Flexible lithium-ion batteries (LIBs) have garnered significant attention as essential power sources for wearable and flexible electronic devices [1-6]. Despite the increasing interest, achieving optimal flexibility, mechanical stability, and high energy density in flexible LIBs remains a formidable challenge. This study explores the potential of molybdenum carbide (Mo₂C) [7] and vertically-oriented graphene nanowalls (VGNWs) as anode materials for Lithium-Ion batteries.

A bottom-up synthesis approach is employed, involving the deposition of Mo carbide nanostructures on VGNWs using chemical vapor deposition, magnetron sputtering, and thermal annealing processes, followed by in-situ carburization via thermal annealing, resulting in binder-free hybrid electrodes. The resulting Mo₂C/VGNWs hybrids exhibit exceptional structural durability, small particle size, and a porous configuration, promoting enhanced electron and ion accessibility at the electrode-electrolyte interface. SEM results demonstrate varied Mo carbide morphologies based on annealing time, while TEM analyses reveal uniformly anchored Mo₂C nanoparticles on VGNWs.

Electrochemical tests reveal that Mo₂C/VGNWs hybrids outperform VGNWs/Papyex® electrodes in lithium storage behavior. Evaluation of the Mo₂C/VGNW hybrid electrode as a LIB anode material demonstrates superior electrochemical performance compared to VGNWs/Papyex® electrodes. The Mo₂C/VGNW hybrid electrode exhibits a higher first discharge capacity (0.23 mA·h·cm⁻²) compared to VGNWs/Papyex® (0.11 mA·h·cm⁻²) at 1C scan rate. Furthermore, the Mo₂C/VGNW electrode maintains a reversible specific capacity of 0.005 mA·h·cm⁻² after 200 cycles, while the VGNWs/Papyex® electrode shows a significantly lower capacity of 0.001 mAh cm⁻² after the same cycles. The synergistic effects of Mo₂C nanoparticles and highly conductive VGNWs contribute to the superior electrochemical characteristics, positioning the Mo₂C/VGNWs hybrid structure as a promising candidate for high-performance and flexible energy storage devices.

Notably, the Mo₂C/VGNW hybrid electrode demonstrates a progressively increasing coulombic efficiency from 30% to 90.4% in the first 50 cycles, followed by stable performance. The dynamic interactions between Mo₂C nanoparticles and the highly conductive VGNW support contribute to the superior electrochemical performance. This study presents a promising synthesis approach for developing highly efficient and flexible energy storage devices through other carbide/VGNW hybrids.