Li Mengya, Wood David L, Bai Yaocai, Essehli Rachid, Amin Md Ruhul, Jafta Charl, Muralidharan Nitin, Li Jianlin, Belharouak Ilias
Energy and Transportation Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States.
Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, Tennessee 37996, United States.
ACS Appl Mater Interfaces. 2020 May 27;12(21):23951-23958. doi: 10.1021/acsami.0c04513. Epub 2020 May 15.
An engaging area of research in sodium-ion batteries (SIBs) has been focusing on discovery, design, and synthesis of high-capacity cathode materials in order to boost energy density to levels close enough to that of state-of-the-art lithium-ion batteries. Of particular interest, P2-type layered oxide, NaFeMnO, has been researched as a potential cathode in SIBs based on its high theoretical capacity of 260 mA h/g and use of noncritical materials. However, the reported synthesis methods are not only complex and energy-demanding but also often yield inhomogeneous and impure materials with capacities less than 200 mA h/g under impractical test conditions. Here, we report a novel synthesis route using low-temperature eutectic reaction to produce highly homogeneous, crystalline, and impurity-free P2-NaFeMnO with enhanced Na-ion diffusivity and kinetics. The overall electrochemical performances of the Na-ion cells have been improved by pairing the P2-cathode with presodiated hard carbon anodes, leading to reversible capacities in the range of 180 mA h/g. This new approach is a contribution toward the simplification of synthesis and scalability of sodium-based cathodes with high crystallinity and fine-tuned morphology and the realization of a sodium-ion battery system with lower cost and improved electrochemical performance.
钠离子电池（SIBs）一个引人关注的研究领域一直聚焦于高容量阴极材料的发现、设计和合成，以便将能量密度提高到接近最先进锂离子电池的水平。特别值得关注的是，P2型层状氧化物NaFeMnO，因其260 mA h/g的高理论容量以及使用非关键材料，已被作为SIBs中的一种潜在阴极进行研究。然而，报道的合成方法不仅复杂且耗能，而且在不切实际的测试条件下，通常会产生不均匀且不纯的材料，其容量低于200 mA h/g。在此，我们报道了一种利用低温共熔反应的新型合成路线，以制备具有高度均匀性、结晶性且无杂质的P2-NaFeMnO，其具有增强的钠离子扩散率和动力学性能。通过将P2阴极与预钠化硬碳阳极配对，钠离子电池的整体电化学性能得到了改善，可逆容量在180 mA h/g范围内。这种新方法有助于简化合成过程，提高钠基阴极的可扩展性，使其具有高结晶度和微调的形态，并实现具有更低成本和改善电化学性能的钠离子电池系统。
