Synergistic Ni(OH)₂@Li₄Ti₅O₁₂@B/N-doped graphene architecture: Pioneering high-energy hybrid supercapacitors with superior electrocatalytic performance

초록

The urgent need for sustainable, high-performance energy storage systems has intensified research into hybrid supercapacitors (HSCs) that reconcile the high energy density of batteries with the power density and cycling stability of supercapacitors. This study presents a novel Ni(OH)2@Li4Ti5O12@B/N co-doped graphene (NOH@LTO@BNG) composite as an advanced positive electrode material, paired with activated carbon (AC) as the negative electrode, to address these challenges. The composite harnesses Ni(OH)₂’s pseudocapacitance, Li₄Ti₅O₁₂’s structural resilience, and B/N co-doped graphene's superior conductivity and surface area. Electrochemical evaluations reveal a specific capacity of 2965.80C/g at 3 mV/s, declining to 1038.03C/g at 50 mV/s, with a 1.6 V potential window, and a maximum specific capacity of 4571 F/g at 1 A/g, retaining 50.06 % at 2.2 A/g. The HSC achieves 98 % capacity retention over 10,000 cycles, an energy density of 45 Wh kg−1 at 2050 W/kg, and a kinetic shift from diffusion- to capacitance-dominated charge storage. Additionally, the composite exhibits exceptional electrocatalytic hydrogen evolution reaction (HER) performance, with an overpotential of 57 mV at −10 mA/cm2, outperforming NOH (85 mV) and NOH@LTO (73 mV), and rivaling Pt/C (48 mV) with robust stability over 1000 cycles. These findings demonstrate the synergistic material design's efficacy, positioning NOH@LTO@BNG as a cost-effective, versatile solution for next-generation energy storage and electrocatalytic technologies, with significant implications for renewable energy integration. © 2025 Elsevier B.V.

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