Tailoring Ion-Transport Networks for Wide-Temperature Mg-Organic Batteries

Developing high-performance magnesium metal batteries is hindered by sluggish Mg2+ diffusion kinetics and the structural instability of conventional cathodes. Here, we propose a design principle for organic cathodes by regulating polymer spatial configurations, which facilitates multidirectional Mg2+ transport and enhances structural robustness. Three poly(perylene diimide) (PDI)-based polymers, namely linear pPDI, zigzag mPDI, and layered oPDI, were synthesized to systematically investigate the structure-function relationship. The oPDI cathode, featuring a highly ordered two-dimensional layered configuration, forms an interconnected three-dimensional Mg2+ transport network, in striking contrast to the one-dimensional interchain hopping confined in pPDI and mPDI. By integrating multiscale experimental characterizations with density functional theory calculations, we reveal that oPDI enables rapid Mg2+ diffusion, minimizes structural distortion, and exhibits highly reversible carbonyl redox chemistry. Consequently, oPDI exhibits enhanced rate capability, durable cycling performance (92% retention over 1000 cycles), and wide-temperature adaptability from -20 to 50 °C. Furthermore, Mg||oPDI pouch cells also maintain stable cycling performance, demonstrating the potential for practical implementation. This work presents spatial configuration engineering as an effective strategy for designing high-performance organic cathodes and advances the development of safe, scalable, and temperature-resilient magnesium batteries.