The dendrite growth in 3D structured lithium metal anodes: Electron or ion transfer limitation?

Lithium metal is among the most promising anode materials in next-generation energy-storage systems. However, the practical applications of lithium metal batteries have been severely hindered by the uncontrollable growth of lithium dendrites. If the mechanisms behind the lithium dendrite growth behavior are well understood and the critical condition to determine the rate limitation in electroplating and stripping process are clarified, it is feasible to boost the stable cycling of composite anode through the rational design of 3D structured lithium metal anodes. Herein we employed phase field model to quantitatively describe the lithium dendrite growth in various conductive structured lithium anodes. We found that the structural areal surface area linearly determines the electroplating reaction rate in the forepart kinetic process, which is limited by electron transfer in the composite Li metal anode. Meanwhile, the structural pore-volumetric surface area exhibits an inversely proportional relationship on the electroplating reaction rate in later kinetic process, which is limited by ion transfer in electrolyte. Structured lithium metal anodes with larger areal surface area and smaller pore-volumetric surface area can be much better for high rate and high capacity battery cycling.