Progress and Prospects in Cathode Materials for Sodium-Ion Batteries: Synthesis, Characterization, and Engineering Aspects

The need for sustainable and economically viable energy storage technologies is increasing critically as the world transitions toward renewable energy and electrified transportation. Sodium-ion batteries (SIBs) have emerged as a promising alternative to lithium-ion batteries (LIBs) due to the abundant availability of sodium and the potential for lower costs. However, the development of high-performance cathode materials remains a key challenge in realizing the full potential of SIBs. Recent advancements have focused on improving the electrochemical properties of cathode materials through various strategies, particularly the doping of various cations and anions into layered transition metal oxides (LTMOs). Researchers have enhanced the specific capacity, cycling stability, and rate performance. Doping not only improves structural stability but also mitigates issues such as phase transitions and voltage decay, which are critical for the long-term performance of SIBs. In addition to these advancements, there is a growing priority on eliminating cobalt from cathode materials due to environmental and economic concerns. Cobalt-free alternatives, such as manganese-rich oxides and iron-based compounds, have shown considerable promise, delivering competitive performance without the ethical and supply chain issues associated with cobalt. Global research efforts have made significant strides in overcoming the technical barriers to SIB commercialization. Collaborative projects across North America, Europe, and Asia are accelerating the development of scalable synthesis techniques and the optimization of material properties. These efforts are particularly focused on improving the ionic conductivity and ensuring the structural integrity of cathodes during cycling. The integration of advanced characterization techniques has also played a pivotal role in understanding the mechanisms at play, guiding the design of next-generation materials. As SIB technology continues to evolve, its potential applications in large-scale energy storage particularly for grid stabilization are becoming increasingly apparent. The combination of abundant raw materials, improved cathode performance through doping, and the shift toward cobalt-free compositions positions SIBs as a strong contender in the energy storage market. This review highlights the progress made and the challenges that remain, outlining future directions for research and development that will be crucial in transitioning SIBs from the laboratory to real-world applications.