2020 Fiscal Year Research-status Report
Application of vertically aligned one-dimensional van der Waals heterostructures in lithium sulfur battery
| Project/Area Number |
20KK0114
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| Research Institution | The University of Tokyo |
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Principal Investigator |
項 栄 東京大学, 大学院工学系研究科(工学部), 准教授 (20740096)
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| Co-Investigator(Kenkyū-buntansha) |
井ノ上 泰輝 大阪大学, 工学研究科, 助教 (00748949)
熊本 明仁 東京大学, 大学院工学系研究科(工学部), 客員共同研究員 (70724590)
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| Project Period (FY) |
2020-10-27 – 2023-03-31
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| Keywords | 一次元ファンデルワールスヘテロ構造 / リチウム‐硫黄電池 / 電子顕微鏡 |
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| Outline of Annual Research Achievements |
For material synthesis, we have successfully synthesized vertically aligned SWCNTs on quartz and silicon substrate. We also confirmed that BN and MoS2 can be formed on the vertical array. SEM, Raman, optical absorption, TEM have confirmed the existence of BN and MoS2. We have also reveled that, when SWCNTs forms a bundle, BN and MoS2 will wrap over the entire bundle, instead of isolating the SWCNTs in a bundle and coat in each SWCNT. Therefore, understanding and controlling the bundle structure will be important to understand the S loading in for the vertically aligned heteronanotube array.
On the other hand, to understand and improve the performance of Li anode, TMS additives decompose before FEC to enhance the uniformity of Li deposition. Thus, sulfuryl-containing components and increased content of Li2O were introduced into fluorinated SEI, further improving the homogeneity of SEI and promoting more uniform Li deposition than that only in fluorinated SEI. While TMS additives were applied in a Li metal battery with an ultrathin Li anode (33 μm), a high loading LiNi0.5Co0.2Mn0.3O2 (NCM523) cathode (2.5 mA h /cm2 ), and lean electrolyte (7.7 g/ A h), 130 cycles were achieved in Li|NCM523 batteries with TMS additives compared with 60 cycles without additives. This work not only proposes a new type of additives to suppress Li dendrites but also provides guidance for the design of electrolyte formulations to stabilize ultrathin Li anode in practical batteries.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
We have successfully synthesized vertically aligned SWCNTs on quartz and silicon substrate. We also confirmed that BN and MoS2 can be formed on the vertical array. SEM, Raman, optical absorption, TEM have confirmed the existence of BN and MoS2. This year, we co-authored two publications with the international collaborators on the nanostructure and origin of sulfuryl-containing components in SEI from sulfate
additives for stable cycling of ultrathin lithium metal anodes.
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| Strategy for Future Research Activity |
The next research will be focused on two parts.
1. We will further optimize the synthesis technique of vertically aligned heteronanotube array. This includes the optimization of the growth of carbon nanotube template alone, as well as the the optimization of the coating condition of BN and MoS2.
2. We will also characterize the S loaded vertically aligned heteronanotube array, this include the observation of the geometry of composite and also the characterization of interface between S and the heteronanotube. TEM will employed for this experiment.
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| Causes of Carryover |
Because of the global pandemic of Covid-19, the research activities, particularly the international joint experiments are to certain extent delayed. We are optimizing the material and battery from each side. The joint TEM experiments and the related cost will be performed in the next fiscal year.
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