Configurational Entropy of Lithium Manganese Oxide and Related Materials, LiCr[sub y]Mn[sub 2−y]O[sub 4] (y=0, 0.3)

Kobayashi, Yo; Mita, Yuichi; Seki, Shiro; Ohno, Yasutaka; Miyashiro, Hajime; Nakayama, Masanobu; Wakihara, Masataka

doi:10.1149/1.2799069

Cited by 17 publications

(27 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On the other hand, exothermic and endothermic peaks were observed at capacities between 25 and 110 mAhg −1 as shown in Figure 6c. The characteristic thermal profiles have been explained by the partial ordering of lithium ions in the spinel structure, 9 and a similar spinel-like heat flow characteristic was obtained here as shown in Figure 6b. In detail, the exothermic peak at 20 mAhg −1 in Figure 6b was not observed for the heat flow of the cathode in Figure 5c.…”

Section: Resultssupporting

confidence: 80%

Decrease in Capacity in Mn-Based/Graphite Commercial Lithium-Ion Batteries

Kobayashi

Shono

et al. 2013

J. Electrochem. Soc.

Self Cite

View full text Add to dashboard Cite

A precise and simple temperature measurement technique during charge and discharge is applied to 5 Ah Al-laminated lithium-ion batteries (LiMn 2 O 4 /LiNi 0.8 Co 0.15 Al 0.05 O 2 cathode and graphite anode) using a quasi-adiabatic cell holder. The obtained temperature profiles are described in terms of the reactions of the anode and cathode. This technique is applied to a cycled cell, and the capacity fading mechanism is also indicated by the temperature profiles. From the comparison between the cell temperature profiles and the reaction heat flows of the half cells in each electrode obtained by an isothermal microcalorimeter, we find that the capacity fading of the cycled cell can be derived from the capacity fading of the cathode and also from the upward shift in the operated state of charge (SOC) of the cathode in the cell. The latter shift is derived from the irreversible loss of lithium at the anode, and it leads to the misalignment of the cathode and anode operation windows. The proposed temperature measurement technique has the potential to be applied to various types of large lithium-ion batteries during operation, thus providing a new approach to analyzing the degradation of lithium-ion batteries.The applications of lithium-ion batteries are now being extended from mobile use to hybrid, plug-in hybrid, and electric vehicles, and various stationary uses. In these systems, the lithium-ion batteries are required to have a larger capacity and a longer lifetime than those for mobile use. Determination of the degradation factor in cells is becoming essential for improving the lifetime of batteries. Postanalysis, such as analysis of the electrode structure, electrolyte composition, and solid electrolyte interface (SEI), is a conventional tool used to determine the degradation of materials in cells. However, a large number of samples are needed to determine the degradation process during the operation. Nondestructive analyzes, such as capacity retention, power fading, and AC impedance analysis, are other approaches to determining the degradation process during cell operation. However, using these approaches it is not easy to find a convincing relationship between capacity fading and the degradation of the materials and/or misalignment of the electrode-capacity window in the cathode and anode materials in a cell.Electrochemical calorimetry is a useful nondestructive approach to determining electrode reactions during the charge and discharge of lithium-ion cells. [1][2][3][4][5] This approach enables the reactions at each electrode to be separated by comparing the heat flow profiles of half cells. We previously reported its application to prismatic [graphite/LiMn 2 O 4 ] 2 and cylindrical 18650-type [graphite/LiCoO 2 ] 5 cells, determination of the thermal behavior of graphite and LiCoO 2 , and analysis of the degradation from heat flow profiles. However, the conductive-type microcalorimeter that was used had a size limitation (<50 mmφ), meaning that we could not apply it to larger cells. Therefore, a more versati...

show abstract

Section: Resultssupporting

confidence: 80%

Decrease in Capacity in Mn-Based/Graphite Commercial Lithium-Ion Batteries

Kobayashi

Shono

et al. 2013

J. Electrochem. Soc.

Self Cite

View full text Add to dashboard Cite

show abstract

“…In particular, by examining Figure 7b, the difference in the amplitudes of the two peaks for the same defect content y becomes more obvious than looking only at the changes with respect to ∂S/∂x. Asymmetries in the peak magnitudes have been observed experimentally in Li x Mn 2 O 4 [13], overlithiated Li 1+x Mn 2-x O 4 [14] and also Li x M y Mn 2-y O 4 [21,25] although not previously remarked upon. The origin of the peak magnitude difference can be observed in Figure 8 in Figure 8b.…”

Section: Intercalation In LI X Mn 2 Omentioning

confidence: 54%

“…To better understand such profiles and enable more definitive structural assessments from them, a more quantitative understanding of the relationship between the peak amplitudes and the structure is needed. In the case of Li x Mn 2 O 4 spinel, which is the focus of the present work, previous in-situ nuclear magnetic resonance (NMR) and X-ray diffraction (XRD) have revealed some contradictory results regarding phase transitions in the Li structure [14,[39][40][41]; electrochemical thermodynamic measurements have revealed additional information about the phase diagram at room temperature and have added more insight into the two phase coexistence region [14,18,21]. The two peaks observed in the entropy profiles of this electrode are generally considered to arise from the formation of an ordered phase, Li 0.5 Mn 2 O 4 at intermediate state of charge, and a transition to a disordered phase at high and low intercalation in the range 0 < x < 1 [18,[42][43][44].…”

