Synergistic effect of K<sup>+</sup>and PANI in vanadium oxide hydration by interlayer engineering boosts the ammonium ion storage
Xingyu Chen, Ziying Feng, Xueying Dong, Hanmei Jiang, Changgong Meng, Yifu Zhang
Abstract
Abstract Aqueous ammonium‐ion (NH 4 + ) hybrid supercapacitor (AA‐HSC), as a new type of energy storage device with great potential, is in the initial stage of rapid development. Based on its special energy storage mechanism, exploiting novel NH 4 + ‐hosting materials is still a great challenge. Herein, vanadium oxide hydration (VOH) tuned by interlayer engineering of K + /PANI co‐intercalation, named KVO/PANI, is designed for AA‐HSC. Intercalated PANI can shield interaction between NH 4 + and V–O layers to some extent and enlarge interlayer space, which improves the efficiency of reversible NH 4 + (de)insertion. However, K + enhances redox activity and electronic conductivity. The synergistic effect of co‐intercalation optimizes intercalation pseudocapacitive behavior during the (de)ammonization process, which is reported in NH 4 + storage for the first time. Theoretical calculations reveal that the lowered electron transport barrier and enhanced electronic conductivity improve NH 4 + kinetics and exhibit high capacitance for charge storage. The KVO/PANI can deliver the specific capacitance of 340 F g −1 at 0.5 A g −1 and retain 177 F g −1 at 10 A g −1 . Pairing with activated carbon, the AA‐HSC can achieve a decent energy density of 31.8 Wh kg −1 . This work gives inorganic/organic co‐intercalation that can enhance the NH 4 + storage of VOH by interlayer engineering. The strategy can be used to design other materials for aqueous energy storage systems.