Dendrite-Free Lithium Metal Battery Enabled by Dendritic Mesoporous Silica Coated Separator

Concentration polarization-induced lithium dendrites seriously impede the practical application of high-energy-density lithium metal batteries. Porous materials that aim to inhibit lithium dendrites are extensively explored. However, their effects are still limited by the intrinsic features of the pores, especially channel geometry and surface properties. Herein, a separator modification strategy of blocking dendritic deposition via dendritic channels is proposed. A porous shield-like film is formed on the polypropylene separator through the close packing of ultra-small (approximate to 100 nm) silica nanospheres with unique dendritic mesopores (DMS). Besides the hierarchical pores homogenizing the ion flux, the DMS film also provides abundant Si(OH)(x) groups, preferentially adsorbing the TFSI- in the electrolyte and accelerating the transport of Li+. Most notably, the dendritic mesochannels with high complexity can diversify the growth directions of lithium and contribute to a more substantial homogenizing process of Li+. Consequently, a dendrite-free deposition with 1000 stable cycles in Li|Li symmetric cells even at 10 mA cm(-2) is achieved. This study provides a scalable approach for the fabrication of mesoporous separators and offers a fresh perspective on the future design of advanced separators utilized for dendrite suppression.

Automated summary

A modification strategy of separator is proposed to block dendritic deposition via dendritic channels and inhibit lithium dendrites in high-energy-density lithium metal batteries. A porous shield-like film is formed on the polypropylene separator using ultra-small silica nanospheres with unique dendritic mesopores. This film provides hierarchical pores for ion flux and abundant Si(OH)(x) groups for adsorbing TFSI- in the electrolyte and accelerating Li+ transport. The dendritic mesochannels diversify lithium growth directions and contribute to a more homogeneous deposition process, achieving dendrite-free deposition for stable cycles in Li|Li symmetric cells.