In situ growth of hydrophilic nickel-cobalt layered double hydroxides nanosheets on biomass waste-derived porous carbon for high-performance hybrid supercapacitors

Rational design and cost-effective fabrication of layered double hydroxides (LDHs) nanosheets with extraordinary electrochemical performance is a key challenge for hybrid supercapacitors (HSCs). Herein, we report a facile in situ growth methodology to eco-friendly synthesize hydrophilic NiCo-LDHs nanosheets on biomass waste-derived porous carbon (BC) for robust high-performance HSC cathode. The in situ growth process under ultrasonication realizes the rational arrangement of NiCo-LDHs nanosheets on the surface of BC, which effectively increases the specific surface area, promotes the electronic conductivity and enhances the wettability of NiCo-LDHs nanosheets without affecting their thickness values. With the beneficial effects of ultrathin thickness of LDHs nanosheets (6.20 nm), large specific surface area (2324.1 m² g⁻¹), low charge transfer resistance (1.65 Ω), and high wettability with electrolyte (34°–35°), the obtained Ni₂Co₁-LDHs/BC50 electrode possesses an ultra-high specific capacitance of 2390 F g⁻¹ (956 C g⁻¹) at 1 A g⁻¹, which is superior to most reported values. Furthermore, an assembled Ni₂Co₁-LDHs/BC50//YP-80F HSC delivers a maximum specific energy of 52.47 Wh kg⁻¹ at 375 W kg⁻¹, and maintains a high capacitance retention of 75.9% even after 4000 cycles. This work provides a facile approach to fabricate LDHs nanosheets based cathode materials for high-performance HSCs.