An eco‐friendly Na‐ion battery utilizing biowaste‐derived carbon and birnessite with enhanced high voltage reaction
Gregorio F. Ortiz, Ruqin Ma, Mingzeng Luo, Yixiao Li, Zhanning He, Yu Su, Jiale Huang, Yong Yang, Zhanhua Wei
Abstract
Abstract Trigonal birnessite (Na 0.5 MnO 2 ·0.7H 2 O) with quasi‐hexagonal‐stacked particles is synthesized by a simple procedure. The MnO 6 layers are expanded (ca. 7.1 Å as confirmed by HRTEM) by sodium ion and water molecules permitting the cyclability of the cathode up to 4.4 V without anionic redox effect. This particular phase exhibits sodium storage performance with 181.2 mA h g −1 reversible capacity, high Coulombic efficiency (99.8%), good rate performance (20–640 mA g −1 ), and 80% capacity retention over 200 cycles. X‐ray adsorption near‐edge structure (XANES) spectra at Mn‐k edge confirmed that the main redox component is Mn 3+ /Mn 4+ . An environmental‐friendly Na‐ion full cell is assembled with this cathode and biowaste‐derived carbon (obtained from trash of lemon peels) anode and provided ∼ 330 Wh kg −1 energy density (at the material's level) which is preserved at ∼71% over 200 cycles. Manganese, sodium, and carbon are cheap and eco‐friendly materials for practical energy storage eagerly sought after in the industry.