Explanation of polyimide as a green electrode material for Mg-, Na- and Li-ion batteries: DFT and AIMD approach

In this work, Density Functional Theory (DFT) calculations were employed to investigate the polyimide application in Mg, Li, and Na-ion batteries (MIBs, LIBs, and SIBs). Band structure calculations demonstrate that Mg adsorption reduced the substrate’s band gap, while Li and Na adsorption transformed it from semiconducting to metallic. Theoretical capacities for MIBs/LIBs/SIBs were calculated at 183.56/734.27/458.92 mAh/g. The fully adsorbed complexes exhibited thermodynamic stability and thermal stability at 600 K. The average open-circuit voltages (OCV) for Mg/Li/Na were 0.15/0.81/0.78 V, respectively, falling within the appropriate voltage range for these batteries. Diffusion energy barrier analysis revealed no barrier for ions migrating around the carbonyl group. Additionally, Li and Na diffused along hexagonal rings with barriers of 0.39 eV and 0.14 eV, respectively. Zero-point energy (ZPE), Wigner, and Wigner-tunneling corrections indicated a tunneling effect for Li. These findings suggest polyimide as a viable anode material for high-capacity MIBs, LIBs, and SIBs.