Architecture-Interface Co-Design of g-C₃N₄ Driven Dry Thick Cathodes Enabling Fast Li-Ion Transport

Overcoming ionic transport limitations in thick-film electrodes is a central challenge for next-generation high-energy-density lithium-ion batteries. Here, we report an architecture-interface co-design strategy for solvent-free dry thick cathodes, introducing nanostructured graphitic carbon nitride (g-C₃N₄) as a multifunctional ion-transport promoter, representing the first demonstration of its application as a cathode additive. Mechanistic studies reveal that g-C₃N₄ operates via a dual mechanism, simultaneously enhancing electrolyte wettability and accelerating Li⁺ transport kinetics through transient Li-N coordination that effectively lowers the desolvation energy barrier. High-resolution 3D X-ray nanotomography and pore network modeling quantitatively map the ionic-mechanical trade-off arising from compressive spring-back in the dry process, directly guiding the optimization of electrode architecture. The resulting single-layer dry electrode (∼21.5 mg cm^-2, ∼68 µm thick) delivers a 165.9% capacity increase at 3C and a 2.85-fold enhancement in power density, while achieving markedly improved cyclic stability with 81.3% capacity retention after 600 cycles. Furthermore, a functionally graded dual-layer design (∼42.2 mg cm^-2, ∼113 µm thick) yields a 62.5% capacity gain at 1C. This work establishes a generalizable, scalable, and sustainable pathway for engineering high-performance dense electrodes.