Fischer, J.

Leiste, H.

Seemann, K.

Seifert, H.J.

Strafela, M.

Ulrich, S.

Seifert, H. J.

KITopen

KIT – University of the State of Baden-Wuerttemberg and National Research Center of the Helmholtz Association Microstructural and electrochemical comparison of as deposited and heat treated Li-Ni-Mn-Co-O thin film cathodes for Lithium-ion batteries M. Strafela, J. Fischer, K. Seemann, H. Leiste, H.J. Seifert, S. Ulrich  LiBD-7  2015 – “Electrode materials” Conclusions and Outlook: Acknowledgment: The authors gratefully acknowledge the financial support by the Helmholtz-Portfolio-project  “Elektrochemische Speicher im System - Zuverlässigkeit und Integration“ 15 20 25 30 35 40 45 50 55 60 65 70SS012006003600 °C 700 °C 500 °C400 °C300 °Cas dep.  XRD - Intensity in a.u.2 in deg.200 300 400 500 600 700 800480590700 °C 600 °C 500 °C 400 °C 300 °Cas dep.  Raman - Intensity in a.u.Raman shift in cm-10 20 40 60 80 100 120 140 160 180 200 220 24001020304050  Vol. capacity in µAh/cm2µmCycle number Charge Dischargeas dep. 7 Pa0 5 10 15 20 25 302030405060708090100  Vol. capacity in µAh/cm2µmCycle number Charge Discharge7 Pa / 600 °C, 1h, Ar:O2 (80:20)15 20 25 30 35 40 45 50 55 60 65Si110018017009012006011015014003 20 Pa10 Pa7 Pa2 Pa4 Pa0.5 Pa2 in deg.p = 0.2 PaLi-Ni-Mn-Co-O thin film cathodes have been deposited onto stainless steel substrates by a non-reactive r.f. magnetron sputtering process from a Lithium-rich Li1.11(Ni0.37Mn0.19Co0.33)O1.77 target in a pure Argon atmosphere. The target power was 100 W and the deposition pressure 7 Pa. Coating thickness was about 1 µm. In order to induce a transition of the crystalline films from a disordered to an ordered layered structure the films were post heat treated between 300 °C and 700 °C for one hour at 10 mPa in  Argon / Oxygen (80 : 20).   R.f. magnetron  sputtering: X-Ray diffraction as deposited 𝜎′(𝜔 ≈ 0) = 𝜎𝑑𝑐 =𝑑𝑆∙𝑅𝑒𝑙 + 𝑅𝑖𝑜𝑛𝑅𝑒𝑙𝑅𝑖𝑜𝑛=𝑑𝑆∙1𝑅𝑔𝑒𝑠 𝜎′′ 𝜔 = 𝜔 ∙ 𝐶 ∙𝑑𝑆 Rel C Rion Rges 0 10 20 30 40 50 60 70 80 9005101520253035Scan : 5 Hz to 13 MHz (100 mV)Nyquist-Plot20°C (replicated)20°C30°C40°C50°C60°C  Imaginary Part (-Z'') in kReal Part (Z') in k 70°C1𝑍=1𝑅𝑖𝑜𝑛+1𝑅𝑒𝑙+ 𝑖𝜔𝐶 X-Ray diffraction heat treated films (7 Pa) Raman spectroscopy heat treated films (7 Pa)  XRD - Intensity in a.u. SEM and AFM measurements of as dep. films deposited at 7 Pa SEM and AFM measurements of heat treated films at 600 °C ICP-OES and CGHE analysis (before annealing) AC-impedance spectroscopy of heat treated film at 600 °C Nyquist plot: It is possible to calculate the specific conductivity of the thin film with the intersection of the semicircle at small frequencies (10 Hz) and the real part axis of the Nyquist-plot. Arrhenius-Plot: The measurements depending on the temperature allows the determination of the activation energy Ea of the ionic hopping mechanism.  Galvanostatic cycling of as dep. films deposited at 7 Pa Galvanostatic cycling of heat treated films at 600 °C - Li-Ni-Mn-Co-O thin films were successfully deposited on stainless steel with different compositions and microstructures. - In crystalline as dep. films at 7 Pa a transition has been successfully induce of from a disordered to an ordered layered structure by post deposition heat treatment.  - As deposited and heat treated films at 600 °C are battery active. - Heat treated thin film cathodes show a lower loss of discharge capacity at first cycles. Film deposition Heat treatment of selected film (7 Pa)    Pressure variation Galvanostatic cycling Ar-working gas pressure in Pa Ordered layered structure NMC A1g Eg disordered layered structure NMC µm µm 800 nm 800 nm Ordered layered structure NMC T [°C] σdc [Scm-1] 20 1,72*10-8 30 2,39*10-8 40 3,05*10-8 50 3,82*10-8 60 5,18*10-8 70 6,30*10-8 Film thickness d ~ U,I,φ      Gold Pads Thin film cathode l  pThin fil  cathode material 0.0029 0.0030 0.0031 0.0032 0.0033 0.0034-13.0-12.5-12.0-11.5-11.0-10.5-10.0  ln(dcT) in Scm-1K1/T in 1/KArrhenius-PlotEA = 0,28 ± 0,09 eV ln(𝜎𝑑𝑐 ∗ T) = ln 𝐾 −𝐸𝐴𝑘𝑏∗1𝑇 Assumed Model: RA = 32 nm RA = 6 nm Cycled between 3 V - 4.3 V with 10 µA in LiPF6 in EC/DMC as Electrolyte against Li Cycled between 3 V - 4.3 V with 30 µA in LiPF6 in EC/DMC as Electrolyte against Li  

Microstructural and electrochemical comparison of as deposited and heat treated Li-Ni-Mn-Co-O thin film cathodes for Lithium-ion batteries

https://publikationen.bibliothek.kit.edu/220102335/3816921

Microstructural and electrochemical comparison of as deposited and heat treated Li-Ni-Mn-Co-O thin film cathodes for Lithium-ion batteries

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