Biocarbon-directed vertical δ-MnO₂ nanoflakes for boosting lithium-ion diffusion kinetics
Lin, Y.; Tian, H.; Qian, J.; Yu, M.; Hu, T.; Lassi, U.; Chen, Z.; Wu, Z. (2022-06-30)
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Sisältö avataan julkiseksi: 30.06.2024
Y. Lin, H. Tian, J. Qian, M. Yu, T. Hu, U. Lassi, Z. Chen, Z. Wu, Biocarbon-directed vertical δ-MnO2 nanoflakes for boosting lithium-ion diffusion kinetics, Materials Today Chemistry, Volume 26, 2022, 101023, ISSN 2468-5194, https://doi.org/10.1016/j.mtchem.2022.101023
© 2022. This manuscript version is made available under the CC-BY-NC-ND 4.0 license by http://creativecommons.org/licenses/by-nc-nd/4.0/.
https://creativecommons.org/licenses/by-nc-nd/4.0/
https://urn.fi/URN:NBN:fi-fe202301162882
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Abstract
Manganese dioxide (MnO₂) with high theoretical capacity (1230 mAh/g) and low cost is considered as a promising anode material for next generation high energy density lithium-ion (Li⁺) batteries. However, the intrinsic low electric conductivity and volume change during cycling process limit its applications. In this work, a unique δ-MnO₂/C composite has been synthesized through the directed growth of 2D δ-MnO₂ nanosheets on the cabbage-leaf-derived biocarbon. The biocarbon acts as both structure buffer to accommodate the volume expansion and conductive agent to promote electron and ion transport. Moreover, oriented δ-MnO₂ nanosheets are beneficial for increasing contact area between electrode and electrolyte, thus providing more active sites and shortening the Li+ transmission routes. Electrochemical performances show that δ-MnO₂/C displays large reversible capacity (754 mAh/g after 250 cycles at current density of 0.1 A/g), excellent rate capability as well as low charge transfer resistance (17.3 Ω), and high Li⁺ diffusion rate (DLi⁺ = 2.91 × 10⁻¹⁴ cm²/s) during the cycles. Furthermore, the density functional theory calculations reveal the lower Li⁺ migration barrier energies and improved Li+ diffusion kinetics in δ-MnO₂/C hetero-layer. This study provides a novel strategy to design advanced nanocomposites, using natural plant-leaf derivatives as structure-directing agents, for the next generation energy storage and conversion systems.
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