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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

Charge/discharge curves of (a) a half-cell of MnO2 and full-cells constructed with (b) MnO2/Li21Si5(0.2–2 μm) and (c) MnO2/pre-lithiated graphite at 10 mA g−1.
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f6: Charge/discharge curves of (a) a half-cell of MnO2 and full-cells constructed with (b) MnO2/Li21Si5(0.2–2 μm) and (c) MnO2/pre-lithiated graphite at 10 mA g−1.

Mentions: We then examine the feasibility of the Li-rich Li-Si alloy as a Li-containing negative electrode by combining it with a Li-free positive electrode. Commercially available MnO2 powder was used as the latter. Before constructing a full cell, charge/discharge behavior of MnO2 is examined with a half cell, as shown in Fig. 6a. Although MnO2 shows a relatively large irreversible capacity of 119 mAh g−1 in the 1st cycle, those in the 2nd and the 3rd cycles are reduced down to ca. 20 mAh g−1. Its 2nd and 3rd lithiation capacities are 140 and 132 mAh g−1, respectively. Next, a full cell was constructed by using Li21Si5(0.2–2 μm) and MnO2 as negative and positive electrodes, respectively. Fig. 6b shows its charge/discharge curves. Note that the amount of MnO2 is ca. 3 times larger than that of Li21Si5(0.2–2 μm) to balance the Li storage capacities in negative and positive electrodes. The full cell shows the 1st discharge and charge capacities of 479 and 304 mAh g−1, respectively. The first irreversible capacity is relatively high (175 mAh g−1). This is mainly due to the irreversible capacity of MnO2, as shown in Fig. 6a. Based on the pre-delithiation capacities of Li21Si5(0.2–2 μm) (Fig. 3a) and the 1st charge/discharge capacity of MnO2 (Fig. 6a) as well as their amounts in each of the electrodes, the 1st discharge/charge capacities of the full cell is estimated as 745/349 mAh g−1-Li21Si5. Note that the large difference between discharge and charge capacities is due to the large irreversible capacity of MnO2. The reason why the actual capacities are lower than the estimation would be the different potential profiles between half cells (Fig. 3a and 6a) and the full cell (Fig. 6b) in each of electrodes. By the same way, the 2nd discharge/charge capacities are also estimated as 466/389 mAh g−1-Li21Si5, while the actual values are 331/300 mAh g−1-Li21Si5. The full cell shows almost reasonable capacities. In order to evaluate the validity of the Li-rich Li-Si alloy as a lithium-containing negative electrode, we carried out a comparative experiment by using pre-lithiated graphite (LiC6), which is popularly used as a lithium-containing negative electrode in lithium-ion capacitors, and is expected as another candidate of a counter material of sulfur electrode (Fig. 1). Its charge/discharge curves are shown in Fig. 6c. Due to the smaller capacity of the pre-lithiated graphite (339 mAh g−1-LiC6), its full-cell shows much lower capacity than the case of Li21Si5(0.2–2 μm) (Fig. 6b), clearly indicating the advantage of the Li-rich Li-Si alloy as a promising lithium-containing negative electrode for next-generation high-energy LIBs.


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)

Charge/discharge curves of (a) a half-cell of MnO2 and full-cells constructed with (b) MnO2/Li21Si5(0.2–2 μm) and (c) MnO2/pre-lithiated graphite at 10 mA g−1.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f6: Charge/discharge curves of (a) a half-cell of MnO2 and full-cells constructed with (b) MnO2/Li21Si5(0.2–2 μm) and (c) MnO2/pre-lithiated graphite at 10 mA g−1.
Mentions: We then examine the feasibility of the Li-rich Li-Si alloy as a Li-containing negative electrode by combining it with a Li-free positive electrode. Commercially available MnO2 powder was used as the latter. Before constructing a full cell, charge/discharge behavior of MnO2 is examined with a half cell, as shown in Fig. 6a. Although MnO2 shows a relatively large irreversible capacity of 119 mAh g−1 in the 1st cycle, those in the 2nd and the 3rd cycles are reduced down to ca. 20 mAh g−1. Its 2nd and 3rd lithiation capacities are 140 and 132 mAh g−1, respectively. Next, a full cell was constructed by using Li21Si5(0.2–2 μm) and MnO2 as negative and positive electrodes, respectively. Fig. 6b shows its charge/discharge curves. Note that the amount of MnO2 is ca. 3 times larger than that of Li21Si5(0.2–2 μm) to balance the Li storage capacities in negative and positive electrodes. The full cell shows the 1st discharge and charge capacities of 479 and 304 mAh g−1, respectively. The first irreversible capacity is relatively high (175 mAh g−1). This is mainly due to the irreversible capacity of MnO2, as shown in Fig. 6a. Based on the pre-delithiation capacities of Li21Si5(0.2–2 μm) (Fig. 3a) and the 1st charge/discharge capacity of MnO2 (Fig. 6a) as well as their amounts in each of the electrodes, the 1st discharge/charge capacities of the full cell is estimated as 745/349 mAh g−1-Li21Si5. Note that the large difference between discharge and charge capacities is due to the large irreversible capacity of MnO2. The reason why the actual capacities are lower than the estimation would be the different potential profiles between half cells (Fig. 3a and 6a) and the full cell (Fig. 6b) in each of electrodes. By the same way, the 2nd discharge/charge capacities are also estimated as 466/389 mAh g−1-Li21Si5, while the actual values are 331/300 mAh g−1-Li21Si5. The full cell shows almost reasonable capacities. In order to evaluate the validity of the Li-rich Li-Si alloy as a lithium-containing negative electrode, we carried out a comparative experiment by using pre-lithiated graphite (LiC6), which is popularly used as a lithium-containing negative electrode in lithium-ion capacitors, and is expected as another candidate of a counter material of sulfur electrode (Fig. 1). Its charge/discharge curves are shown in Fig. 6c. Due to the smaller capacity of the pre-lithiated graphite (339 mAh g−1-LiC6), its full-cell shows much lower capacity than the case of Li21Si5(0.2–2 μm) (Fig. 6b), clearly indicating the advantage of the Li-rich Li-Si alloy as a promising lithium-containing negative electrode for next-generation high-energy LIBs.

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