Section: Introductionmentioning

confidence: 86%

“…The entropy change during Li intercalation in graphite was also investigated theoretically by Leiva et al [32] [33]. Later work also investigated the entropy change in cathode materials, including Li x CoO 2 [8,9,15,20], undoped Li x Mn 2 O 4 spinel [13], Li x+δ Mn 2-δ O 4 [14], where δ represents an excess amount of Li substituted in the octahedral sites [34,35], Li x M y Mn 2-y O 4 [13,19,21,25], where M denotes a metal defect, and nickel manganese cobalt (NMC) based layered materials [24,36]. The cited studies have found that the features in these profiles arise from changes in the configurational entropy at the cathode upon (de-)intercalation, and hence the peaks and troughs observed correspond to structural, order/disorder, and other types of phase transitions [8,18,19,37,38].…”

Section: Introductionmentioning

confidence: 98%

“…There has been an interest in techniques based on thermodynamic measurements. One method that has been developed is generally known as entropy profiling [8,9,[12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. This technique is based on the principle that the partial molar entropy change is proportional to the temperature response of the open circuit potential (OCP) of a cell, by…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The influence of point defects on the entropy profiles of Lithium Ion Battery cathodes: a lattice-gas Monte Carlo study

Mercer

Finnigan

Kramer

et al. 2017

Electrochimica Acta

View full text Add to dashboard Cite

In-situ diagnostic tools have become established to as a means to understanding the aging processes that occur during charge/discharge cycles in Li-ion batteries (LIBs). One electrochemical thermodynamic technique that can be applied to this problem is known as entropy profiling. Entropy profiles are obtained by monitoring the variation in the open circuit potential as a function of temperature. The peaks in these profiles are related to phase transitions, such as order/disorder transitions, in the lattice. In battery aging studies of cathode materials, the peaks become suppressed but the mechanism by which this occurs is currently poorly understood. One suggested mechanism is the formation of point defects. Intentional modifications of LIB electrodes may also lead to the introduction of point defects. To gain quantitative understanding of the entropy profile changes that could be caused by point defects, we have performed Monte Carlo simulations on lattices of variable defect content. As a model cathode, we have chosen manganese spinel, which has a well-described order-disorder transition when it is half filled with Li. We assume, in the case of trivalent defect substitution (M=Cr,Co) that each defect M permanently pins one Li atom. This assumption is supported by Density Functional Theory (DFT) calculations. Assuming that the distribution of the pinned Li sites is completely random, we observe the same trend in the change in partial molar entropy with defect content as observed in experiment: the peak amplitudes become increasing suppressed as the defect fraction is increased. We also examine changes in the configurational entropy itself, rather than the entropy change, as a function of the defect fraction and analyse these results with respect to the ones expected for an ideal solid solution. We discuss the implications of the quantitative differences between some of the results obtained from the model and the experimentally observed ones.

show abstract

Electrochemical Stiffness Changes in Lithium Manganese Oxide Electrodes

Çapraz

Bassett

Gewirth

et al. 2016

Advanced Energy Materials

View full text Add to dashboard Cite

In situ strain and stress measurements are performed on composite electrodes to monitor potentialdependent stiffness changes in lithium manganese oxide (LiMn 2 O 4 ). Lithium insertion and removal results in asynchronous strain and stress generation in the electrode. Electrochemical stiffness changes are calculated by combining coordinated stress and strain measurements. The electrode experiences dramatic changes in electrochemical stiffness due to potential-dependent Li + ion intercalation mechanisms. The development of stress in the early stages of delithiation (at ca. 3.95 V) due to a kinetic barrier at the electrode surface gives rise to stiffness changes in the electrode. Strain generation due to phase transformations reduces stiffness in the electrode at 4.17 V during delithiation and at 4.11 V during lithiation. During lithiation, stress generation due to Coulombic repulsions between occupied and incoming Li + ions leads to stiffening of the electrode at 3.96 V. The electrode also experiences greater changes in stiffness during delithiation compared to lithiation. These changes in electrochemical stiffness provide insight into the interplay between mechanical and electrochemical properties which control electrode response to lithiation and delithiation.

show abstract

Configurational Entropy of Lithium Manganese Oxide and Related Materials, LiCr[sub y]Mn[sub 2−y]O[sub 4] (y=0, 0.3)

Cited by 17 publications

References 16 publications

Decrease in Capacity in Mn-Based/Graphite Commercial Lithium-Ion Batteries

Decrease in Capacity in Mn-Based/Graphite Commercial Lithium-Ion Batteries

The influence of point defects on the entropy profiles of Lithium Ion Battery cathodes: a lattice-gas Monte Carlo study

Electrochemical Stiffness Changes in Lithium Manganese Oxide Electrodes

Contact Info

Product

Resources

About