery application. J Power Sources. 2007;173(1):538-544. doi:10.1016/j.jpowsour.2007.03.077.
24. YunjianL, XinhaiL, HuajunG, et al. Electrochemical performance and capacity fading reason of LiMn2O4/graphite batteries stored at room temperature. J Power Sources. 2009;189(1):721-725. doi:10.1016/j.jpowsour.2008.08.044.
25. DoiT, InabaM, TsuchiyaH, et al. Electrochemical AFM study of LiMn2O4 thin film electrodes exposed to elevated temperatures. J Power Sources. 2008;180(1):539-545. doi:10.1016/j.jpowsour.2008.02.054.
26. LiX, XuY, WangC. Suppression of Jahn-Teller distortion of spinel LiMn2O4 cathode. J Alloys Compd. 2009;479(1-2):310-313. doi:10.1016/j.jallcom.2008.12.081.
27. PadhiAK, NanjundaswamyKS, GoodenoughJB. Phospho-olivines as Positive-Electrode Materials for Rechargeable Lithium Batteries. J Electrochem Soc. 1997;144(4):1188-1194. doi:10.1149/1.1837571.
28. PadhiAK, NanjundaswamyKS, MasquelierC, OkadaS, GoodenoughJB. Effect of structure on the Fe3+/Fe2+ redox couple in iron phosphates. J Electrochem Soc. 1997;144(5):1609-1613. doi:Doi 10.1149/1.1837649.
29. WhittinghamMS. Lithium batteries and cathode materials. Chem Rev. 2004;104(10):4271-4301. doi:10.1021/cr020731c.
30. RavetN, ChouinardY, MagnanJF, BesnerS, GauthierM, ArmandM. Electroactivity of natural and synthetic triphylite. In: Journal of Power Sources. Vol 97-98. ; 2001:503-507. doi:10.1016/S0378-7753(01)00727-3.
31. ShiratsuchiT, OkadaS, DoiT, YamakiJ ichi. Cathodic performance of LiMn1-xMxPO4 (M = Ti, Mg and Zr) annealed in an inert atmosphere. Electrochim Acta. 2009;54(11):3145-3151. doi:10.1016/j.electacta.2008.11.069.
32. BramnikNN, NikolowskiK, TrotsDM, EhrenbergH. Thermal Stability of LiCoPO4 Cathodes. Electrochem Solid-State Lett. 2008;11(6):A89-A93. doi:10.1149/1.2894902.
33. KaskhedikarNA, MaierJ. Lithium storage in carbon nanostructures. Adv Mater. 2009;21(25-26):2664-2680. doi:10.1002/adma.200901079.
34. ZhuG-N, WangY-G, XiaY-Y. Ti-based compounds as anode materials for Li-ion batteries. Energy {&} Environ Sci. 2012;5(5):6652. doi:10.1039/c2ee03410g.
35. JainA, OngSP, HautierG, et al. Commentary: The materials project: A materials genome approach to accelerating materials innovation. APL Mater. 2013;1(1). doi:10.1063/1.4812323.
36. ChocklaAM, KlavetterKC, MullinsCB, KorgelBA. Solution-grown germanium nanowire anodes for lithium-ion batteries. ACS Appl Mater Interfaces. 2012;4(9):4658-4664. doi:10.1021/am3010253.
37. ParkC-M, KimJ-H, KimH, SohnH-J. Li-alloy based anode materials for Li secondary batteries. Chem Soc Rev. 2010;39(8):3115. doi:10.1039/b919877f.
38. WenY, HeK, ZhuY, et al. Expanded graphite as superior anode for sodium-ion batteries. Nat Commun. 2014;5(May):4033. doi:10.1038/ncomms5033.
39. NozakiH, NagaokaK, HoshiK, OhtaN, InagakiM. Carbon-coated graphite for anode of lithium ion rechargeable batteries: Carbon coating conditions and precursors. J Power Sources. 2009;194(1):486-493. doi:10.1016/j.jpowsour.2009.05.040.
40. HanX, OuyangM, LuL, LiJ. Cycle life of commercial lithium-ion batteries with lithium titanium oxide anodes in electric vehicles. Energies. 2014;7(8):4895-4909. doi:10.3390/en7084895.
41. YangJ. Small particle size multiphase Li-alloy anodes for lithium-ionbatteries. Solid State Ionics. 1996;90(1-4):281-287. doi:10.1016/S0167-2738(96)00389-X.
42. LiQ, ChenJ, FanL, KongX, LuY. Progress in Electrolytes for Rechargeable Li-based Batteries and beyond. Green Energy Environ. 2016;1:1-25. doi:10.1016/j.gee.2016.04.006.
43. CroyJR, AbouimraneA, ZhangZ. Next-generation lithium-ion batteries: The promise of near-term advancements. MRS Bull. 2014;39(5):407-415. doi:DOI: 10.1557/mrs.2014.84.
44. DahbiM, GhamoussF, Tran-VanF, LemordantD, AnoutiM. Comparative study of EC/DMC LiTFSI and LiPF6 electrolytes for electrochemical storage. J Power Sources. 2011;196(22):9743-9750. doi:10.1016/j.jpowsour.2011.07.071.
