2017 Fiscal Year Annual Research Report
| Project/Area Number |
17J09973
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| Research Institution | Waseda University |
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Principal Investigator |
Wu Yunwen 早稲田大学, 理工学術院, 特別研究員(DC2)
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| Project Period (FY) |
2017-04-26 – 2019-03-31
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| Keywords | lithium sulfide cathode / chemical lithaition / Li metal free full cell / nano structured Li2S |
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| Outline of Annual Research Achievements |
In this year, we mainly proceeded the research in the three parts.
(1) A chemical pre-lithiation method on S cathode has been developed. It is first time report the chemical pre-lithaition at room temperature, which is attributed by employing a 3D current collector. This on-site pre-lithiation method can make contribution to the in-situ pre-lithiation in a lithium metal free battery. The pre-lithiated Li2S cathode at room temperature showed stable cycling performance with a 600 mAhg-1 capacity after 100 cycles at 0.1 C-rate and high capacity of 500 mAhg-1 at 2 C-rate.
(2) A novel S Li ion battery has been successfully assembled by using the nano hollow structured carbon host in S cathode and the pre-lithiated graphite anode. This work has largely alleviated the capacity fading issue existing in sulfur graphite full cell setup and the safety hazard existing in S-Li half cell, which reached the best performance ever reported. Specifically, this novel sulfur Li ion battery delivers high specific capacity (1207 mAh g-1 at 0.1 C and 925 mAh g-1 at 0.2 C) and low capacity fading rate (0.19 % per cycle), making it a remarkable work on the way forward to next-generation Li ion battery with higher capacity and better reliability. We believe this reported high capacity sulfur graphite full cell will make progress on pushing forward the commercialization of S Li ion battery.
(3) It is atempted to synthesis the Li2S nanoparticles directly without using the S cathode. In this case, nano structured Li2S particles with a uniform size can be obtained.
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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
On the one hand, the Li2S-graphite metallic Li free full cell has been successfuly assembled. It means that the ultimate goal of the metallic Li free full battery has been realized. On the other hand, the high performance Li2S nanoparticles have been innovatively synthesized by using the organolithium reagent. It shows improved capacity performance in the Li2S-Li half cell.
The next step is the apply the high performance Li2S cathode in the metallic Li free full battery. It is expected that high cycling performance of the full cell will be achieved.
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| Strategy for Future Research Activity |
The Li2S nanoparticles have sucessfuly synthized by chemcial method.The Li2S catode fabricated has proven to be good cyclability. However, in order to realize high performance metallic Li free sulfur full cell, it is necessary to improve the performance both in cathode and anode.
I will use the synthesized nanoparticles to mix with good performance S host materials to make the core/ shell structures. After making the Li2S/ host material composite particles, the Li2S cathode will be fabricated by a simple coating process. This method shows advantages in high Li2S weight ratio and high energy density. It is expected good results will be achieved in the coming year.
As aforementioned the breakthrough obtained by my previous work on fabricating high energy density Li2S cathode, it will be an inspiring work to assemble the high energy density S Li-ion battery by pair with the high-performed novel nanostructured Si anode. I will also work on the electrolyte system which show compatibility both for cathodes and anodes. The electrolyte system is expected to form stable solid electrolyte interphase on the anode which could both well-prevented internal shorts and improve the anode performance. It is expected to make the Li2S-Si metallic Li free S battery which should own high energy density and long cycle life. As a result, possible contributions will be made to pushing forward the commercialization of S battery, promoting the development of advanced electronic devices.
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