Assembly of Aqueous Rechargeable Magnesium Ions Battery Capacitor: The Nanowire Mg-OMS-2/Graphene as Cathode and Activated Carbon as Anode

The aqueous magnesium ion battery (AMIB) system is an attractive candidate in the aqueous batteries due to its high safety properties, similar electrochemical characteristics to lithium and low cost in energy storage applications. The magnesium octahedral molecular sieves of Mg-OMS-2 and the Mg-OMS-2/Graphene composite, depending on their unique 2 x 2 tunnel structure that can provide enough large pore size for magnesium ions insertion/deinsertion into/from the lattice of host materials, are utilized as the cathode materials in the AMIB system and exhibit good battery performances in the three different magnesium salt electrolytes. The Mg-OMS-2/Graphene, not only maintaining the tunnel structure but also possessing the excellent electrochemical property, obtains better rate ability and cycle performance than that of Mg-OMS-2. Furthermore, the Mg-OMS-2/Graphene//AC system is first assembled as aqueous rechargeable magnesium ion battery capacitor. The discharge capacity of this system remains to be 44.1 mAh g(-1) at the current density of 100 mA g(-1) after 500 cycles and the capacity retention rate is 95.8%.