Self-supporting heteroatomic S/N co-doped carbon scaffold for robust lithium metal anodes

Abstract

Lithium-metal is seen as a perfect anode for upcoming rechargeable batteries. However, unchecked formation of lithium-dendrites poses a risk of puncturing the separator, potentially leading to thermal runaway. Additionally, lithium-metal anodes experience significant volume changes during cycling, a consequence of their “host-free” nature. To tackle these challenges, we have designed a sulfur/nitrogen co-doped graphene-based carbon-skeleton interlaced with multi-walled carbon-nanotubes (S/N-rGO/MWCNTs), serving as a self-supporting 3D current-collector for lithium-metal anodes. The S/N doping significantly enhances the lithiophilic properties of the graphene-based carbon materials, thereby promoting the even distribution of lithium-metal deposition, which is verified by density functional theory computational analysis and microscopy observation. As-obtained graphene-based skeleton material can inhibit the growth of lithium-dendrites by modulating local current density over the electrode. Consequently, the S/N-rGO/MWCNTs have demonstrated remarkable charge/discharge performance featuring elevated Coulombic efficiency of 96.8 % at 1 mA cm⁻² for 1 mAh cm⁻² and 94.9 % at 3 mA cm⁻² for 1 mAh cm⁻² over 500 cycles, respectively. The symmetrical batteries showcased a remarkable cycling life of approximately 1200 h at 1 mA cm⁻² and 1 mAh cm⁻² with minimal polarization (∼12 mV). This innovative S/N-rGO/MWCNT current-collector with enhanced performance marks a notable progress in lithium-metal anode technology.