45. LuZ, DahnJR. Understanding the Anomalous Capacity of Li/Li[Ni[sub x]Li[sub (1/3−2x/3)]Mn[sub (2/3−x/3)]]O[sub 2] Cells Using In Situ X-Ray Diffraction and Electrochemical Studies. J Electrochem Soc. 2002;149(7):A815. doi:10.1149/1.1480014.
46. LeeDK, ParkSH, AmineK, BangHJ, ParakashJ, SunYK. High capacity Li[Li0.2Ni0.2Mn0.6]O2 cathode materials via a carbonate co-precipitation method. J Power Sources. 2006;162(2 SPEC. ISS.):1346-1350. doi:10.1016/j.jpowsour.2006.07.064.
47. ArmstrongAR, HolzapfelM, NovákP, et al. Demonstrating oxygen loss and associated structural reorganization in the lithium battery cathode Li[Ni0.2Li0.2Mn 0.6]O2. J Am Chem Soc. 2006;128(26):8694-8698. doi:10.1021/ja062027+.
48. FuLJ, LiuH, LiC, et al. Surface modifications of electrode materials for lithium ion batteries. Solid State Sci. 2006;8(2):113-128. doi:10.1016/j.solidstatesciences.2005.10.019.
49. ChenZ, QinY, AmineK, SunY-K. Role of surface coating on cathode materials for lithium-ion batteries. J Mater Chem. 2010;20(36):7606-7612. doi:10.1039/c0jm00154f.
50. JungYS, CavanaghAS, RileyLA, et al. Ultrathin direct atomic layer deposition on composite electrodes for highly durable and safe Li-Ion batteries. Adv Mater. 2010;22(19):2172-2176. doi:10.1002/adma.200903951.
51. ChenZ, DahnJR. Effect of a ZrO2 Coating on the Structure and Electrochemistry of LixCoO2 When Cycled to 4.5 V. Electrochem Solid-State Lett. 2002;5(10):A213. doi:10.1149/1.1503202.
52. BelharouakI, JohnsonC, AmineK. Synthesis and electrochemical analysis of vapor-deposited carbon-coated LiFePO4. Electrochem commun. 2005;7(10):983-988. doi:10.1016/j.elecom.2005.06.019.
53. KimJY, LimDY. Surface-modified membrane as a separator for lithium-ion polymer battery. Energies. 2010;3(4):866-885. doi:10.3390/en3040866.
54. SunY-K, LeeY-S, YoshioM, AmineK. Synthesis and Electrochemical Properties of ZnO-Coated LiNi[sub 0.5]Mn[sub 1.5]O[sub 4] Spinel as 5 V Cathode Material for Lithium Secondary Batteries. Electrochem Solid-State Lett. 2002;5:A99. doi:10.1149/1.1465375.
55. XiaoX, LuP, AhnD. Ultrathin multifunctional oxide coatings for lithium ion batteries. Adv Mater. 2011;23(34):3911-3915. doi:10.1002/adma.201101915.
56. ZhangL, LiangG, PengG, et al. Significantly Improved Electrochemical Performance in Li 3 V 2 ( PO 4 ) 3 / C Promoted by SiO 2 Coating for Lithium-Ion Batteries. J Phys Chem. 2012;116:12401-12408. doi:10.1016/j.jpowsour.2015.06.121.
57. KweonHJ, KimSJ, ParkDG. Modification of LixNi1-yCoyO2 by applying a surface coating of MgO. J Power Sources. 2000;88(2):255-261. doi:10.1016/S0378-7753(00)00368-2.
58. KimYJ, ChoJ, KimTJ, ParkB. Suppression of Cobalt Dissolution from the LiCoO2 Cathodes with Various Metal-Oxide Coatings. J Electrochem Soc. 2003;150:A1723-A1725. doi:10.1149/1.1627347.
59. ZhaoJ, WangY. Atomic layer deposition of epitaxial ZrO2 coating on LiMn2O4 nanoparticles for high-rate lithium ion batteries at elevated temperature. Nano Energy. 2013;2(5):882-889. doi:10.1016/j.nanoen.2013.03.005.
60. JungYS, CavanaghAS, DillonAC, GronerMD, GeorgeSM, LeeS-H. Enhanced Stability of LiCoO[sub 2] Cathodes in Lithium-Ion Batteries Using Surface Modification by Atomic Layer Deposition. J Electrochem Soc. 2010;157(1):A75. doi:10.1149/1.3258274.
61. JungSC, HanYK. How do Li atoms pass through the Al2O3 coating layer during lithiation in Li-ion batteries? J Phys Chem Lett. 2013;4(16):2681-2685. doi:10.1021/jz401231e.
62. ZhangLL, ChenJJ, ChengS, XiangHF. Enhanced electrochemical performances of Li1.2Ni0.2Mn0.6O2 cathode materials by coating LiAlO2 for lithium-ion batteries. Ceram Int. 2016;42(1):1870-1878. doi:10.1016/j.ceramint.2015.09.154.
