Magneto-Responsive Hybrid Layered Double Hydroxides With Improved Electrochemical Performance and Field-Actuated...

Overcoming the intrinsic transport limitations of hybrid supercapacitors using magneto stimulus-responsive layered double hydroxide (LDH) materials is a promising strategy. Here, we present an urchin-like Ni-Co LDH@CNT hybrid that exhibits extraordinary field-enhanced capacitance under a relatively low magnetic field-strengths. The presence of Ni²⁺/Ni³⁺ and Co²⁺/Co³⁺ allows fast electron hopping and increases the magnetic coupling, while the defects-rich CNTs promote charge delocalization and fast charge transfer. The magnetohydrodynamic microconvection induced by Lorentz forces enhances the ion permeation and surface-controlled redox activity at the hybrid interface. The ion diffusion coefficient increases 2.3-fold (∼6.53 × 10^-13 cm² s^-1), while the Tafel slope declined from 77.62 to 62.23 mV dec^-1 under field, signifying faster reaction kinetics. The Ni-Co LDH@CNT delivers a high-specific capacity of 657.8 mC cm^-2 at 1 mA cm^-2 with 78.2% improvement over zero-field conditions and retains ∼98% capacity retention even after 3000 cycles. Magnetic measurements reveal that the 60 mT cycled electrode shows high saturation magnetization of 1.74 emu g^-1 compared to the zero-field (1.45 emu g^-1), indicating an increased spin alignment and stronger magnetic coupling that facilitates electron transport and redox activity. An asymmetric hybrid device prototype demonstrates reversible field-driven capacity recovery over 10 000 cycles, illustrating magnetically induced self-recovery behavior.