Stable polyaniline-based cathode material enabled by MgMn2O4 for aqueous magnesium-ion batteries: Experimental and DFT study

Aqueous rechargeable magnesium ion batteries (ARMIB) are an attractive option for replacing lithium-ion batteries because magnesium is abundant and easily accessible in the earth's crust, making it a viable alternative for energy storage. The development of practical ARMIB is also hindered by the lack of advanced electrode materials, as the slow diffusion rate of magnesium ions in solids limits their performance. In this research, we successfully developed a cathode based on composite of MgMn₂O₄ (MMO) and polyaniline (PANI) for ARMIB that achieves high energy density, stability and reversibility. The successful synthesis and the desired structure were examined using X-ray diffraction and scanning electron microscopy. The MgMn₂O₄/Polyaniline (MMP 5:1) composite, which MMO is 5 times PANI, cathode can achieve high discharge capacities of 232 mA h g⁻¹ at a current density of 500 mA g⁻¹ and extraordinary long-term cycling stability with 73 % capacity retention after 250 cycles. Furthermore, density functional theory and computational details were conducted to monitor the Mg storage process, migration energy barrier of ions and electronic properties of structure.