Boosting Stability and Storage Capacity of Prussian White Cathodes Using Carbon Nanotube Composites in Sodium-Ion Batteries

This study presents a new cathode material for sodium-ion batteries (SIBs), specifically a Prussian white (Na₂MnFe(CN)₆) combined with carbon nanotubes (PW–CNT), synthesized using a chelating-agent-assisted co-precipitation technique to manage defect formation and enhance electrochemical stability. Traditional Prussian white cathodes used in SIBs face several issues such as excessive lattice defects, irreversible phase changes, and structural instability, which result in inconsistent performance. Our research introduces a novel method for synthesizing cathode materials by integrating carbon nanotubes (CNTs) and a chelating agent, which play crucial roles in regulating moisture levels during the formation process.<br/>Incorporating CNTs into the synthesis creates a conductive carbon framework that not only maintains the structural stability of the cathode but also improves its electrochemical properties by enabling more efficient electron and ion transport. The chelating agent used in the process helps control the moisture content, a critical factor that influences defect formation and the overall stability of the material.<br/>The electrochemical performance of the PW–CNT composite cathode was extensively evaluated in SIB setups. The cathode demonstrated an impressive reversible capacity of 133 mAh g^_-1 at a discharge rate of 10C, which is nearly 30% higher compared to conventional Prussian white cathodes and about 1.2 times greater than traditional Prussian blue cathodes. This substantial increase in capacity highlights the effectiveness of the combination of the Prussian white matrix with carbon nanotubes, further improved by the moisture-regulating properties of the chelating agent.<br/>Additional testing of the PW–CNT composite cathode in a coin-type full cell with a hard carbon anode showed outstanding long-term cycling stability, with the cathode retaining around 58% of its initial capacity after 1500 cycles at a 1C rate. This durability indicates the material's robustness and its potential for long-term energy storage applications.<br/>This research not only advances our understanding of how material composition, synthesis conditions, and electrochemical performance interact in battery technologies but also demonstrates the promise of the PW–CNT composite in significantly improving the reliability and efficiency of SIBs. By addressing the limitations of traditional Prussian white cathodes through advanced material engineering, this work lays the groundwork for future innovations in SIB technology, potentially leading to more efficient and sustainable energy storage solutions. The benefits of these advancements are broad, affecting applications such as electric vehicles, portable electronics, and grid energy storage, thereby underscoring the importance of cutting-edge cathode materials in the development of battery technology.<br/><br/>1. J. Song, L. Wang, Y. Lu, J. Liu, B. Guo, P. Xiao, J. J. Lee, X. Q. Yang, G. Henkelman and J. B. Goodenough, J. Am. Chem. Soc., 2015, 137, 2658–2664.<br/>2. L. Deng, J. Qu, X. Niu, J. Liu, J. Zhang, Y. Hong, M. Feng, J. Wang, M. Hu, L. Zeng, Q. Zhang, L. Guo and Y. Zhu, <i>Nat. Commun.</i>, 2021, <b>12</b>, 2167<br/>3. Y. Liu, D. He, Y. Cheng, L. Li, Z. Lu, R. Liang, Y. Fan, Y. Qiao and S. Chou, <i>Small</i>, 2020, <b>16</b>, e1906946<br/>4. S. Wheeler, I. Capone, S. Day, C. Tang and M. Pasta, <i>Chem. Mater.</i>, 2019, <b>31</b>, 2619–2626<br/>5. L. Wang, Y. Lu, J. Liu, M. Xu, J. Cheng, D. Zhang and J. B. Goodenough, Angew Chem. Int. Ed. Engl., 2013, 52, 1964–1967.<br/>6. B. Sambandam, M. H. Alfaruqi, S. Park, S. Lee, S. Kim, J. Lee, V. Mathew, J. Y. Hwang and J. Kim, ACS Appl. Mater. Interfaces, 2021, 13, 53877–53891.<br/>7. L. Wang, J. Song, R. Qiao, L. A. Wray, M. A. Hossain, Y. D. Chuang, W. Yang, Y. Lu, D. Evans, J. J. Lee, S. Vail, X. Zhao, M. Nishijima, S. Kakimoto and J. B. Goodenough, <i>J. Am. Chem. Soc.</i>, 2015, <b>137</b>, 2548–2554