Three-dimensional investigation of cycling-induced microstructural changes in lithium-ion battery cathodes using focused ion beam/scanning electron microscopy

Liu, Hanshuo; Foster, Jamie M.; Gully, A.; Krachkovskiy, Sergey A.; Jiang, Meng; Wu, Yan; Yang, Xuelin; Protas, Bartosz; Goward, Gillian R.; Botton, Gianluigi A.

doi:10.1016/j.jpowsour.2015.11.108

Cited by 65 publications

(55 citation statements)

References 44 publications

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“…[22,25,34,45] Additional information about these electrodes can be found in previous papers that analyzed the homogeneity of the samples. [22,25,34,45] Additional information about these electrodes can be found in previous papers that analyzed the homogeneity of the samples.…”

Section: Electrode Morphologymentioning

confidence: 99%

“…Thus, below C*, the lower rate performance of B is likely due to poorer ionic wiring of the active mass due to the surface covering of the NMC particles by the CB + PVdF phase limiting the liquid electrolyte access and hindering lithium insertion, as shown by the larger polarization and lower capacity. Thus the difference in the rate performance can be attributed to improved electronic wiring of the active mass as a consequence of higher interconnectivity with the CB + PVdF mixture in F. [34] According to Gaberscek model, R electrode should scale inversely with the interconnectivity between the active mass and the CB network if the main limitation comes from step (II). This can be seen in the interconnectivity values (Figure 3d,e), 8% and 3% for NMC/ CB + PVdF, and 23% and 13% for LFP/CB + PVdF, in F and H, respectively.…”

Section: Major Role Of the Electronic Wiring (Active Mass/cb + Pvdf Imentioning

confidence: 99%

“…However, one disadvantage of XRCT is the difficulty of distinguishing the carbon additive and the binder mixture from the pore space due to the small particle size and the low X-ray attenuation difference of the carbon and binder mixture. [34] Moreover and surprisingly, attempts to correlate quantified 3D geometries with measured electrochemical power performance [19] or electrical transport properties [35] of same actual electrodes remain rare or modest. The combination of XRCT and FIB-SEM is then a method of choice for exhaustive multiscale description of the electrode 3D geometry.…”

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confidence: 99%

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Multiscale Morphological and Electrical Characterization of Charge Transport Limitations to the Power Performance of Positive Electrode Blends for Lithium‐Ion Batteries

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Etiemble

Douillard

et al. 2016

Advanced Energy Materials

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In this work, exhaustive characterizations of 3D geometries of LiNi1/3Mn1/3Co1/3O2 (NMC), LiFePO4 (LFP), and NMC/LFP blended electrodes are undertaken for rational interpretation of their measured electrical properties and electrochemical performance. X‐ray tomography and focused ion beam in combination with scanning electron microscopy tomography are used for a multiscale analysis of electrodes 3D geometries. Their multiscale electrical properties are measured by using broadband dielectric spectroscopy. Finally, discharge rate performance are measured and analyzed by simple, yet efficient methods. It allows us to discriminate between electronic and ionic wirings as the performance limiting factors, depending on the discharge rate. This approach is a unique exhaustive analysis of the experimental relationships between the electrochemical behavior, the transport properties within the electrode, and its 3D geometry.

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Section: Electrode Morphologymentioning

confidence: 99%

Section: Major Role Of the Electronic Wiring (Active Mass/cb + Pvdf Imentioning

confidence: 99%

mentioning

confidence: 99%

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Multiscale Morphological and Electrical Characterization of Charge Transport Limitations to the Power Performance of Positive Electrode Blends for Lithium‐Ion Batteries

Besnard

Etiemble

Douillard

et al. 2016

Advanced Energy Materials

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“…This could induce a detachment between binder and active particles along with cracks forming inside the secondary particles. 11,12 A number of strategies have been used to protect the positive electrode surface from parasitic reactions. These include the use of electrolyte additives, different salts, different solvents and electrode material coatings.…”

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confidence: 99%

Using the Charge-Discharge Cycling of Positive Electrode Symmetric Cells to Find Electrolyte/Electrode Combinations with Minimum Reactivity

