Optimized Cathode for High‐Energy Sodium‐Ion Based Dual‐Ion Full Battery with Fast Kinetics

Abstract The most used systems based on the graphite‐based cathode show unsatisfactory performance in dual‐ion batteries. Developing new type cathode materials with high capacity for new type anions storage is an effective way to improve the total performance of dual‐ion batteries. Herein, a protonated polyaniline (P‐PANI) cathode is prepared to realize efficient and stable storage of ClO₄^–, and a high reversible capacity of 143 mAh g⁻¹ at 0.2 A g⁻¹ after 200 cycles can be obtained, which is competitive compared with common graphite cathodes. In addition, the highly reversible coordination storage mechanism between ClO₄⁻ and P‐PANI cathode is indicated, rather than the labored intercalation reactions between PF₆⁻ and graphite. Subsequently, a full cell (P‐PANI//N‐PDHC) fabricated with a P‐PANI cathode and hard carbon anode (N‐PDHC) can deliver a high energy density of 284 Wh kg^–1 for 2000 cycles at 2 A g^–1, and the relevant pouch‐type full cell can easily power a smartphone. In general, this work may promote the exploitation of sodium‐based dual‐ion batteries in practical application.