Boosting the Zn-ion storage capability of birnessite manganese oxide nanoflorets by La3+ intercalation

Abstract

To develop aqueous rechargeable Zn-ion batteries (ZIBs) with high capacity and good rate capability, the focus is on cathode improvement. Herein, birnessite δ-MnO₂ nanoflorets with La³⁺ intercalation (LMO) were reported as high-energy and high-rate cathodes for ZIBs. The intercalation of La³⁺ within the δ-MnO₂ nanoflorets was readily achieved by a simple, scalable and effective precipitation process. Benefiting from the larger interlamellar spacing, reduced Zn²⁺ (de)insertion resistance and increased surface area after La³⁺ intercalation, the Zn-ion storage capability of the δ-MnO₂ nanoflorets was significantly boosted, resulting in high reversible capacity of 278.5 mA h g⁻¹ at 100 mA g⁻¹ and superb rate capability of 121.8 mA h g⁻¹ at 16-fold higher current density (only 3.4 mA h g⁻¹ for pristine δ-MnO₂ nanoflorets) as well as good durability. Moreover, the maximum energy and power densities of the as-obtained Zn//LMO battery reached 375.9 W h kg⁻¹ and 4.8 kW kg⁻¹ (based on the cathode mass), respectively. Considering the new design of La³⁺ intercalation, this study hopes to provide an insightful guide for exploring next-generation Mn-based cathode materials for ZIBs.