Combining Janus Separator and Organic Cathode for Dendrite-Free and High-Performance Na-Organic Batteries

The growth of Na-dendrites and the dissolution of organic cathodes are two major challenges that hinder the development of sodium-organic batteries (SOBs). Herein, a multifunctional Janus separator (h-BN@PP@C) by using an interfacial engineering strategy, is proposed to tackle the issues of SOBs. The carbon layer facing the organic cathode serves as a barrier to capture dissolved organic materials and enhance their utilization. Meanwhile, the h-BN layer facing the Na anode possesses high thermal conductivity and mechanical strength, which mitigates the occurrence of localized-temperature “hot spots” and promotes the formation of a NaF-enriched SEI, thereby suppressing dendrite growth. Consequently, the Janus separator enables a stable Na plating/stripping cycling for 1000 h at 3 mA cm⁻². Equipped with the Janus separator, organic cathodes including dibenzob,i]thianthrene-5,7,12,14-tetraone (DTT), pentacene-5,7,12,14-tetrone and Calix4]quinone cathodes demonstrate high capacity and remarkable cycling performance. In particular, the DTT exhibits a bipolar co-reaction storage mechanism and achieves an ultrahigh capacity (≈342.6 mAh g⁻¹), long-term cycling stability (capacity decay rate of 0.15% per cycle over 550 cycles at 500 mA g⁻¹) and fast kinetics (1000 mA g⁻¹≈2.8 C). This study offers a straightforward, effective, and promising solution to address the challenges in SOBs.