Rechargeable Aqueous Zinc–Manganese Dioxide/Graphene Batteries with High Rate Capability and Large Capacity

Batteries based on Zn and other two-valent metals can be nearly ideal charge storage devices because of their high energy density combined with reliability, earth-abundance, and low flammability. Searching for high-performance positive electrodes with good rate capability and adequate cycle life is currently a hot topic and a great challenge for developing zinc batteries. Here, a binder-free 3D porous graphene aerogel-supported α-MnO2 cathode (G-MnO2) is synthesized via a facile and scalable hydrogel method. The hybrid cathode of α-MnO2 nanotube attached on highly conductive interconnected graphene frameworks enables rechargeable Zn/G-MnO2 batteries with a high capacity of 321 mAhg–1 at 0.2C (1C = 240 mAhg–1), good rate capability, and ultralong cycle life (91% capacity retention over 300 cycles at a high current rate 3C). These findings open the pathway to a large family of low-cost high-performance Zn-batteries and potentially other two-valent metals for a wide range of applications.