N-Doped 3D Interconnected Carbon Bubbles as Anode Materials for Lithium-Ion and Sodium-Ion Storage with Excellent Performance

In this paper, we develop a novel N-doped 3D interconnected carbon bubbles (NCBs) by a facile method of nitric acid extraction precursor at room temperature for the lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). The NCBs with hollow carbon bubbles having a size of ~100 nm interconnected to each other exhibits high specific surface area and abundant active sites, which ensures continuous diffusion paths for ions and electrons and keeps the electrode structure more stable, thus significantly enhancing the lithium-ion and sodium-ion storage capability. In lithium-ion batteries, the NCBs electrode shows a high reversible capacity of 1180 mA h g−1 after 380 cycles at a current density of 1 C. As the current density increased from 1 to 10 C, the capacity still retains 407.1 mA h g−1. While in sodium-ion batteries, the NCBs electrode provides a capacity of 222.5 mA h g−1 after 200 cycles at a current density of 50 mA g−1. And the capacity maintains at 107.5 mA h g−1 even the current density increased from 0.05 to 5 A g−1. The excellent cycling performance and high-rate capability should be attributed to the synergistic effect of the 3D interconnected hollow structure and the incorporation of nitrogen atoms.