Bhaskar, Aiswarya

Ehrenberg, Helmut

Kiziltas-Yavuz, Nilüfer

Knapp, Michael

Nikolowski, Kristian

Yavuz, Murat

DESY Publication Database

In situ PDF Experiments during Electrochemical Cycling of Cathode Materials for Li-ion Batteries

Yavuz, M.

Yavuz, N. K.

Knapp, M.

Bhaskar, A.

Nikolowski, K.

Ehrenberg, H.

KITopen

KIT – University of the State of Baden-Wuerttemberg and National Research Center of the Helmholtz Association         The Pair Distribution Function (PDF)/ Total scattering method is used to obtain information about the structural arrangement and about the disorder or local ordering that occurs due to (de)intercalation of lithium, which is correlated to degradation and fatigue in Li-ion battery materials. The PDF analysis/Total scattering technique, gives information about the local atomic arrangement in materials as well as the long range (average) structure. It mainly gives the probability of finding any two atoms at given distance “r” and it can be considered as a bond length distribution.         In situ investigations are of crucial importance to elucidate the processes during charging and discharging, because ex-situ studies can give unsatisfying or even misleading information due to relaxation phenomena [1,2]. The aim of this research is to show the applicability of in situ PDF measurements on a standard LiMn2O4 spinel, which is an excellent candidate as cathode material in Li-ion batteries, during electrochemical cycling.  In situ PDF Experiments during Electrochemical Cycling of Cathode Materials for Li-ion Batteries X-ray diffraction experiments were carried out at the High Resolution Powder Diffraction beamline (P02.1) at PETRA-III, DESY, using X-rays with an energy of 60 keV (λ=0.20726 Å). The 2D diffraction patterns of LiMn2O4 sample in an in situ cell are recorded on a flat panel detector (Perkin Elmer). The sample-detector distance was approximately 400mm. The max. Q-value was about 24 Å-1. M. Yavuz*1,2, N. K. Yavuz2, M. Knapp1,2, A. Bhaskar2, K. Nikolowski1,2, H. Ehrenberg1,2 1Helmholtz Institute Ulm (HIU) Electrochemical Energy Storage,  2Institute for Applied Materials-Energy Storage Systems (IAM-ESS),  Karlsruhe Institute of Technology (KIT), Herman-von-Helmholtz Platz 1,  76344 Eggenstein-Leopoldshafen, Germany - It is possible to subtract the background/container from XRD pattern.  - For PDF refinements, Li-contents (x) were obtained from electrochemical measurements. - In situ PDF analysis during electrochemcial cycling gives the details about structural and chemical transformations. - All refinements were implemented with cubic main phase and tetragonal impurity phase.  - Refinement of selected parameters with symmetry constraints. Energy Storage Systems (ESS) 100 μm glass window contact spring sealing ring insulating PTFE ring current collector 300μm glassy carbon window  working electrode seperator counter electrode Herklotz et al., J. Appl. Cryst. (2013) 46, 1117-1127 synchrotron beam 1 2 3 4 5 9 8 7 6 XRD patterns of in situ LiMn2O4 during electrochemical cycling 3 V 4.9 V 2.6 V 1.3 V x (Li) =1.3 charge C/2 discharge C/2 XRD In situ cell holder  Background ; -300µm glassy carbon window  -seperators (whatman glass microfibre) -electrolyte (1M LiPF6 in EC:DMC 1:1 )  -lithium foil -100 µm glass window XRD pattern of in situ LiMn2O4 and background 3 V 4.9 V 2.6 V 1.3 V PDF PDFs of in situ LiMn2O4 during electrochemical cycling Experimental Details Results Overview  of insitu cell Introduction References [1] C. Baehtz, Th. Buhrmester, N.N. Bramnik, K. Nikolowski, H. Ehrenberg, Solid State Ionics 176 (2005) 1647 – 1652. [2] M. M. Thackeray, Prog. Solid State Chem. 25 (1997) 1-71.  *murat.yavuz@kit.edu Mn-O distances vs. Li-content  Cell parameters vs. Li-content 0.00 0.25 0.50 0.75 1.00 1.25 1.501.52.02.53.03.54.04.55.0  Ewe vs.Li/Li+ (V)Li-content (x)chargingdischargingVoltage vs. Li-content of LiMn2O4 0.25 0.50 0.75 1.00 1.250102030405060708090100dischargingMn3O4   Li-content (x)Phase Fraction (%)LiMn2O4dischargingPhase Fraction vs. Li-content 0.2 0.4 0.6 0.8 1.0 1.28.058.108.158.208.25 <---high lithiated--->dischargingLi2Mn2O4 a parameterLi2Mn2O4 c parameterLiMn2O4Mn3O4 a parameterMn3O4 c parametera parameter (LiMn2O4) (Å) Li-content (x)LiMn 2O 4charging5678910 cell parameter (Å)(Mn3O4 and Li 2Mn2O4)0.2 0.4 0.6 0.8 1.0 1.21.881.901.921.941.96chargingdischargingLi-content (x)  Mn-O (Å)dischargingLiMn2O4Conclusion 

In situ PDF experiments during electrochemical cycling of cathode materials for Li-ion batteries

DESY

https://publikationen.bibliothek.kit.edu/220092757/3816361

In situ PDF Experiments during Electrochemical Cycling of Cathode Materials for Li-ion Batteries

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