δ‐MnO<sub>2</sub> Nanofibers: A Promising Cathode Material for New Aluminum‐Ion Batteries
Paloma Almodóvar, David Giraldo, Joaquín Chancón, I. Alvarez‐Serrano, Marı́a Luisa López
Abstract
Abstract δ‐MnO 2 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‐MnO 2 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‐MnO 2 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‐MnO 2 upon Al‐ion intercalation/deintercalation.