Electron Microscopy Study of the LiFePO[sub 4] to FePO[sub 4] Phase Transition

Chen, Guoying; Song, Xiangyun; Richardson, Thomas J.

doi:10.1149/1.2192695

Cited by 571 publications

(766 citation statements)

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“…Understanding the Li insertion/extraction mechanism at this interphase boundary is essential to understanding the electrochemical behavior of LFP. [36][37][38][39] Figure 2 HAADF-STEM images of Li-excess layered materials (a) at the pristine state and (b) after 10 cycles. 27 (c, d) EELS comparison of the particle surface and bulk for the pristine and cycled materials.…”

Section: Electrode Materialsmentioning

confidence: 99%

Advanced analytical electron microscopy for lithium-ion batteries

Qian

et al. 2015

NPG Asia Mater

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Lithium-ion batteries are a leading candidate for electric vehicle and smart grid applications. However, further optimizations of the energy/power density, coulombic efficiency and cycle life are still needed, and this requires a thorough understanding of the dynamic evolution of each component and their synergistic behaviors during battery operation. With the capability of resolving the structure and chemistry at an atomic resolution, advanced analytical transmission electron microscopy (AEM) is an ideal technique for this task. The present review paper focuses on recent contributions of this important technique to the fundamental understanding of the electrochemical processes of battery materials. A detailed review of both static (ex situ) and real-time (in situ) studies will be given, and issues that still need to be addressed will be discussed. NPG Asia Materials (2015) 7, e193; doi:10.1038/am.2015.50; published online 26 June 2015 INTRODUCTIONTo implement the commercialization of lithium-ion batteries in electric vehicles and smart grid systems, further improvements are required, especially with respect to the energy/power density, coulombic efficiency and cycle life. These parameters primarily depend on the diffusion of lithium-metal ions, electron transport, structure and chemical dynamics of the electrode/electrolyte materials, among others. During electrochemical cycling, significant changes in the material structure and elemental distributions occur, including ion relocation, lattice expansion/contraction, phase transition and structure/surface reconstruction. These changes could substantially influence ion and electron transport and affect the performance of the entire battery system. Understanding the structure-property relationships for each component and their synergistic behaviors during electrochemical processes is, therefore, essential for the design of new battery materials and the optimization of existing systems.Although many analysis techniques (for example, X-ray diffraction, X-ray absorption spectroscopy, neutron diffraction, nuclear magnetic resonance and so on) have been employed for such studies, most of them can acquire only spatially averaged information. Nevertheless, the structural and chemical evolution of battery materials upon electrochemical cycling can often be linked to specific nanofeatures, such as defects, interfaces and surfaces. As a result, techniques based on analytical transmission electron microscopy (AEM) are ideal tools to study these issues. The capability of AEM to precisely probe the structural/chemical evolutions at an ultrahigh spatial resolution frequently provides insight that cannot be obtained directly using macroscopic characterization methods.

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Section: Electrode Materialsmentioning

confidence: 99%

Advanced analytical electron microscopy for lithium-ion batteries

Qian

et al. 2015

NPG Asia Mater

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“…14 (and the corresponding batch of LiFeP04, see above Jhe samples, consistent with previous TEM results. 15 …”

Section: Xrd Phase Analysis Phemical Oxidation Of Lifep04 Crystals Pmentioning

confidence: 99%

“…Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) studies showed that the interfaces are in the (010) plane, which suggests that phase separation of the high temperature solid solutions proceeds by migration of lithium ions within the tunnels aligned with the 6-axis, thereby producing stacked layers of different compositions with phase boundaries in the ac plane. 15 In contrast, in the partially oxidized but unheated two-phase xLiFeP04/(l-x)FeP04 crystals, the end members are located in stripes alternating along the a direction with phase boundaries in the be plane. 15 Magic angle spinning nuclear magnetic resonance (MAS NMR) has proven to be a very useful technique to study short range ordering schemes that are not detectable by diffraction techniques in positive electrode materials 16 such as LiMn2C»4- 17 " 21 and LiMCV type (M=Mn 22 ' 23 , Co 24 and/or Ni 25 " 32 ) phases, both in pristine and in charged/discharged samples.…”

