Ni, Co bimetallic MOF of dual‐controlled by micro‐morphology and unit cell structure for biomass‐based self‐supporting energy storage device

Increasing the interlayer spacing of metal–organic frameworks (MOFs) through multi‐metal ion doping has emerged as an effective strategy to enhance electrolyte‐ion transport within the MOF unit cell, enabling the design of nickel‐based MOF materials with high capacity and energy density. In this work, a series of NiCo‐MOF‐ x ( x = 1–5) were synthesized by incorporating Co 2+ ions into Ni‐MOF. The introduction of Co 2+ modulated the unit cell structure and governed the stacking configuration of MOF nanosheets. At an optimal Ni/Co molar ratio of 4:1, the NiCo‐MOF‐2 sample demonstrates superior electrochemical performance, delivering a specific capacitance of 1238.6 F g −1 at 0.2 A g −1 . Subsequently, NiCo‐MOF‐2 was grown in situ on carbonized wood (CW) to fabricate a NiCo‐MOF@CW composite, which exhibits an areal capacitance of 4960 mF cm −2 at 0.6 mA cm −2 . An asymmetric supercapacitor (NiCo‐MOF@CW//AC) was assembled using NiCo‐MOF@CW as the positive electrode and activated carbon (AC) as the negative electrode. The device achieves an areal energy density of 1.88 mWh cm −2 at a power density of 2.88 mW cm −2 (1 mA cm −2 ), with 83.6% capacitance retention after 2000 charge–discharge cycles. Notably, two serially connected NiCo‐MOF@CW//AC devices successfully illuminate a red LED (operating voltage: 1.6–1.75 V) for 20 min. The multi‐metal ion doping strategy combined with binder‐free, self‐supporting electrode architecture presents a novel approach for synthesizing high‐performance energy storage materials.