63. KresseG, FurthmüllerJ. Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Comput Mater Sci. 1996;6(1):15-50. doi:10.1016/0927-0256(96)00008-0.
64. BlöchlPE. Projector augmented-wave method. Phys Rev B. 1994;50(24):17953-17979. doi:10.1103/PhysRevB.50.17953.
65. GieseTJ, YorkDM. Density-functional expansion methods: Evaluation of LDA, GGA, and meta-GGA functionals and different integral approximations. J Chem Phys. 2010;133(24). doi:10.1063/1.3515479.
66. LiechtensteinAI, AnisimovVI, ZaanenJ. Density-functional theory and strong interactions: Orbital ordering in Mott-Hubbard insulators. Phys Rev B. 1995;52(8). doi:10.1103/PhysRevB.52.R5467.
67. HinumaY, MengYS, KangK, CederG. Phase transitions in the LiNi0.5Mn0.5O2 system with temperature. Chem Mater. 2007;19(7):1790-1800. doi:10.1021/cm062903i.
68. SheppardD, XiaoP, ChemelewskiW, JohnsonDD, HenkelmanG. A generalized solid-state nudged elastic band method. J Chem Phys. 2012;136(7). doi:10.1063/1.3684549.
69. HenkelmanG, UberuagaBP, JónssonH. Climbing image nudged elastic band method for finding saddle points and minimum energy paths. J Chem Phys. 2000;113(22):9901-9904. doi:10.1063/1.1329672.
70. OngSP, ChevrierVL, HautierG, et al. Voltage, stability and diffusion barrier differences between sodium-ion and lithium-ion intercalation materials. Energy Environ Sci. 2011;4(9):3680. doi:10.1039/c1ee01782a.
71. YoonWS, IannopolloS, GreyCP, et al. Local structure and cation ordering in O3 lithium nickel manganese oxides with stoichiometry Li NixMn(2-x)/3Li(1-2x)/3 O-2 - NMR studies and first principles calculations. Electrochem Solid State Lett. 2004;7(7):A167-A171. doi:10.1149/1.1737711.
72. LuZ, BeaulieuLY, DonabergerRA, ThomasCL, DahnJR. Synthesis, Structure, and Electrochemical Behavior of Li[Ni[sub x]Li[sub 1/3−2x/3]Mn[sub 2/3−x/3]]O[sub 2]. J Electrochem Soc. 2002;149(6):A778. doi:10.1149/1.1471541.
73. MengYS, CederG, GreyCP, et al. Cation Ordering in Layered O3 Li[Ni x Li 1/3 - 2 x /3 Mn 2/ 3 - x /3 ]O 2 (0 ≤ x ≤ 1 / 2 ) Compounds. Chem Mater. 2005;17(9):2386-2394. doi:10.1021/cm047779m.
74. CahillLS, YinS-C, SamosonA, HeinmaaI, NazarLF, GowardGR. 6 Li NMR Studies of Cation Disorder and Transition Metal Ordering in Li[Ni 1/3 Mn 1/3 Co 1/3 ]O 2 Using Ultrafast Magic Angle Spinning. Chem Mater. 2005;17(26):6560-6566. doi:10.1021/cm0508773.
75. O’HandleyRC. Modern Magnetic Materials: Principles and Applications. John Wiley Sons New York Chichester Weinheim Brisbane Singapore Toronto. 2000:768. doi:10.1109/MEI.2005.1490004.
76. DixitM, KosaM, LaviOS, MarkovskyB, AurbachD, MajorDT. Thermodynamic and kinetic studies of LiNi0.5Co0.2Mn0.3O2 as a positive electrode material for Li-ion batteries using first principles. Phys Chem Chem Phys. 2016;18(9):6799-6812. doi:10.1039/c5cp07128c.
77. ZengD, CabanaJ, BrégerJ, YoonW-S, GreyCP. Cation Ordering in Li[NixMnxCo(1-2x)O2-Layered Cathode Materials: A Nuclear Magnetic Resonance (NMR), Pair Distribution Function, X-ray Absorption Spectroscopy, and Electrochemical Study. Chem Mater. 2007;19(25):6277-6289. doi:10.1021/cm702241a.
78. GoodenoughJB, ParkKS. The Li-ion rechargeable battery: A perspective. J Am Chem Soc. 2013;135(4):1167-1176. doi:10.1021/ja3091438.
79. LiuC, NealeZG, CaoG. Understanding electrochemical potentials of cathode materials in rechargeable batteries. Mater Today. 2016;19(2):109-123. doi:10.1016/j.mattod.2015.10.009.
80. DixitM, EngelH, EitanR, et al. Classical and Quantum Modeling of Li and Na Diffusion in FePO 4. J Phys Chem C. 2015;119(28):15801-15809. doi:10.1021/acs.jpcc.5b00405.
81. XuS, JacobsRM, NguyenHM, et al. Lithium transport through lithium-ion battery cathode coatings. J Mater Chem A. 2015;3(33):17248-17272. doi:10.1039/C5TA01664A.