Hunan University researchers have created a layered oxide cathode for rechargeable lithium-ion batteries that requires incredibly little cobalt to achieve high safety, long life, and fast charging. The study has been published in the National Science Open journal.
Lithium-ion secondary batteries have been instrumental in the recent global explosion of electric vehicles. Cobalt is typically present in lithium-ion battery cathodes to guarantee fast charging. However, the cost of lithium-ion battery materials has increased dramatically due to the limited supply of cobalt and the rising demand for it. The main difficulty has been lowering cobalt consumption without sacrificing fast charging capabilities.
By maximizing the distribution of cobalt in high-nickel layered oxide cathode particles, the researchers were able to address this problem and create a sensible structure consisting of a stable bulk phase, a gradient Li+ ions conductive layer, and a robust conductive protective layer.
The material's ionic and electronic conductivity was greatly increased, according to analysis, by the strong conductive protective layer and gradient Li+ ions conductive layer. As a result, even with extremely little cobalt, this structure demonstrated excellent rate performance (fast charging).
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Furthermore, exceptional cycling stability and safety were achieved by the bulk phase with moderate cation mixing and the surface conductive protective layer, which effectively ensured material stability. The designed cathode has doubled its rate performance (5 C) and maintained 90.4% of its capacity after 300 cycles at high voltage in terms of battery performance throughout the entire cell. These benefits imply that the cathode's design has a lot of potential for real-world uses.
Our study provides strong evidence that rational structural design can significantly reduce cobalt content while maintaining high rate performance and long life in batteries. This offers new insights for developing low-cost, high-performance lithium-ion battery materials.
Bingan Lu, Professor and Study Senior Author, Hunan University
The study shows that simultaneously designing bulk phase and surface crystal structure is an efficient way to guarantee excellent electrochemical performance at a lower cost for cathode materials with good structural stability but poor kinetic performance.
The Chinese National Natural Science Foundation provided funding for this study.
Journal Reference:
Zhang, Q., et al. (2024) Surface Cobaltization for Boosted Kinetics and Excellent Stability of Nickel-rich Layered Cathodes. National Science Open. doi.org/10.1360/nso/20240010