Renewable energy sources such as solar, wind, geothermal, and hydropower are crucial for minimizing our dependence on nonrenewable energy. To achieve a sustainable future, we need cost-effective and efficient electrical energy storage and conversion technologies for intermittent renewable energy sources.
The growing demand for reliable and eco-friendly power sources has boosted the popularity of rechargeable batteries. High-performance electrochemical batteries with high energy density are increasingly in demand as they offer a long-lasting and efficient power source. Researchers are currently working on developing safer and more environmentally friendly battery chemistries with higher energy densities and longer lifetimes to overcome the limitations of rechargeable lithium-ion batteries. Sodium-ion batteries, which are safer and more affordable than lithium-ion batteries, can use suitable electrode materials such as layered oxides, polyanionic compounds, and Prussian blue (PB) analogs. Among these, layered oxide cathode materials are promising for sodium-ion batteries as they offer low cost, non-toxicity, relatively high energy density, and safety during shipping due to the use of aluminum anode current collectors.
In this study, we investigated the synthesis of cathode materials for Sodium-ion batteries through mechanochemical and solid-state methods in the Na-Mn-O system and analyzed the structural, physical, and electrochemical properties of the as-synthesized materials. Na2Mn3O7 was synthesized through solid-state synthesis method, which involved annealing NaNO3 and MnCO3 at 600°C for 4 hours. This material exhibits impressive electrochemical performance, as it can maintain a capacity of 140-160 mAh/g even after subsequent cycles.
Na4Mn2O5, which is not well known for battery applications and is unstable in air, is difficult to obtain in powder form and has undergone a series of syntheses. The synthesis requires careful attention to impurities such as NaxMnO2 families, particularly β-NaMnO2 and α-NaMnO2. Due to its sensitivity to air or moisture, requires synthesizing in a controlled environment. A solid-state synthesis method that involved heating a mixture of N2O and Mn2O3 at 640 °C and annealing for 10 h in a quartz-sealed tube was developed. This resulted in a phase percentage of 93.51 %, which is the highest ever achieved.
Electrochemical test was performed on Na4Mn2O5 mixed with 50% carbon black. Galvanostatic charge/discharge test was carried out at C/50 current rate, the charging and discharging processes showed specific peaks and plateaus, indicating a pattern in the battery's behavior and capacity decline during the early charge and discharge processes.
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