Continuous phase modulation of molybdenum carbide nanomaterials toward enhanced Li+ storage performances

In the pursuit of sustainable energy solutions, lithium-ion capacitors are gaining attention for their balanced energy and power density. Transition metal carbides are emerging as promising candidates due to their unique physical and chemical properties. Traditional synthesis methods often involve high-temperature carbon reduction or the application of reducing agents, leading to uncontrollable reactions and the generation of large particle sizes in the resultant materials. To address these challenges, this study employs an organic-inorganic hybrid carbonization, where MoO₃ and C₂H₄N₄ are uniformly mixed and then subjected to high-temperature carbonization in Ar. By adjusting carbonization temperature, time, and the amount of C₂H₄N₄ added, different phase Mo-based carbides (Mo₂C/C, MoC/C) are synthesized. Lithium-ion half-cell tests indicate that both materials have similar specific capacities and rate capabilities. Ex-situ XRD characterization show no phase change in Mo₂C/C or MoC/C during Li⁺ insertion/extraction processes. Mo₂C/C//AC and MoC/C//AC devices were constructed, which provided energy densities of 36.33 and 51.54 W h kg⁻¹ at power density of 150 W kg⁻¹, and 10.67 and 13.67 W h kg⁻¹ at power density of 2.4 kW kg⁻¹, respectively. This successful synthesis of diverse Mo-based carbides provides new material options for enhancing LICs performance, contributing to the development of efficient energy storage systems.