Section: Introductionmentioning

confidence: 97%

“…15 In contrast, in the partially oxidized but unheated two-phase xLiFeP04/(l-x)FeP04 crystals, the end members are located in stripes alternating along the a direction with phase boundaries in the be plane. 15 Magic angle spinning nuclear magnetic resonance (MAS NMR) has proven to be a very useful technique to study short range ordering schemes that are not detectable by diffraction techniques in positive electrode materials 16 such as LiMn2C»4- 17 " 21 and LiMCV type (M=Mn 22 ' 23 , Co 24 and/or Ni 25 " 32 ) phases, both in pristine and in charged/discharged samples. When experiments at different temperatures are combined, additional information regarding the diffusion of lithium and/or electron hopping can also be obtained.f ' ' ' ] Since the intermediate Li x FeP04 phases necessarily contain lithium vacancies and mixed Fe /Fe states, ' Li and P NMR experiments were conducted in this study in order to search for vacancy/charge ordering and enhanced ion/electron mobility in these phases.…”

Section: Introductionmentioning

confidence: 97%

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MAS NMR Study of the Metastable Solid Solutions Found in the LiFePO₄/FePO₄ System

et al. 2010

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6 ' 7 Li and 3I P NMR experiments were conducted on a series of single-or twophase samples in the LiFePCvFePCM system with different overall lithium contents, and containing the two end-members and/or two metastable solid solution phases, Lio.6FeP04 or Lio.34FeP04. These experiments were carried out at different temperatures in order to search for vacancy/charge ordering and ion/electron mobility in the metastable phases.Evidence for Li + -Fe 2+ interactions was observed for both Lio.6FeP04 and Lio.34FePC>4.The strength of this interaction leads to the formation of LiFePCvlike clusters in the latter, as shown by the room temperature data. Different motional processes are proposed to exist as the temperature is increased and various scenarios are discussed. While concerted lithium-electron hopping and/or correlations explains the data below 125°C, evidence for some uncorrelated motion is found at higher temperatures, together with the onset of phase mixing.2

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“…Recent work has significantly improved the rate capability of this material. [52,53] On the other hand, silicate compounds and other compounds have recently attracted a lot of interest as cathode materials. When two Li atoms are extracted from the structure, the Li 2 MSiO 4 cathode (M = Mn, Fe, Co and Ni) can exhibit a high theoretical specific capacity of ∼330 mAh g -1 (Li 2 FeSiO 4 ).…”

Section: Poly-anion Compoundsmentioning

confidence: 99%

Li‐Ion Batteries and Beyond: Future Design Challenges

Hwa

Cairns

2015

Encyclopedia of Inorganic and Bioinorganic Chemistry

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Light metals have been widely used as electrode materials for batteries owing to their low standard redox potential, their low equivalent weight, large specific capacity, and great abundance. Both primary and secondary cells including light metals as electrode material have influenced all aspects of our lives, e.g., electrically operated toys, power tools, and portable electronics such as cell phones, smart pads, and laptop computers. Among all battery systems, rechargeable lithium (Li) ion cells have been used most widely in recent years owing to their high specific power, high energy density, and ambient temperature operation. However, Li‐ion cells are facing difficult challenges in satisfying the emerging market for advanced applications demanding high‐performance rechargeable batteries for applications such as electric vehicles, high‐performance portable electronics, and large‐scale electrical energy storage systems. Unfortunately, current Li‐ion cells cannot satisfy demands such as low cost, much improved safety, larger energy density, faster charge/discharge rates, and longer service life, so intensive effort is necessary to develop the next generation of cells. In this article, the limitations of current Li‐ion cells and various advanced materials for each component of the Li‐ion cell, in addition to other promising candidates for cells beyond Li ion, such as the Li/S cell and Na‐ and Mg‐based rechargeable cells, and metal/air cells are discussed.

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Electron Microscopy Study of the LiFePO[sub 4] to FePO[sub 4] Phase Transition

Cited by 571 publications

References 18 publications

Advanced analytical electron microscopy for lithium-ion batteries

Advanced analytical electron microscopy for lithium-ion batteries

MAS NMR Study of the Metastable Solid Solutions Found in the LiFePO₄/FePO₄ System

Li‐Ion Batteries and Beyond: Future Design Challenges

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Electron Microscopy Study of the LiFePO[sub 4] to FePO[sub 4] Phase Transition

Cited by 571 publications

References 18 publications

Advanced analytical electron microscopy for lithium-ion batteries

Advanced analytical electron microscopy for lithium-ion batteries

MAS NMR Study of the Metastable Solid Solutions Found in the LiFePO4/FePO4 System

Li‐Ion Batteries and Beyond: Future Design Challenges

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MAS NMR Study of the Metastable Solid Solutions Found in the LiFePO₄/FePO₄ System