Study on the morphologies and electrochemical properties of the iron oxalate/graphene sheet composite with different polymorphs

• Published in: Materials letters 2019-03, Vol.238, p.187-190
• Main Authors: Zhang, Keyu, Li, Yin, Wang, Yunke, Yuan, Meimei, Dai, Yongnian, Yao, Yaochun
• Format: Article
• Language: English
• Subjects: Anodes; Chemical synthesis; Crystal structure; Electrochemical analysis; Electrode materials; Energy storage and conversion; Graphene; Graphene sheet; Hydrogen bonds; Iron; Iron oxalate; Lithium-ion batteries; Materials science; Morphology; Particulate composites; Phase transformation
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/j.matlet.2018.12.008

•FeC2O4/Gs composites with different crystal polymorphs were prepared by controlling synthesis temperature.•The α-FeC2O4/Gs exhibits a superior reversible special capacity and better capacity retention.•Crystal structure design of oxalate-based anode materials is a new way on modifying of irreversible capacity. Iron oxalate/graphene sheet (FeC2O4/Gs) composites with different crystal polymorphs were prepared through simple solvothermal reaction by controlling synthesis temperature. The effect of crystal structure on the morphology and the electrochemical performance was investigated. The results show that the structure and morphology are strikingly different in both phases. The β-FeC2O4·2H2O/Gs is composed with irregular shaped of nanometer sized rod and sheet particles. In contrast, the composite of α phase is the micron polygonal prism structure which is due to the reordering of hydrogen bonds between inter layer, resulting in excellent electrochemical performance: 916.49 mAh g−1 for the reversible specific capacity, a retention of 66.9% after 50 cycles and nearly 550 mAh g−1 after 200 cycles at 1 C. This work provides a new way for oxalate-based anode materials to modify initial irreversible capacity and improve capacity retention.