MnO ₂ Nanocoils/GN/SWCNT Composites as an Electrode Material for Sodium Energy Storage

Manganese‐based materials, such as manganese dioxide (MnO 2 ), exhibit a substantial potential as electrode materials for sodium‐ion batteries (SIBs) owing to their favorable electrochemical characteristics. Herein, an integrated strategy coupling manganese oxides with three‐dimensional graphene/single walled carbon nanotubes (3D GN/SWCNTs) is proposed to simultaneously optimize specific surface area and charge transport efficiency. MnO 2 nanocoils/GN/SWCNT composites were successfully synthesized. On the basis of as‐obtained products with a regular morphology, systematic electrochemical performances of MnO 2 nanocoils/GN/SWCNT composites were evaluated in cells with two electrolytes of sodium hexafluorophosphate (NaPF 6 ) based electrolyte and sodium perchlorate (NaClO 4 ) based electrolyte, paired with two current collectors of titanium (Ti) and copper (Cu) thin sheets. The optimized SIB configuration (MnO 2 nanocoils/GN/SWCNT electrode materials, NaClO 4 ‐based electrolyte, and Ti thin sheet current collector) delivered an initial discharge capacity of 1021.88 mAh g −1 , the second‐cycle reversible capacity of 234.78 mAh g −1 , and a capacity retention of 120.66 mAh g −1 after 500 cycles at a current density of 100 mA g −1 . In addition, the in situ X‐ray diffraction technology and cell disassembled analyses are used to explore the reversible energy storage process. In summary, the MnO 2 nanocoils/GN/SWCNT composites demonstrate a stable cycling performance, offering novel morphological perspectives for designing high‐performance SIB materials.