| 研究実績の概要 |
The use of collectors with a hierarchically porous structure can optimize the deposition behavior of lithium (Li) metal to some extent. However, in practical studies, Li metal was found to be difficult to be deposited into the upright channel as expected, in its place, the Li metal exhibits a different deposition behavior than we expected. When the channel's diameter is large (greater than 20 μm), lithium metal typically accumulates near the tube wall opening. Conversely, when the diameter is small (less than 5 μm), lithium metal deposits solely on the current collector's upper surface. Even after incorporating materials that promote underpotential deposition (UPD) or irregular nucleation of lithium metal (such as silver) into the metal framework, lithium metal will amass near the channel entrance, creating an unsupported lithium layer. This occurs because the initially deposited lithium metal on the upper surface acts as a "nucleus," encouraging subsequent deposition primarily on the electrode surface. The resulting lithium metal plating obstructs ion transport into the channel, causing deposition to predominantly occur in the 3D structure's shallow region. Moreover, we find that the use of such materials can improve the performance of the sulfur cathode in lithium-sulfur batteries very well. The porous metal possesses an exceptional capacity to catalyze the cathodic reactions, while its multi-level porous architecture effectively enhances the discharge performance of high-capacity lithium-sulfur batteries.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
We have now confirmed the usefulness of current collectors with different pore sizes for Li metal deposition (or sodium metal deposition) in various electrolytes. We believe that the use of a current collector with a channel structure is of very limited help in optimizing the performance of lithium metal anodes. However, when we use porous nickel with the same channel structure as the current collector for the sulfur-polyacrylonitrile (S@PAN) cathode of lithium-sulfur batteries, its unique porous structure enhances the catalytic effect on the cathodic reactions and greatly improves the capacity and cyclic reversibility of the cathode. Hence, I believe that this study has basically completed the corresponding research as planned and some different results has been achieved than expected.
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| 今後の研究の推進方策 |
Since we have confirmed that optimizing the performance of the Li metal anode using a structured host cannot optimize its performance to a level sufficient for real-world use, but the porous nickel (Ni) with similar channel structure obtained by the same material preparation scheme can greatly improve the performance of sulfur cathode in lithium-sulfur batteries.
The lithium-sulfur batteries using such current collectors can have an ultra-high capacity of 1800 mAh g-1 at >5 mg cm-2 cathode loading,and can be stably cycled for more than 50 cycles. We have now found that the hierarchically porous structure of the skeleton is a key point to enhance the electrode performance, In this year's research we will elucidate this issue to boost the development of high performance Li metal batteries.
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