The nucleation and growth mechanism of spherical Li for advanced Li metal anodes – a review

Metallic lithium (Li) is known as the "Holy Grail" of anode materials in the research area of Li-based batteries. However, Li metal anodes (LMAs) are plagued by infinite volume changes and dendrite formation during operation. Spherical Li exhibits rounded surfaces, which effectively mitigates the short circuit risks associated with dendritic Li, and has the smallest specific surface area compared to other deposit morphologies, thus enabling less electrolyte consumption and higher Coulombic efficiency (CE). What's more, three-dimensional (3D) conductive frameworks have good mechanical robustness and flexibility to withstand the volume changes that occur during cycling. This review systematically depicts the theoretical models for Li deposition, the mechanisms and formation conditions of spherical Li, and the benefits of the Li deposition model as well as the advantages of combining Li spheres with 3D conductive frameworks based on our previous works. We hope that this review can inspire researchers in this filed to pave the way for advanced LMAs.