Low-temperature synthesized Li4Mn5O12-like cathode with hybrid cation- and anion-redox capacities

Liu, Yang; Liu, Guang; Xu, Hui; Zheng, Yuheng; Huang, Yunhui; Li, Sa; Li, Ju

doi:10.1039/c9cc02006c

Cited by 26 publications

(28 citation statements)

References 33 publications

(36 reference statements)

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“…Therefore, the Mn 4+ /Mn 3+ cation‐redox capacity (proportional to the total length of the dashed line passing through the spinel composition in Figure 5) decreases dramatically with increasing Li‐richness x . This means if a Li‐rich spinel (an extreme case would be x = 1/3 or Li 4 Mn 5 O 12 where 100% of Mn valence is 4+) can still give significant charging capacity experimentally, [ 31 ] then part of this capacity must originate from oxygen redox, or HACR activities. [ 32 ] On the other hand, the increase of average Mn valence broadens the cubic spinel regime of Li 1+ x Mn 2− x O 4 before transforming to tetragonal rocksalt phase, and also increases the average Mn valance to (6− x )/(2− x ) in fully lithiated product Li 2+ x Mn 2− x O 4 .…”

Section: Fundamentals Of Limn2o4 and Its Derivativesmentioning

confidence: 99%

“…However, in Li‐rich spinel such as Li 4 Mn 5 O 12 where Li substitute some of the Mn, TMO hybridization becomes weaker, upshifting the O‐orbital energy level and rendering anion redox accessible at a lower voltage. Liu et al [ 31 ] recently reported HACR [ 32 ] activities in a Li‐rich spinel with nominal composition close to Li 4 Mn 5 O 12 , where oxygen anion‐redox ( m , a ‐contribution) and TM cation‐redox ( p , c ‐contribution) reactions could give a theoretical capacity of 243.9 mAh g −1 (illustrated in Figure 9 ). Some oxygen loss in the initial formation cycles could reduce the average valence of Mn, and cause increasing proportion of cation redox in later cycles, but reversible oxygen anion redox are likely still present.…”

Section: Spinel Structure As Degradation Product and Structural Stabimentioning

confidence: 99%

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Lithium Manganese Spinel Cathodes for Lithium‐Ion Batteries

Huang

Dong

et al. 2020

Advanced Energy Materials

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Spinel LiMn2O4, whose electrochemical activity was first reported by Prof. John B. Goodenough's group at Oxford in 1983, is an important cathode material for lithium‐ion batteries that has attracted continuous academic and industrial interest. It is cheap and environmentally friendly, and has excellent rate performance with 3D Li+ diffusion channels. However, it suffers from severe degradation, especially under extreme voltages and during high‐temperature operation. Here, the current understanding and future trends of the spinel cathode and its derivatives with cubic lattice symmetry (LiNi0.5Mn1.5O4 that shows high‐voltage stability, and Li‐rich spinels that show reversible hybrid anion‐ and cation‐redox activities) are discussed. Special attention is given to the degradation mechanisms and further development of spinel cathodes, as well as concepts of utilizing the cubic spinel structure to stabilize high‐capacity layered cathodes and as robust framework for high‐rate electrodes. “Good spinel” surface phases like LiNi0.5Mn1.5O4 are distinguished from “bad spinel” surface phases like Mn3O4.

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Section: Fundamentals Of Limn2o4 and Its Derivativesmentioning

confidence: 99%

Section: Spinel Structure As Degradation Product and Structural Stabimentioning

confidence: 99%

Lithium Manganese Spinel Cathodes for Lithium‐Ion Batteries

Huang

Dong

et al. 2020

Advanced Energy Materials

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233

169

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“…In the former case, electrochemical cycling is accompanied by voltage fade and the gradual migration of cations from one layer to the next, 20 while lithium and oxygen loss from Li4Mn5O12 (2Li2O•5MnO2) results in an electrochemical profile that increasingly resembles that of a Li-rich Li1+xMn2-xO4 spinel electrode (0<x<0.33) with a composition between LiMn2O4 and Li4Mn5O12. 21 In contrast, LT-LiMn0.5Ni0.5O2, which is not lithium-rich, has an electrochemical profile that is notably more tolerant and stable to repeated charging to 5 V (Fig. 3a) illustrating the superior robustness of the partially-disordered lithiated-spinel electrode.…”

