Functionalized Halloysite Scaffold Controls Sodium Dendrite Growth

Sodium metal is one of the most promising anodes for the prospective low-cost rechargeable batteries. Nevertheless, the commercialization of Na metal anodes remains restricted by sodium dendrite growth. Herein, halloysite nanotubes (HNTs) were chosen as the insulated scaffolds, and Ag nanoparticles were introduced as sodiophilic sites to achieve uniform sodium deposition from bottom to top under the synergistic effect. Density functional theory (DFT) calculation results demonstrated that the presence of Ag greatly increased the binding energy of sodium on HNTs/Ag (-2.85 eV) vs HNTs (-0.85 eV). Meanwhile, thanks to the opposite charges on the inner and outer surfaces of HNTs, faster Na+ transfer kinetics and selective adsorption of SO3CF3- on the inner surface of HNTs were achieved, thus avoiding the formation of space charge. Accordingly, the coordination between HNTs and Ag afforded a high Coulombic efficiency (about 99.6% at 2 mA cm-2), long lifespan in a symmetric battery (for over 3500 h at 1 mA cm-2), and remarkable cycle stability in Na metal full batteries. This work offers a novel strategy to design a sodiophilic scaffold by nanoclay for dendrite-free Na metal anodes.

Automated summary

Researchers achieved uniform sodium deposition by using halloysite nanotubes as insulated scaffolds and introducing Ag nanoparticles as sodiophilic sites. The presence of Ag greatly increased the binding energy of sodium on HNTs/Ag. The coordination between HNTs and Ag contributed to high Coulombic efficiency, long lifespan, and remarkable cycle stability in Na metal full batteries.