Dendrite-suppressed Li deposition enabled by surface-tailored carbon-based current collectors for high-rate and stable Li-metal batteries

Lithium (Li)-metal batteries (LMBs) are considered as one of the most promising next-generation batteries due to the exceptionally low redox potential and high specific capacity of the Li metal anode. However, their practical application remains challenging due to problems such as Li dendrites growth and poor Coulombic efficiency (CE) during cycling. Among the various approaches proposed to solve these challenges, the introduction of 3D current collectors has been proven effective for suppressing the growth of dendritic Li. Nevertheless, the surface properties of 3D current collectors have been somewhat overlooked in existing studies. In this work, we assessed three distinct carbon nanotube (CNT)-based current collectors (namely, CNT, oxidized CNT (ONT), and reduced ONT (rONT)) to investigate the effects of their surface properties and compositions on the Li deposition process and, hence, the electrochemical stability of the resulting LMBs. The pristine CNT-based current collector exhibits a poor electrolyte wettability, thus resulting in a rapid decline in CE over successive cycles. In contrast, the ONT current collector shows enhanced electrolyte wettability with lithiophilic surface, which significantly improves the interfacial kinetics and cycling stability. Moreover, after the subsequent reduction process, the rONT current collector exhibits a higher electrical conductivity than the ONT current collector while maintaining the favorable electrolyte wettability. Consequently, the Li|rONT cell delivers a more stable cycling performance than the Li|ONT cell at high current densities. These results demonstrate that the electrochemical performances of the LMBs can be significantly improved by suitably modifying the surface characteristics of the current collectors.