High FeLS(C) electrochemical activity of an iron hexacyanoferrate cathode boosts superior sodium ion storage

• Published in: Carbon energy 2023-05, Vol.5 (5), p.n/a
• Main Authors: Guo, Junhong, Feng, Fan, Zhao, Shiqiang, Shi, Zhenhai, Wang, Rui, Yang, Meng, Chen, Fangfang, Chen, Suli, Ma, Zi‐Feng, Liu, Tianxi
• Format: Article
• Language: English
• Subjects: cathode material; electrochemical activity; sodium iron hexacyanoferrate; sodium‐ion batteries; structural evolution
• ISSN: 2637-9368; 2637-9368
• DOI: 10.1002/cey2.314

Sodium iron hexacyanoferrate (FeHCF) is one of the most promising cathode materials for sodium‐ion batteries (SIBs) due to its low cost theoretical capacity. However, the low electrochemical activity of FeLS(C) in FeHCF drags down its practical capacity and potential plateau. Herein, FeHCF with high FeLS(C) electrochemical activity (C‐FeHCF) is synthesized via a facile citric acid‐assisted solvothermal method. As the cathode of SIBs, C‐FeHCF shows superior cycling stability (ca. 87.3% capacity retention for 1000 cycles at 10 C) and outstanding rate performance (ca. 68.5% capacity retention at 50 C). Importantly, the contribution of FeLS(C) to the whole capacity was quantitatively analyzed via combining dQ/dV and discharge curve for the first time, and the index reaches 44.53% for C‐FeHCF, close to the theoretical value. In‐situ X‐ray diffraction proves the structure stability of C‐FeHCF during charge–discharge process, ensuring its superior cycling performance. Furthermore, the application feasibility of the C‐FeHCF cathode in quasi‐solid SIBs is also evaluated. The quasi‐solid SIBs with the C‐FeHCF cathode exhibit excellent electrochemical performance, delivering an initial discharge capacity of 106.5 mAh g−1 at 5 C and high capacity retention of 89.8% over 1200 cycles. This work opens new insights into the design and development of advanced cathode materials for SIBs and the beyond. An ultrahigh rate and long cycling life FeHCF cathode with high FeLS(C) electrochemical activity was successfully achieved via a facile citric acid‐assisted solvothermal method, where it delivers a discharge capacity of 122.6 mAh g−1 with a capacity retention of 87.3% at 10 C over 1000 cycles. The high contribution of FeLS(C) to the whole capacity was quantitatively analyzed.