Shen

Xiong

Ellis

et al. 2017

J. Electrochem. Soc.

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The effects of solvents, salts, electrolyte additives and surface coatings on LiNi 0.4 Mn 0.4 Co 0.2 O 2 (NMC442) or LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC622) have been probed using positive electrode Li-ion symmetric cells coupled with dV/dQ analysis. A robust symmetric cell design is presented which prevents hardware corrosion for over at least 800 hours of testing to 4.5 V vs. Li/Li + at 40 • C. Positive electrode symmetric cells using uncoated positive electrode materials and 1M LiPF 6 EC:EMC 3:7 or 1M LiPF 6 EMC electrolyte rapidly developed high impedance and showed poor capacity retention. However, if 1% pyridine boron trifluoride (PBF) was added to these electrolytes, cell performance was dramatically improved. Replacing LiPF 6 by LiBF 4 in the electrolytes above, with or without PBF, yielded positive electrode symmetric cells with good capacity retention. Two types of surface coatings were explored on NMC622 positive electrodes. Cells using surface-coated positive electrodes demonstrated better capacity retention for all electrolytes compared to cells without surface coatings. This work can be used as a guide by those attempting to find electrolyte/electrode pairs suitable for use in NMC/graphite cells that can operate with long lifetime to 4. 1-4 The energy density of NMC/graphite cells can be easily improved if the cells can be charged to higher potential, for example to 4.4 or 4.5 V at which point the positive electrode is at about 4.48 or 4.58 V vs. Li/Li + . However, charging NMC/graphite cells to such potentials normally leads to impedance growth and a reduction in cycle and calendar life. 5,6 Increasing the charging cutoff voltage to 4.40 V can cause some problems: 1) Parasitic reactions like electrolyte oxidation can create harmful products and damage the surface of the electrodes. 7,8 In addition, in some cases, thick SEI layers on the positive electrode can be created.2) The layered surface structure of NMC (R3m) can change into a spinel-like framework (Fd3m) and then to the disordered rocksalt structure (Fm3m). 9,10 This is thought to be one cause of impedance growth at the positive electrode.3) The unit cell volume of most NMC materials begins to contract rapidly, by about 4%, when the potential is raised above 4.4 V vs Li/Li + as the lithium content is decreased below about z = 0.25 in Li x Ni 1-y-z Mn y Co z O 2 . This could induce a detachment between binder and active particles along with cracks forming inside the secondary particles. 11,12A number of strategies have been used to protect the positive electrode surface from parasitic reactions. These include the use of electrolyte additives, different salts, different solvents and electrode material coatings. Some of these strategies will be used in the work here. For example, Petibon et al. and Ma et al. 13,14 showed that ethylene carbonate (EC)-free electrolytes, like 1M LiPF 6 in 95% ethyl methyl carbonate with 5% fluoroethylene carbonate was very effective in allowing NMC/graphite cells to operate to 4.4 V. EC-free electrolytes will be expl...

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“…As most anode and cathode materials are susceptible to moisture and have a porous structure, mechanical polishing cannot be used as the large-area cross-section sampling preparation method. Instead, ion-milling method using a cross-section polisher (CP) and a focused ion beam (FIB) can be used (Ebner et al, 2013;Indrikova et al, 2015;Liu et al, 2016;Otoyama et al, 2016). FIB is often useful in observing specific areas by finely controlling the Ga + ion source.…”

Section: Introductionmentioning

confidence: 99%

Alternative Sample Preparation Method for Large-Area Cross-Section View Observation of Lithium Ion Battery

Kim

Jeong

Cho

et al. 2017

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Drastic development of ubiquitous devices requires more advanced batteries with high specific capacitance and high rate capability. Large-area microstructure characterization across the stacks of cathode, electrolyte and anode might reveal the origin of the instability or degradation of batteries upon cycling charge. In this study, sample preparation methods to observe the cross-section view of the electrodes for battery in SEM and several imaging tips are reviewed. For an accurate evaluation of the microstructure, ion milling which flats the surface uniformly is recommended. Pros and cons of cross-section polishing (CP) with Ar ion and focused ion beam (FIB) with Ga ion were compared. Additionally, a modified but new cross-section milling technique utilizing precision ion polishing system (PIPS) which can be an alternative method of CP is developed. This simple approach will make the researchers have more chances to prepare decent large-area cross-section electrode for batteries.

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Three-dimensional investigation of cycling-induced microstructural changes in lithium-ion battery cathodes using focused ion beam/scanning electron microscopy

Cited by 65 publications

References 44 publications

Multiscale Morphological and Electrical Characterization of Charge Transport Limitations to the Power Performance of Positive Electrode Blends for Lithium‐Ion Batteries

Multiscale Morphological and Electrical Characterization of Charge Transport Limitations to the Power Performance of Positive Electrode Blends for Lithium‐Ion Batteries

Using the Charge-Discharge Cycling of Positive Electrode Symmetric Cells to Find Electrolyte/Electrode Combinations with Minimum Reactivity

Alternative Sample Preparation Method for Large-Area Cross-Section View Observation of Lithium Ion Battery

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