Synergistic effect of MXene and Co3O4 nanoneedles: Constructing high-performance lithium-ion capacitor anodes

MXenes exhibit a distinctive two-dimensional (2D) open-layered architecture, characterized by an extensive specific surface area, abundant surface functional groups, and excellent electrical conductivity, rendering them a promising candidate for the anode material in lithium-ion capacitors (LICs). However, the inherent tendency of MXenes towards interlayer restacking and structural degradation severely impedes ion transport kinetics, leading to compromised electrochemical performance. To address this issue, a straightforward hydrothermal synthesis strategy was proposed for fabricating porous Co 3 O 4 nanoneedle/MXene composites via in-situ grown self-assembly. The two-dimensional layered structure, high electrical conductivity, and abundant surface functional groups of MXene enable efficient ion intercalation, while Co 3 O 4 contributes enhanced theoretical capacity and rich oxidation states. These two components form a mutually supportive synergistic effect. This synergy not only shortens the ion/electron transport pathways within the MXene matrix but also mitigates the agglomeration and volume expansion phenomena associated with the Co 3 O 4 nanoneedles. Therefore, the obtained Co 3 O 4 MXene electrode maintained a specific capacity of 632 mA h g −1 after 1000 cycles at a high current density of 1 A g −1 , far exceeding the original MXene electrode. Assembled with activated carbon to form Co 3 O 4 nanoneedles/MXene//AC lithium-ion capacitors (LIC), achieving a high energy density of 254 Wh k g −1 and a maximum power density of 4000 W kg −1 . The excellent performance of the porous and porous Co 3 O 4 nanoneedle/MXene composite reflects its potential as a high-performance anode material for LIC.