Sodium-Ion Battery Cathode Material Synthesized By Spray Pyrolysis

Lithium-ion batteries have been the dominant choice for batteries for decades, however there are concerns related to the limited availability of lithium, which could potentially increase the cost and affect further implementation. As a promising alternative, sodium-ion batteries have attracted significant attention in recent years [1, 2]. The potential markets for sodium-ion batteries could range from devices where cycle life and cost are more prevailing factors than energy density, such as grid-scale energy storage for smart grid applications. A single-step, facile spray pyrolysis is being evaluated in this group for the synthesis of sodium-ion battery cathode materials.

In the current study, Na_0.44MnO₂ was selected due to its promising electrochemical performance, unique structure, and its similarity to transition metal oxides [3, 4]. Figure 1 shows the SEM image of Na_0.44MnO₂ annealed at 800 ºC. The material demonstrates a uniform, rod-like morphology. Figure 2 displays the XRD data of samples annealed at different temperatures for two hours. Na_0.44MnO₂ has an orthorhombic lattice cell (pbam space group) and is isostructural with Na₄Mn₄Ti₅O₁₈. The sample annealed at 700 ºC displays impurity peaks around the 30º 2θ. These impure phases may be related to the incomplete decomposition at this temperature. There are no additional phases observed in the 800 ºC and 900 ºC annealed samples. Figure 3 shows the first cycle voltage profile of the Na_0.44MnO₂ (annealed at 800 ºC) cell at C/10, where 1C equals to 120 mAg^-1. The material demonstrates a discharge capacity of 100 mAhg^-1, which is comparable to materials reported from other synthesis methods.

References:

1.      M.D. Slater, D. Kim, E. Lee, C.S. Johnson, Advanced Functional Materials, Sodium-Ion Batteries, 23(8), 2013, 947-958.

2.     V. Palomares, P. Serras, I. Villaluenga, K.B. Hueso, J. Carretero-Gonzalez, T. Rojo, Energy and Environmental Science, Na-ion batteries, recent advances and present challenges to become low cost energy storage systems, 5(3), 2012, 5884-5901.

3.      F. Sauvage, L. Laffont, J.M. Tarascon, E. Baudrin, Inorganic Chemistry, Study of the insertion/deinsertion mechanism of sodium into Na_0.44MnO₂, 46(8), 2007, 3289-3294.

4.      L.W. Zhao, J.F. Ni, H.B. Wang, L.J. Gao, RSC Advances, Na_0.44MnO₂-CNT electrodes for non-aqueous sodium batteries, 3(18), 2013, 6650-6655