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Li-rich Li-Si alloy as a lithium-containing negative electrode material towards high energy lithium-ion batteries.

Iwamura S, Nishihara H, Ono Y, Morito H, Yamane H, Nara H, Osaka T, Kyotani T - Sci Rep (2015)

Bottom Line: Since Li-Si is free from severe constriction/expansion upon delithiation/lithiation, it shows much better cyclability than Si.The feasibility of the Li-Si alloy is further examined by constructing a full-cell together with a lithium-free positive electrode.Though Li-Si alloy is too active to be mixed with binder polymers, the coating with carbon-black powder by physical mixing is found to prevent the undesirable reactions of Li-Si alloy with binder polymers, and thus enables the construction of a more practical electrochemical cell.

View Article: PubMed Central - PubMed

Affiliation: 1] Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan [2] Division of Chemical Process Engineering, Graduate School of Engineering, Hokkaido University, N13W8 Kita-ku, Sapporo 060-8628, Japan.

ABSTRACT
Lithium-ion batteries (LIBs) are generally constructed by lithium-including positive electrode materials, such as LiCoO2, and lithium-free negative electrode materials, such as graphite. Recently, lithium-free positive electrode materials, such as sulfur, are gathering great attention from their very high capacities, thereby significantly increasing the energy density of LIBs. Though the lithium-free materials need to be combined with lithium-containing negative electrode materials, the latter has not been well developed yet. In this work, the feasibility of Li-rich Li-Si alloy is examined as a lithium-containing negative electrode material. Li-rich Li-Si alloy is prepared by the melt-solidification of Li and Si metals with the composition of Li21Si5. By repeating delithiation/lithiation cycles, Li-Si particles turn into porous structure, whereas the original particle size remains unchanged. Since Li-Si is free from severe constriction/expansion upon delithiation/lithiation, it shows much better cyclability than Si. The feasibility of the Li-Si alloy is further examined by constructing a full-cell together with a lithium-free positive electrode. Though Li-Si alloy is too active to be mixed with binder polymers, the coating with carbon-black powder by physical mixing is found to prevent the undesirable reactions of Li-Si alloy with binder polymers, and thus enables the construction of a more practical electrochemical cell.

No MeSH data available.


Related in: MedlinePlus

The change of delithiation (open symbol) and lithiation (solid symbol) capacities of Li21Si5(0.2–2 μm) included in the Cu-pellet electrode or a sheet electrode.Current density is 50 mA g−1. Capacity is calculated based on (a) Li21Si5 and (b) the total electrode weight, respectively.
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f7: The change of delithiation (open symbol) and lithiation (solid symbol) capacities of Li21Si5(0.2–2 μm) included in the Cu-pellet electrode or a sheet electrode.Current density is 50 mA g−1. Capacity is calculated based on (a) Li21Si5 and (b) the total electrode weight, respectively.

Mentions: Fig. 7a shows the lithiation/delithiation capacities of a half-cell including the sheet electrode at 50 mA g−1. For comparison, the data of the Cu pellet electrode consisting of Li21Si5(0.2–2 μm) are also plotted. The pre-delithiation capacity of Li21Si5(0.2–2 μm) in the sheet electrode is 1219 mAh g−1, which is higher than the case of the Cu pellet electrode. Such high pre-delithiation capacity suggests that Li-Si alloy does not react with PTFE owing to the carbon-coating. The 1st lithiation/delithiation capacities are 1598/1457 mAh g−1, almost the same as the case of the Cu pellet electrode. In addition, the 10th lithiation/delithiation capacities (1220/1179 mAh g−1) are higher than those in the pellet electrode. Thus, Li21Si5(0.2–2 μm) embedded in the sheet electrode exhibits no less performance than the case of the Cu pellet electrode. Fig. 7b compares the capacities of these two electrodes, based on the weight of the total electrode weight. By preparing the lighter sheet electrode, the capacity based on the whole electrode weight can be greatly increased. Thus, carbon-coating is an effective way to avoid undesirable reactions between Li-Si alloy and the binder polymer, and would be crucial to utilize Li-rich Li-Si alloy as a lithium-containing negative electrode. This work has revealed the promising potential of Li-rich Li-Si alloy and demonstrated the method to prepare a light electrode sheet, based on the data obtained at early stage of charge/discharge. To achieve a long cycling life and to make the Li-Si alloy more practical, further improvement must be necessary, such as optimization of particle size, formation of composites with carbon, and/or appropriate surface oxidation38. We hope that this work could be a starting point of such future works.


