Tailored P/O Type Phase Dependent Ni and Co-Free Cathode for Sodium-Ion Batteries

The extensive application of Lithium-ion batteries (LIBs) are severely affected by<br/>limited lithium reserves and environmental problems associated with lithium mining and processing [1]. This threatening condition has pushed the researchers to look for the alternative of LIBs. Sodium-ion batteries (NIBs) are the best alternative of Li-ion batteries due to its similar chemistry, cost-effectiveness, sustainability and thus it can help in lessening the burden on Li-ion batteries [2]. To achieve high performance in NIBs, cathode material is the limiting factor which makes the advance of stable and efficient cathodes highly crucial. Furthermore, the resources limitations and serious geopolitical concerns around the Cobalt and Nickel have driven the exploration of Fe-Mn based system for the development of cathode [3]. The present work aims to synthesized a tailored mixed phase P/O having Ni and Co-free cathode using the solid-state method. Both P and O type has their own advantages and limitations. P2-type oxides have wider transport channels to facilitate the diffusion of Na+ ions, resulting in a better rate capability. Whereas, higher sodium-ion content in O3-type oxides helps in achieving<br/>higher capacities [4]. In our work, we have tried to utilize the assistance of both P and O type phase in improving the rate capability and also the capacity. By changing the concentration of Na-ion, an optimized mixed phase is synthesized. The effect of this coexistence of both phases on the electrochemical performance is investigated and obtained cathode has shown an impressive results with capacity of more than 130 mAh/g. Unlike several other single-phase materials in the Na-Fe–Mn system, biphasic optimized composition displays much-improved cyclability in the 2.4-4.2V range.<br/>References<br/>[1] M. D. Slater, D. Kim, E. Lee and C. S. Johnson, Sodium-ion batteries, Adv. Funct.<br/>Mater., 2013, 23, 947–958.<br/>[2] S. P. Ong, V. L. Chevrier, G. Hautier, A. Jain, C. Moore, S. Kim, X. Ma and G.<br/>Ceder, Voltage, stability and diffusion barrier differences between sodium-ion and<br/>lithium-ion intercalation materials, Energy Environ. Sci., 2011, 4, 3680.<br/>[3] M. H. Han, E. Gonzalo, G. Singh, T. Rojo, A comprehensive review of sodium<br/>layered oxides: powerful cathodes for Na-ion batteries, Energy Environ.Sci. 2015, 8, 81.<br/>[4] W. Zuo, X. Liu, J. Qiu, D. Zhang, Z. Xiao, J. Xie, F. Ren, J. Wang, Y. Li, G.F. Ortiz,<br/>W. Wen, S. Wu, M.-S. Wang, R. Fu, Y. Yang, Engineering Na+-layer spacings to<br/>stabilize Mn-based layered cathodes for sodium-ion batteries, Nat. Commun., 2021, 12