Nanohybrids of BCN-Fe 1-x S for Sodium and Lithium Hybrid Ion Capacitors.

Hybrid ion capacitors (HIC) are receiving a lot of attention due to their potential to achieve high energy and power densities, but they remain insufficient. It is imperative to explore outstanding and environmentally benign electrode materials to achieve high-performing HIC systems. Here, a unique boron carbon nitride (BCN)-based HIC system that comprises a microporous BCN structure and Fe 1-x S nanoparticle incorporated BCN nanosheets (BNF) as cathode and anode, respectively is reported. The BNF is prepared through a facile one-pot calcination process using dithiooxamide (DTO), boric acid, and iron source. In situ, crystal growth of Fe 1-x S facilitates the formation of BCN structure through the creation of holes/defects in the polymeric structure. The first principle density functional (DFT) theory simulations demonstrate the structural and electronic properties of the hybrid of BCN and Fe 1-x S as compelling anode materials for HIC applications. The DFT calculations reveal that both BCN and BNF structures have excellent metallic characters with Li + storage capacities of 128.4 and 1021.38 mAh g -1  respectively. These findings are confirmed experimentally where the BCN-based HIC system delivers exceptional energy and power densities of 267.5 Wh kg -1 /749.5 W kg -1 toward Li + storage, which outweighs previous HIC performances and demonstrates favorable performance for Li + and Na + storages.