High-Performance and Low-Cost Manganese Oxide/Multiwalled Carbon Nanotubes Composite as Cathode Material for Aqueous Magnesium Ion Battery

Abstract

The aqueous magnesium ion batteries (AMIBs) with the advantages of low cost, intrinsical safety and environmentally friendly have received worldwide attention as promising candidates for green energy storage system. Herein, we report a composite material engineered from λ-MnO2 particles and multiwalled carbon nanotubes (MWCNTs) as cathode for AMIB. The λ-MnO2 possesses a spinel-type crystalline structure, which is beneficial for the insertion/deinsertion of Mg2+ ions. The MWCNTs network shorts ionic diffusion distance and increases the interface of electrode material/electrolyte. Hence, the λ-MnO2/MWCNTs composite demonstrates a large capacity of 251 mA h g-1 at 50 mA g-1 in 0.5 M Mgcl2 solution, and high capacity retention of 86.2% after 1000 cycles at 1000 mA g-1 in MgSO4 solution. Furthermore, the λ-MnO2/MWCNTs//AC system is firstly assembled as full AMIB, which delivers a specific capacity of 84.8 mA h g-1 at 100 mA g-1. The rate capability test is performed at 300 mA g-1. This system displays a gradually rise tendency in the specific capacity at initial 100 cycles on account of the activation process. After 1000 cycles, the specific capacity is 56.9 mA h g-1. This work develops an easily prepared, low-cost and good performance electrode material for AMIB system.