In-Situ Triphasic Engineering of Few-Layer Borophene/Graphene Hybrid with a Binary MOF for Flexible and High-Performance Sodium-Ion Supercapacitor

Advancing high-performance, compact, and flexible energy storage devices is essential for the progress of next-generation wearable electronics. In this study, a ternary hybrid electrode is fabricated by integrating few-layered Borophene nanosheets with amine-functionalized reduced graphene oxide (Amine-rGO), followed by the in-situ growth of NiCo-MOF. The synthesized composite takes advantage of the rigidity and high surface area of Borophene, the pseudocapacitive behavior of NiCo-MOF, and the structural flexibility and electrical conductivity of amine-rGO to enhance overall electrochemical performance. A flexible interdigitated Na-ion hybrid capacitor is constructed employing the amine-graphene/Borophene (AGB) composite as the anode and AGB/NiCo MOF as the cathode, with a PVA–NaOH gel electrolyte. The device delivers an output of 1.4 V, reaching a high volumetric energy density of 4.92 mWh cm⁻³ at a power density of 78.3 mW cm⁻³, and sustains 1.85 mWh cm⁻³ at 1566.4 W cm⁻³. It retains 86% of its original capacitance after 20 000 cycles and remains electrochemically stable under repeated mechanical bending and twisting, highlighting its mechanical durability. Moreover, the device showcases practical functionality by lighting a red light-emitting diode (LED). This study establishes an efficient and scalable approach for employing few-layered Borophene nanohybrids in flexible Na-ion interdigitated supercapacitors with enhanced volumetric energy and power densities.