Li-rich Li-Si alloy as a lithium-containing negative electrode material towards high energy lithium-ion batteries.

Iwamura S, Nishihara H, Ono Y, Morito H, Yamane H, Nara H, Osaka T, Kyotani T - Sci Rep (2015)

The change of delithiation (open symbol) and lithiation (solid symbol) capacities of Li21Si5(0.2–2 μm) included in the Cu-pellet electrode or a sheet electrode.Current density is 50 mA g−1. Capacity is calculated based on (a) Li21Si5 and (b) the total electrode weight, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4308695&req=5

f7: The change of delithiation (open symbol) and lithiation (solid symbol) capacities of Li21Si5(0.2–2 μm) included in the Cu-pellet electrode or a sheet electrode.Current density is 50 mA g−1. Capacity is calculated based on (a) Li21Si5 and (b) the total electrode weight, respectively.
Mentions: Fig. 7a shows the lithiation/delithiation capacities of a half-cell including the sheet electrode at 50 mA g−1. For comparison, the data of the Cu pellet electrode consisting of Li21Si5(0.2–2 μm) are also plotted. The pre-delithiation capacity of Li21Si5(0.2–2 μm) in the sheet electrode is 1219 mAh g−1, which is higher than the case of the Cu pellet electrode. Such high pre-delithiation capacity suggests that Li-Si alloy does not react with PTFE owing to the carbon-coating. The 1st lithiation/delithiation capacities are 1598/1457 mAh g−1, almost the same as the case of the Cu pellet electrode. In addition, the 10th lithiation/delithiation capacities (1220/1179 mAh g−1) are higher than those in the pellet electrode. Thus, Li21Si5(0.2–2 μm) embedded in the sheet electrode exhibits no less performance than the case of the Cu pellet electrode. Fig. 7b compares the capacities of these two electrodes, based on the weight of the total electrode weight. By preparing the lighter sheet electrode, the capacity based on the whole electrode weight can be greatly increased. Thus, carbon-coating is an effective way to avoid undesirable reactions between Li-Si alloy and the binder polymer, and would be crucial to utilize Li-rich Li-Si alloy as a lithium-containing negative electrode. This work has revealed the promising potential of Li-rich Li-Si alloy and demonstrated the method to prepare a light electrode sheet, based on the data obtained at early stage of charge/discharge. To achieve a long cycling life and to make the Li-Si alloy more practical, further improvement must be necessary, such as optimization of particle size, formation of composites with carbon, and/or appropriate surface oxidation38. We hope that this work could be a starting point of such future works.

Bottom Line: Since Li-Si is free from severe constriction/expansion upon delithiation/lithiation, it shows much better cyclability than Si.The feasibility of the Li-Si alloy is further examined by constructing a full-cell together with a lithium-free positive electrode.Though Li-Si alloy is too active to be mixed with binder polymers, the coating with carbon-black powder by physical mixing is found to prevent the undesirable reactions of Li-Si alloy with binder polymers, and thus enables the construction of a more practical electrochemical cell.

View Article: PubMed Central - PubMed

Affiliation: 1] Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan [2] Division of Chemical Process Engineering, Graduate School of Engineering, Hokkaido University, N13W8 Kita-ku, Sapporo 060-8628, Japan.

ABSTRACT
Lithium-ion batteries (LIBs) are generally constructed by lithium-including positive electrode materials, such as LiCoO2, and lithium-free negative electrode materials, such as graphite. Recently, lithium-free positive electrode materials, such as sulfur, are gathering great attention from their very high capacities, thereby significantly increasing the energy density of LIBs. Though the lithium-free materials need to be combined with lithium-containing negative electrode materials, the latter has not been well developed yet. In this work, the feasibility of Li-rich Li-Si alloy is examined as a lithium-containing negative electrode material. Li-rich Li-Si alloy is prepared by the melt-solidification of Li and Si metals with the composition of Li21Si5. By repeating delithiation/lithiation cycles, Li-Si particles turn into porous structure, whereas the original particle size remains unchanged. Since Li-Si is free from severe constriction/expansion upon delithiation/lithiation, it shows much better cyclability than Si. The feasibility of the Li-Si alloy is further examined by constructing a full-cell together with a lithium-free positive electrode. Though Li-Si alloy is too active to be mixed with binder polymers, the coating with carbon-black powder by physical mixing is found to prevent the undesirable reactions of Li-Si alloy with binder polymers, and thus enables the construction of a more practical electrochemical cell.

No MeSH data available.


Related in: MedlinePlus