Crystal form modulation enables high-performance manganese dioxide cathode for aqueous zinc ion battery

Abstract

Manganese dioxide (MnO2) is a promising cathode candidate for advanced rechargeable Zn-ion batteries (ZIBs) owing to its low cost, high theoretical capacity and high output voltage. However, the poor stability and low practical capacity has greatly hampered its commercialization. Herein, we demonstrate a crystal form modulation strategy to enhance the capacity and cycling durability of commercial γ-MnO2 as robust ZIBs cathode material. By introducing new β-MnO2 crystal form with compact (1 × 1) tunnel structure after simple calcination, the γ- and β- co-existed MnO2 (denoted as m-MO) shows enhanced electrical conductivity and structural stability. Consequently, the m-MO cathode exhibits an excellent capacity of 273.6 mAh g–1 at 0.25 A g–1 with good cycle stability, much higher than the pristine γ-MnO2 cathode (156.7 mAh g–1). Furthermore, an aqueous ZIBs based on m-MO cathode delivers a large peak energy density of 349.1 W h kg–1 at 0.322 kW kg–1 and power density of 4.77 kW kg–1 at 123.01 W h kg–1. This work presents an effective crystal form modulation strategy to construct high-performance ZIBs cathodes based on commercial MnO2, which is highly potential for further commercial applications.