Joshi Akanksha, Chakrabarty Sankalpita, Akella Sri Harsha, Saha Arka, Mukherjee Ayan, Schmerling Bruria, Ejgenberg Michal, Sharma Rosy, Noked Malachi
Department of Chemistry, Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat Gan, 5290002, Israel.
Department of Hydro and Electro Metallurgy, CSIR-Institute of Minerals and Materials Technology Bhubaneswar, Bhubaneswar, Odisha, 751013, India.
Adv Mater. 2023 Dec;35(51):e2304440. doi: 10.1002/adma.202304440. Epub 2023 Nov 12.
Sodium-ion batteries have recently emerged as a promising alternative to lithium-based batteries, driven by an ever-growing demand for electricity storage systems. The present workproposes a cobalt-free high-capacity cathode for sodium-ion batteries, synthesized using a high-entropy approach. The high-entropy approach entails mixing more than five elements in a single phase; hence, obtaining the desired properties is a challenge since this involves the interplay between different elements. Here, instead of oxide, oxyfluoride is chosen to suppress oxygen loss during long-term cycling. Supplement to this, lithium is introduced in the composition to obtain high configurational entropy and sodium vacant sites, thus stabilizing the crystal structure, accelerating the kinetics of intercalation/deintercalation, and improving the air stability of the material. With the optimization of the cathode composition, a reversible capacity of 109 mAh g (2-4 V) and 144 mAh g (2-4.3 V) is observed in the first few cycles, along with a significant improvement in stability during prolonged cycling. Furthermore, in situ and ex situ diffraction studies during charging/discharging reveal that the high-entropy strategy successfully suppresses the complex phase transition. The impressive outcomes of the present work strongly motivate the pursuit of the high-entropy approach to develop efficient cathodes for sodium-ion batteries.
随着对储能系统的需求不断增长，钠离子电池最近已成为锂基电池的一种有前景的替代方案。目前的工作提出了一种用于钠离子电池的无钴高容量阴极，采用高熵方法合成。高熵方法需要在单相中混合五种以上的元素；因此，获得所需的性能是一项挑战，因为这涉及不同元素之间的相互作用。在这里，选择氧氟化物而不是氧化物来抑制长期循环过程中的氧损失。此外，在成分中引入锂以获得高构型熵和钠空位，从而稳定晶体结构，加速嵌入/脱嵌动力学，并提高材料的空气稳定性。通过阴极成分的优化，在最初的几个循环中观察到可逆容量为109 mAh g（2-4 V）和144 mAh g（2-4.3 V），并且在长时间循环期间稳定性有显著提高。此外，充电/放电过程中的原位和非原位衍射研究表明，高熵策略成功地抑制了复杂的相变。目前工作的令人印象深刻的结果强烈推动了对高熵方法的追求，以开发用于钠离子电池的高效阴极。
