High‐Performance Magnesium‐Organic Batteries Enabled by a Multielectron Redox‐Bipolar Polyaniline Cathode

Abstract Rechargeable magnesium batteries (RMBs) are emerging as a safer, high‐capacity alternative to lithium‐ion batteries due to the high volumetric capacity and reduced dendrite formation of magnesium anode. Among different cathodes of RMBs, bipolar‐type materials further enhance the energy density of RMBs by balancing high redox potential with specific capacity. Herein, the application of emeraldine base polyaniline (PANI) as a bipolar‐type cathode material for RMBs is explored. PANI exhibits both p‐ and n‐type charge storage behaviors, enabling a high specific capacity of 186.8 mAh g⁻¹ with stable cycling performance at the current density of 200 mA g⁻¹ and a high power density of 6341.8 W kg⁻¹ superior to traditional materials. First principle calculations and ex situ characterizations reveal that the molecular structure of PANI supports a bipolar charge storage mechanism. Additionally, the pouch cells based on PANI demonstrate reliable operation and flexibility, positioning PANI as a promising cathode for advanced RMBs and other energy storage systems.