δ‐MnO2 Nanofibers: A Promising Cathode Material for New Aluminum‐Ion Batteries

• DOI: 10.1002/celc.202000425
• Publication Date: 2020-04-15T14:04:06Z
• Authors: Paloma Almodóvar; David A. Giraldo; Joaquín Chancón; Inmaculada Álvare...; María Luisa López
• Keywords: 02 engineering and technology; 0210 nano-technology; 7. Clean energy

Abstractδ‐MnO2 nanofibers, synthesized by using a simple, low‐cost sol‐gel method, showed high electrochemical performance as a cathode for rechargeable Al‐ion batteries (AIBs). δ‐MnO2 presented an initial discharge capacity of 59 mA h g−1 and stabilized at 37 mA h g−1 at a current rate of 100 mA g−1 after 15 cycles and for more than 100 cycles with almost a 99 % coulombic efficiency. Different plateaus in charge/discharge curves, consistent with CV peaks, revealed the Al‐ion insertion/deinsertion and the electrochemical stability of the battery. Moreover, different rate CV measurements revealed the pseudocapacitive behavior of δ‐MnO2 in AIBs. The obtained charge/discharge capacities are ten times higher than previous studies performed with this material. Ex situ Raman and high‐resolution TEM measurements in different charge/discharge states revealed structural information of δ‐MnO2 upon Al‐ion intercalation/deintercalation.