Structural Evolution of Li x Mn2 O 4 in Lithium‐Ion Battery Cells Measured In Situ Using Synchrotron X‐Ray Diffraction Techniques

Abstract

We describe synchroton based X-ray diffraction techniques and issues related to in situ studies of intercalation processes in battery electrodes. We then demonstrate the utility of this technique, through a study of two batches of LiMn2O4 cathode materials. The structural evolution of these spinel materials was monitored in situ during the initial charge of these electrodes in actual battery cells. Significant differences were observed in the two batches, particularly in the intercalation range of x = 0.45 to 0.20. The first-order structural transitions in this region indicated coexistence of two cubic phases in the batch 2 material, whereas the batch 1 material showed suppressed two-phase coexistence. Batch 2 cells also indicated structural evolution in the low-potential region below 3.0 V in contrast to the batch 1 material. Differences in structural evolution between batches of LiMn2O, could have important ramifications in their cycle life and stability characteristics. 466 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 134.48.29.181 Downloaded on 2014-11-03 to IP 10 x-ray photon energy (keY) 100 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 134.48.29.181 Downloaded on 2014-11-03 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 134.48.29.181 Downloaded on 2014-11-03 to IP ABSTRACTChemical reactions taking place at elevated temperatures in a polymer-bonded lithiated carbon anode were studied by differential scanning calorimetry. The influences of parameters such as degree of intercalation, number of cycles, specific surface area, and chemical nature of the binder were elucidated. It was clearly established that the first reaction taking place at ca. 120-140 °C was the transformation of the passivation layer products into lithium carbonate, and that lithiated carbon reacted with the molten binder via dehydrofluorination only at T> 300 °C. Both reactions strongly depend on the specific surface area of the electrodes and the degree of lithiation.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 134.48.29.181 Downloaded on 2014-11-03 to IP

Synchrotron‐Based X‐ray Absorption Fine Structures, X‐ray Diffraction, and X‐ray Microscopy Techniques Applied in the Study of Lithium Secondary Batteries

“…In situ and operando SXRD has been intensively carried out to study the electrochemical reaction mechanism of insertion, conversion, and alloy-type electrode materials with a focus on tracking structural and phase evolution and the formation of defects and strain in lithium-ion, [141][142][143][144][145][146][147][148][149] Li-S/Se, [28,98,150,151] and Li-O 2 [152][153][154] batteries with cycling and operation at various temperatures.…”

“…Shortly after, several electrode materials were studied using in situ/operando SXRD technique to track the lattice parameters and phase variation during the cycling, showing the evidence of the electrochemical reaction mechanism, such as layered and spinel oxides. [144,156,157] Based on the collection of real-time electrochemical cycling data, intermediate phases were found to form during cycling reaction. While monoclinic Li-rich Li y VO 2 phase has been found to be formed during the cycling of VO 2 , some solid-solution intermediates have been confirmed during the electrochemical reaction LiNi 0.5 Mn 1.5 O 4 .…”

Three‐Dimensional Microstructural Characterization of Lithium Manganese Oxide with Atom Probe Tomography

“…Examples are X-ray diffractions tudies on structural changes in lithium manganese oxide (LMO)i nduced by Li (de)intercalation [1][2][3][4][5][6] and on the influence of dopants in LMO on the cycling performance [7] in addition to electrochemical impedances pectroscopy studies on the Li-insertion process in Li x Mn 2 O 4 to develop an atomic modelf or Li insertion. [8,9] Am ore detailed understanding of the processes determining battery performance requires the investigation of the individual battery components and their interaction.…”

Atomic‐Scale Structure Evolution in a Quasi‐Equilibrated Electrochemical Process of Electrode Materials for Rechargeable Batteries

“…Ideally, the insertion and deinsertion processes of lithium should leave the host structure intact. In practice, however, the large variation in lithium content within electrodes during discharge and charge cycles is often accompanied by a diverse range of structural changes, such as lattice expansion or contraction, migration of transition metal (TM) ions, Jahn–Teller distortion, order–disorder transition, two‐phase reaction, phase separation, and surface reconstruction . Such changes occur locally at atomic scale and unavoidably impose significant influence on lithium diffusion, electron transport, and structural integrity of electrodes at mesoscopic and macroscopic levels, which to a great extent determine the performance and lifetime of LIBs.…”