電気自動車やデバイスのための、より安全で長寿命の電力貯蔵につながる技術革新 Innovation could lead to safer, longer-lasting power storage for electric vehicles and devices
2022-09-21 カリフォルニア大学校アーバイン校(UCI)
コバルトの代替物として一般的なニッケルを主成分とする正極に、他の金属元素を混合して熱的・化学機械的不安定性を克服する方法を説明している。
『高エントロピー・ドーピング』と呼んでいる手法によって、極めて高い耐熱性と、繰り返しの充放電サイクルに対する安定性を備えた、コバルトフリー層状カソードの製造に成功した。
研究チームは、遷移金属であるマグネシウム、チタン、マンガン、モリブデン、ニオブを組み合わせたHE-LMNOを構造体の内部に用い、その表面と他の電池材料との界面にこれらの鉱物のサブセットを用いて、組成的に複雑な高エントロピー・ドーピングにより様々な問題を解決しようと考えた。
放射光X線回折、透過型電子顕微鏡、3Dナノトモグラフィーなどの装置を用いて、このゼロコバルト正極が、繰り返し使用しても体積変化がゼロという前例のない特性を示すことを突き止めた。
＜関連情報＞
- https://news.uci.edu/2022/09/21/uci-and-national-lab-researchers-develop-a-cobalt-free-cathode-for-lithium-ion-batteries/
- https://www.nature.com/articles/s41586-022-05115-z
ゼロ歪みゼロコバルト層カソードの組成複雑化ドーピング Compositionally complex doping for zero-strain zero-cobalt layered cathodes
Rui Zhang,Chunyang Wang,Peichao Zou,Ruoqian Lin,Lu Ma,Liang Yin,Tianyi Li,Wenqian Xu,Hao Jia,Qiuyan Li,Sami Sainio,Kim Kisslinger,Stephen E. Trask,Steven N. Ehrlich,Yang Yang,Andrew M. Kiss,Mingyuan Ge,Bryant J. Polzin,Sang Jun Lee,Wu Xu,Yang Ren & Huolin L. Xin
Nature Published:21 September 2022
DOI:https://doi.org/10.1038/s41586-022-05115-z
Abstract
The high volatility of the price of cobalt and the geopolitical limitations of cobalt mining have made the elimination of Co a pressing need for the automotive industry1. Owing to their high energy density and low-cost advantages, high-Ni and low-Co or Co-free (zero-Co) layered cathodes have become the most promising cathodes for next-generation lithium-ion batteries2,3. However, current high-Ni cathode materials, without exception, suffer severely from their intrinsic thermal and chemo-mechanical instabilities and insufficient cycle life. Here, by using a new compositionally complex (high-entropy) doping strategy, we successfully fabricate a high-Ni, zero-Co layered cathode that has extremely high thermal and cycling stability. Combining X-ray diffraction, transmission electron microscopy and nanotomography, we find that the cathode exhibits nearly zero volumetric change over a wide electrochemical window, resulting in greatly reduced lattice defects and local strain-induced cracks. In-situ heating experiments reveal that the thermal stability of the new cathode is significantly improved, reaching the level of the ultra-stable NMC-532. Owing to the considerably increased thermal stability and the zero volumetric change, it exhibits greatly improved capacity retention. This work, by resolving the long-standing safety and stability concerns for high-Ni, zero-Co cathode materials, offers a commercially viable cathode for safe, long-life lithium-ion batteries and a universal strategy for suppressing strain and phase transformation in intercalation electrodes.
