Innovative 3D-printed transition metal-doped carbon xerogel monoliths as self-standing cathodes for Li-O2 batteries

Abstract

The growing energy demand driven by industrialization and the expansion of electronic devices has accelerated the development of next-generation rechargeable batteries. Among the promising strategies, the combination of carbon xerogels, which are versatile porous materials, with 3D printing technologies enables the design of tailored electrode architectures for advanced energy storage systems such as Li-O2 batteries. This study investigates monolithic carbon xerogels doped with transition metals like Cu, Fe, and Co, and exploits the ability of 3D printing to create straight-channel morphologies to improve the performance of Li-O2 batteries. A complete morphological, surficial, and electrochemical characterization was carried out. HAADF-STEM and EDX element mapping images confirmed the homogeneous distribution of metal nanoparticles within the carbon matrix. A detailed analysis explored the relationship between textural properties (measured with N2, CO2, and Hg), particle size, cracking behaviour, and electrical conductivity of the resultant materials. These structures were directly used as self-standing oxygen cathodes in Li-O2 batteries, presenting a novel and groundbreaking approach compared to traditional materials in the field. In long-term cycling tests with capacity limit to 10 h (a variable under study), the CX@Fe material achieved the longest cycling time (1000 h) with the lowest charge potential (<4 V), outperforming CX@Co (700 h), and significantly exceeding CX@Cu and CX electrodes. Finally, a successful reuse of the CX@Fe cathode was possible, reinforcing its viability as a sustainable solution for high-performance Li-O2 batteries.