Nanostructured Sn Plating and Pre-Lithiation on Cu Current Collector for Anode-Free Lithium Batteries

Abstract

The fast and growing employment of Li-ion batteries in automotive and electrical mobility is pushing research towards the development of higher energy density and safer Li-ion batteries. Regarding the anodic material, metal and semi-metals as Al, Sn, Ag and Si are known to electrochemically alloy at low potential with lithium resulting in extremely high specific capacity, up to 4200 mAh/g for Li22Si5. However, severe issues as volumetric expansion and non-reversible lithium trapping strongly limit their cyclability and performances.[1] Anode-free Li battery (AFLB) strategy is a promising alternative to find a good compromise between safety and energy and power density because of the absence of an anodic active material in assembly phase. However, these systems suffer from severe challenges, including low coulombic efficiency (CE) due to intrinsic unstable interface that rapidly leads to dendritic growth and short-circuit.[2] To overcome this problem, nano-structuring of current collector has been demonstrated to be a valid approach to stabilize Li plating and stripping without dendrites formation.[3,4,5] In this work, we address current collector nano structuring by Sn plating as an efficient route for reversible Li plating/stripping. Interface stability is correlated with morphology of Sn deposits on Cu current collector in different conditions. Sn deposits were examined by AFM, SEM and XRD analysis and electrochemical behavior by galvanostatic charging and discharging cycles as well as EIS measurements. Sn pre-lithiation is also investigated as suitable strategy to further smoothing Li plating.