Characterization and Electrochemical Performance of Na(Ni,Fe,Mn)O2 for Sodium-Ion Battery Cathodes

Given the escalating demand for sustainable energy storage solutions, sodium-ion batteries (SIBs) have emerged as formidable contenders against lithium-ion batteries (LIBs), capitalizing on the abundant and cost-effective nature of sodium resources. A pivotal determinant in advancing SIB technology lies in the quest for efficient anode materials, which significantly influence the overall performance and stability of the battery system. Among potential candidates, Na(Ni,Fe,Mn)O2, a layered transition metal oxide, holds promise as an anode material for SIBs. To explore this potential, we employed the solid-state reaction method to synthesize and analyze three novel anode materials: NaNiO 2 , NaNi 0.9 Fe 0.05 Mn 0.05 O 2 , and NaNi 0.8 Fe 0.1 Mn 0.1 O 2 . Stoichiometric proportions of Na 2 O 2 , NiO, Fe 2 O 3 , and Mn 2 O 3 served as the starting materials, supplemented with an additional 15% Na 2 O 2 to ensure thorough decomposition during synthesis. Following synthesis, we conducted a series of analyses to elucidate the structural characteristics of the materials. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to confirm the basic surface morphology, crystal structure, and phase composition. X-ray photoelectron spectroscopy (XPS) analysis provided insights into the elemental composition and chemical states. Further investigation into the nanostructure and electrochemical performance was carried out using transmission electron microscopy (TEM) and in-situ XRD. TEM analysis revealed crystal defects, interface structures, and nanoparticle morphology, while in-situ XRD allowed for real-time observation of crystal structural changes during cycling. Subsequently, the synthesized materials were utilized as active materials to fabricate Half Coincells, with sodium metal serving as the cathode. Electrochemical evaluations, including constant current charge-discharge tests at various current densities and rate performance assessments, were conducted. These evaluations enabled us to assess the specific capacity, rate capability, and cycling stability of each material, facilitating a comparative analysis of their suitability as anode materials for SIBs. In summary, this study employs a comprehensive analytical framework to explore the structural characteristics and electrochemical behavior of Na(Ni,Fe,Mn)O2 for SIB applications. By integrating advanced characterization techniques with electrochemical measurements, we aim to uncover key insights into its potential as a high-performance cathode material, advancing the development of sustainable energy storage technologies. This research was supported by the NRF funded by the MSIT and MEST (grant numbers NRF-2021R1A4A1022198, NRF-2022R1A2B5B01001943, and NRF-2018R1A5A1025594). Figure 1