Potassium ion pre-intercalated MnO2 for aqueous multivalent ion batteries
Zikang Xu, Ruiqi Ren, Hang Ren, Jingyuan Zhang, Jinyao Yang, Jiawen Qiu, Yizhou Zhang, Guoyin Zhu, Liang Huang, Shengyang Dong
Abstract
Abstract Manganese dioxide (MnO 2 ), as a cathode material for multivalent ion (such as Mg 2+ and Al 3+ ) storage, is investigated due to its high initial capacity. However, during multivalent ion insertion/extraction, the crystal structure of MnO 2 partially collapses, leading to fast capacity decay in few charge/discharge cycles. Here, through pre-intercalating potassium-ion (K + ) into δ-MnO 2 , we synthesize a potassium ion pre-intercalated MnO 2 , K 0.21 MnO 2 ·0.31H 2 O (KMO), as a reliable cathode material for multivalent ion batteries. The as-prepared KMO exhibits a high reversible capacity of 185 mAh/g at 1 A/g, with considerable rate performance and improved cycling stability in 1 mol/L MgSO 4 electrolyte. In addition, we observe that aluminum-ion (Al 3+ ) can also insert into a KMO cathode. This work provides a valid method for modification of manganese-based oxides for aqueous multivalent ion batteries. Graphical Abstract