2022-09-26 テキサス大学オースチン校(UT Austin)
その結果、既存の市販の電極を用いたバッテリーと比較して、電気自動車の1回の充電で2倍の航続距離を実現できる可能性がある電極が完成した。
今回の発見のポイントは、電極のビルディングブロックとして薄い2次元材料を使用し、それらを積層して厚みを作り、磁場を用いてその向きを操作すること。研究チームは、作製過程で市販の磁石を使って二次元材料を垂直に並べ、電極内をイオンが高速で移動する車線を作り出した。
この電極は、機械的強度が高く、導電率が高く、独自の構造によってリチウムイオンの輸送が促進されるため、部分的に優れた電気化学的性能を示しす。
この電極を市販の電極と比較するとともに、同じ材料を用いて水平に配置した電極も作製し、実験的にコントロールした。その結果、水平電極では2時間30分かかったのに対し、垂直電極では30分で50%のエネルギーレベルまで充電することができた。
＜関連情報＞
- https://news.utexas.edu/2022/09/26/magnetic-field-helps-thick-battery-electrodes-tackle-electric-vehicle-challenges/
- https://www.pnas.org/doi/10.1073/pnas.2212777119
高密度厚膜電池電極のための垂直集積型ナノシートネットワーク Vertically assembled nanosheet networks for high-density thick battery electrodes
Zhengyu Ju, Steven T. King, Xiao Xu, +6, Xiao Zhang, Kasun U. Raigama, Kenneth J. Takeuchi, Amy C. Marschilok, Lei Wang, Esther S. Takeuchi and Guihua Yu
Proceedings of the National Academy of Sciences Published:September 26, 2022
DOI:https://doi.org/10.1073/pnas.2212777119
Significance
The unprecedented growth of electric vehicles during the past decade has played an indispensable role in paving the way for a carbon-neutral future. Two-dimensional materials have shown promising properties in high-power energy storage systems; however, diminished electrochemical performance is observed in nanosheet-based thick electrodes suffering from sluggish transport kinetics. Here, we develop a method of controlling nanosheet assembly via the combination of an external magnetic field and drying-based densification to prepare high-density, low-tortuosity electrodes. The vertically interconnected nanosheet network provides efficient pathways for mass transport, delivering both high areal and volumetric capacities far beyond those of commercial electrodes. The methodology demonstrated is potentially universal in aligning nanosheets in a vertical and dense manner for advanced battery electrodes.
Abstract
As one of the prevailing energy storage systems, lithium-ion batteries (LIBs) have become an essential pillar in electric vehicles (EVs) during the past decade, contributing significantly to a carbon-neutral future. However, the complete transition to electric vehicles requires LIBs with yet higher energy and power densities. Here, we propose an effective methodology via controlled nanosheet self-assembly to prepare low-tortuosity yet high-density and high-toughness thick electrodes. By introducing a delicate densification in a three-dimensionally interconnected nanosheet network to maintain its vertical architecture, facile electron and ion transports are enabled despite their high packing density. This dense and thick electrode is capable of delivering a high volumetric capacity >1,600 mAh cm−3, with an areal capacity up to 32 mAh cm−2, which is among the best reported in the literature. The high-performance electrodes with superior mechanical and electrochemical properties demonstrated in this work provide a potentially universal methodology in designing advanced battery electrodes with versatile anisotropic properties.
