Polarity-tuned Gel Polymer Electrolyte Coating of High-voltage LiCoO_2 Cathode Materials
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We demonstrate a new surface modification of high-voltage lithium cobalt oxide (LiCoO_2) cathode active materials for lithium-ion batteries. This approach is based on exploitation of a polarity-tuned gel polymer electrolyte (GPE) coating. Herein, two contrast polymers having different polarity are chosen: polyimide (PI) synthesized from thermally curing 4-component (pyromellitic dianhydride/biphenyl dianhydride/phenylenediamine/oxydianiline) polyamic acid (as a polar GPE) and ethylene-vinyl acetate copolymer (EVA) containing 12 wt% vinyl acetate repeating unit (as a less polar GPE). The strong affinity of polyamic acid for LiCoO_2 allows the resulting PI coating layer to present a highly-continuous surface film of nanometer thickness. On the other hand, the less polar EVA coating layer is poorly deposited onto the LiCoO_2, resulting in a locally agglomerated morphology with relatively high thickness. Based on the characterization of GPE coating layers, their structural difference on the electrochemical performance and thermal stability of high-voltage (herein, 4.4 V) LiCoO_2 is thoroughly investigated. In comparison to the EVA coating layer, the PI coating layer is effective in preventing the direct exposure of LiCoO_2 to liquid electrolyte, which thus plays a viable role in improving the high-voltage cell performance and mitigating the interfacial exothermic reaction between the charged LiCoO_2 and liquid electrolytes.
Abstract
We demonstrate a new surface modification of high-voltage lithium cobalt oxide (LiCoO_2) cathode active materials for lithium-ion batteries. This approach is based on exploitation of a polarity-tuned gel polymer electrolyte (GPE) coating. Herein, two contrast polymers having different polarity are chosen: polyimide (PI) synthesized from thermally curing 4-component (pyromellitic dianhydride/biphenyl dianhydride/phenylenediamine/oxydianiline) polyamic acid (as a polar GPE) and ethylene-vinyl acetate copolymer (EVA) containing 12 wt% vinyl acetate repeating unit (as a less polar GPE). The strong affinity of polyamic acid for LiCoO_2 allows the resulting PI coating layer to present a highly-continuous surface film of nanometer thickness. On the other hand, the less polar EVA coating layer is poorly deposited onto the LiCoO_2, resulting in a locally agglomerated morphology with relatively high thickness. Based on the characterization of GPE coating layers, their structural difference on the electrochemical performance and thermal stability of high-voltage (herein, 4.4 V) LiCoO_2 is thoroughly investigated. In comparison to the EVA coating layer, the PI coating layer is effective in preventing the direct exposure of LiCoO_2 to liquid electrolyte, which thus plays a viable role in improving the high-voltage cell performance and mitigating the interfacial exothermic reaction between the charged LiCoO_2 and liquid electrolytes.
참고문헌 (27)
- J. Thomas, "A spectacularly reactive cathode’", Nat.Mater, 2, pp.705~ (2003)
- M. S. Whittingham, "Lithium batteries and cathodematerials’", Chem. Rev, 104, pp.4271~ (2004)
- H. Li, "Research onadvanced materials for Li-ion batteries’", Adv. Mater, 21, pp.4593~ (2009)
- M. R. Palacin, "Recent advances in rechargeable batterymaterials: a chemist’s perspective’", Chem. Soc. Rev, 38, pp.2565~ (2009)
- B. L. Ellis, "Positive electrodematerials for Li-ion and Li-batteries’", Chem. Mater, 22, pp.691~ (2010)
- J. B. Goodenough, "Challenges for rechargeableLi batteries", Chem. Mater, 22, pp.587~ (2010)
- K. S. Lee, "Improvement of high voltage cycling performance andthermal stability of lithium-ion cells by use of a thiopheneadditive’", Electrochem. Comm, 11, pp.1900~ (2009)
- A. Abouimrane, "Sulfonebasedelectrolytes for high-voltage Li-ion batteries", Electrochem. Comm, 11, pp.1073~ (2009)
- Y. K. Sun, "Significant improvement of high voltage cycling behavior AlF3-coated LiCoO2 cathode", ELECTROCHEMISTRY COMMUNICATIONS, 8, pp.821~826, ELSEVIER SCIENCE INC
- Y. K. Sun, "Effect of AlF3 coating amount on high voltagecycling performance of LiCoO2’", Electrochim. Acta, 53, pp.1013~ (2007)
- D. Aurbach, "‘On the capacityfading of LiCoO2 intercalation electrodes: the effect ofcycling, storage, temperature, and surface film formingadditives’", Electrochim. Acta, 47, pp.4291~ (2002)
- H. Miyashiro, "Improvement of degradation atelevated temperature and at high state-of-charge storageby ZrO2 coating on LiCoO2’", J. Electrochem. Soc, 153, pp.348~ (2006)
- Z. Chen, "Methods to obtain excellentcapacity retention in LiCoO2 cycled to 4.5V’", Electrochim.Acta, 49, pp.1079~ (2004)
- Z. Chen, "Effect of a ZrO2 coating on thestructure and electrochemistry of LixCoO2 when cycledto 4.5 V’", Electrochem. Solid State Lett, 5, pp.213~ (2002)
- W. Chang, "Effectsof ZnO coating on electrochemical performance andthermal stability of LiCoO2 as cathode material for lithiumionbatteries", J. Power Sources, 195, pp.320~ (2010)
- J. Saunier, "‘Thinand flexible lithium-ion batteries: investigation of polymerelectrolytes’", J. Power Sources, 119, pp.454~ (2003)
- S. Y. Lee, "Phase behaviorof gel-type polymer electrolytes and its influence onelectrochemical properties", ChemPhysChem, 6, pp.49~ (2005)
- A. M. Stephan, "Review on gel polymer electrolytes forlithium batteries’", Eur. Polym. J, 42, pp.21~ (2006)
- F. Ciuffa, "Lithium and proton conducting gel-type membranes’", J.Power Sources, 127, pp.53~ (2004)
- M. C. Choi, "Polymers for flexibledisplays: From material selection to device applications", Prog. Polym. Sci, 33, pp.581~ (2008)
- L. Y. Jiang, "Polyimides membranes for pervaporation and biofuelsseparation’", Prog. Polym. Sci, 34, pp.1135~ (2009)
- W. Essafi, "Sulfonated polyimideionomers: a structural study’", Macromolecules, 37, pp.1431~ (2004)
- H. C. Liou, "Thicknessdependence of the anisotropy in thermal expansion ofPMDA-ODA and BPDA-PDA thin films’", Thin SolidFilms, 339, pp.68~ (1999)
- J. H. Park, "Polyimide gel polymer electrolyte-nanoencapsulated LiCoO2 cathode materials for high-voltage Li-ion batteries", ELECTROCHEMISTRY COMMUNICATIONS, 12(8), pp.1099~1102, ELSEVIER SCIENCE INC
- J. Brandrup, "Polymer handbook 3rdedition" (1999), Wiley
- H. S. Jeong, "A novel poly(vinylidene fluoride-hexafluoropropylene)", poly(ethyleneterephthalate) composite nonwoven separator with phaseinversion-controlled microporous structure for a lithiumionbattery, 2010, pp.20, 9180~
- J. H. Park, "Close-packedSiO2", poly (methyl methacrylate) binary nanoparticlescoatedpolyethylene separators for lithium-ion batteries, 2010, pp.195, 8306~