Effect of oxygen-containing functional groups at SWCNT on the formation of sodium and lithium dendrites

To realize high-performance and safe metal anodes for rechargeable Na/Li metal batteries, it is necessary to explore how various oxygen-containing groups on carbon nanotubes surface affect Na and Li (Na/Li) dendrites growth. Hence, the adsorption behavior of the Na/Li atom and Na/Li dendrites formation on various oxygen-containing groups (-COOH, -OH, -CO, -COO, -O-) decorated SWCNTs (O-SWCNTs) were investigated by density functional theory (DFT) calculations. Compared with intrinsic SWCNT, the groups on SWCNT promote the adsorption of Na/Li because O is more electronegative than C. The adsorption strength of Na/Li and Na2/Li2 on different O-SWCNTs depends on the electron-accepting ability of the active O atom of the groups. The result shows that only OH-SWCNT can serve as a promising current collector for the development of dendrite-free Na/Li metal batteries due to its relatively weak attraction for the second Na/Li. On the other O-SWCNTs, Na and Li dendrites can be formed through NaO and LiO bond respectively. Therefore, dendrite-free carbon tubes collector can be achieved by regulating the oxygen-containing groups on its surface. Overall, this work brings new inspiration to the preparation of collectors to avoid dendrite growth.