A High-Rate and Long-Life Aqueous Rechargeable Mg-Ion Battery Based on an Organic Anode Integrating Diimide and Triazine

Abstract

Aqueous Mg-ion batteries (MIBs) lack reliable anode materials. This study concerns the design and synthesis of a new anode material - a π-conjugate of 3D-poly(3,4,9,10-perylenetracarboxylic diimide-1,3,5-triazine-2,4,6-triamine) [3D-P(PDI-T)] - for aqueous MIBs. The increased aromatic structure inhibits solubility in aqueous electrolytes, enhancing its structural stability. The 3D-P(PDI-T) anode exhibits several notable characteristics, including an extremely high rate capacity of 358 mAh g^-1 at 0.05 A g^-1 , A 3D-P(PDI-T)‖Mg₂ MnO₄ full cell exhibits a reversible capacity of 148 mAh g^-1 and a long cycle life of 5000 cycles at 0.5 A g^-1 . The charge storage mechanism reveals a synergistic interaction of Mg²⁺ and H⁺ cations with C-N/C=O groups. The assembled 3D-P(PDI-T)‖Mg₂ MnO₄ full cell exhibits a capacity retention of around 95 % after 5000 cycles at 0.5 A g^-1 . This 3D-P(PDI-T) anode sustained its framework structure during the charge-discharge cycling of Mg-ion batteries. The reported results provide a strong basis for a cutting-edge molecular engineering technique to afford improved organic materials that facilitate efficient charge-storage behavior of aqueous Mg-ion batteries.

Keywords: Mg-ion batteries; charge storage; kinetics; organic electrodes; pseudocapacitors.