Binder-free and flexible delta-MnO2@multiwalled carbon nanotubes as high-performance cathode material for aqueous magnesium ion battery

In order to develop a high-performance electrode material for aqueous magnesium ion battery (AMIB), we report a binder-free and flexible δ-MnO2@multiwalled carbon nanotubes on carbon cloth (δ-MnO2@MWCNTs/CC) composite by a simple hydrothermal method. The MnO2 nanoflakes are deposited on the surface of CC coated with high conductivity MWCNTs to form three-dimensional hierarchy architecture, which improves the electrochemical performances. The δ-MnO2@MWCNTs/CC electrode displays a discharge capacity of 246.7 mAh g−1 at a current density of 50 mA g−1 and its capacitance retention at a current density of 1000 mA g−1 can reach 80% after 2000 cycles. Furthermore, the AMIB system is assembled by δ-MnO2@MWCNTs/CC as cathode and activated carbon as anode, which dispays a discharge capacity of 72.4 mAh g−1 at 100 mA g−1. The δ-MnO2 with interlayer structure can provide sufficient space for the insertion/deinsertion of Mg2+ ions into/from the lattice of host materials without the change of phase. This work prepares a high-performance and flexible electrode material for low-cost AMIB system.