Section: Resultsmentioning

confidence: 97%

LT-LiMn0.5Ni0.5O2: A Unique Co-Free Cathode for High Energy Li-Ion Cells

Shi

Gim

et al. 2021

Preprint

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A new Li-ion battery cathode, ‘LT-LiMn0.5Ni0.5O2’, where LT refers to its relatively low synthesis temperature (400 oC), has been identified. Electrochemical data indicate that Li/LT-LiMn0.5Ni0.5O2 cells operate between 5.0 and 2.5 V with good cycling stability, yielding a cathode capacity of 225 mAh/g. The electrochemical reactions occur in two distinct steps centered at ~3.75 V and ~4.7 V during charge, and at ~4.6 V and ~3.5 V during discharge. High-angle, annular-dark-field (HAADF) scanning-transmission electron microscopy (STEM) provide evidence that LT-LiMn0.5Ni0.5O2 consists of a unique, partially-disordered LiMn0.5Ni0.5O2 structure with predominant lithiated-spinel- and layered-like character. Structural analysis of LT-LiMn0.5Ni0.5O2 with synchrotron X-ray diffraction data shows, surprisingly, that lithiated-spinel and layered models with approximately 16% (~1/6) disorder between the lithium and manganese/nickel ions, yield an identical fit to the data, complicating the determination of the exact nature and level of disorder in each structural model. We believe that this is the first report of a Mn-stabilized, lithium-nickel-oxide spinel-related structure in which the redox reactions occur almost entirely on the nickel ions, with the likelihood that oxygen redox also contributes to some capacity above 4.7 V.

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“…(alternatively, 0.3Li2MnO3•0.7LiMn0.5Ni0.5O2) 20 and spinel Li4Mn5O12 21 , are charged repeatedly to potentials above 4.6 V, lithium is extracted with concomitant oxygen loss (net loss = Li2O). In the former case, electrochemical cycling is accompanied by voltage fade and the gradual migration of cations from one layer to the next, 20 while lithium and oxygen loss from Li4Mn5O12 (2Li2O•5MnO2) results in an electrochemical profile that increasingly resembles that of a Li-rich Li1+xMn2-xO4 spinel electrode (0<x<0.33) with a composition between LiMn2O4 and Li4Mn5O12.…”

Section: Figurementioning

confidence: 99%

LT-LiMn0.5Ni0.5O2: A Unique Co-Free Cathode for High Energy Li-Ion Cells

Shi

Gim

et al. 2021

Preprint

View full text Add to dashboard Cite

A new Li-ion battery cathode, 'LT-LiMn0.5Ni0.5O2', where LT refers to its relatively low synthesis temperature (400 °C), has been identified. Electrochemical data indicate that Li/LT-LiMn0.5Ni0.5O2 cells operate between 5.0 and 2.5 V with good cycling stability, yielding a cathode capacity of 225 mAh/g. The electrochemical reactions occur in two distinct steps centered at ~3.75 V and ~4.7 V during charge, and at ~4.6 V and ~3.5 V during discharge. High-angle, annulardark-field (HAADF) scanning-transmission electron microscopy (STEM) provide evidence that LT-LiMn0.5Ni0.5O2 consists of a unique, partially-disordered LiMn0.5Ni0.5O2 structure with predominant lithiated-spinel-and layered-like character. Structural analysis of LT-LiMn0.5Ni0.5O2 with synchrotron X-ray diffraction data shows, surprisingly, that lithiated-spinel and layered models with approximately 16% (~1/6) disorder between the lithium and manganese/nickel ions, yield an identical fit to the data, complicating the determination of the exact nature and level of disorder in each structural model. We believe that this is the first report of a Mn-stabilized, lithium-nickel-oxide spinel-related structure in which the redox reactions occur almost entirely on the nickel ions, with the likelihood that oxygen redox also contributes to some capacity above 4.7 V.

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Low-temperature synthesized Li₄Mn₅O₁₂-like cathode with hybrid cation- and anion-redox capacities

Abstract: A random Li4Mn5O12-like nanoparticulate cathode demonstrates a high reversible capacity (212 mA h g−1) with a hybrid cation-redox capacity (108 mA h g−1) and anion-redox capacity (103 mA h g−1).

Cited by 26 publications

References 33 publications

Lithium Manganese Spinel Cathodes for Lithium‐Ion Batteries

Lithium Manganese Spinel Cathodes for Lithium‐Ion Batteries

LT-LiMn0.5Ni0.5O2: A Unique Co-Free Cathode for High Energy Li-Ion Cells

LT-LiMn0.5Ni0.5O2: A Unique Co-Free Cathode for High Energy Li-Ion Cells

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