Nanocrystalline Li–Al–Mn-Si Foil as Reversible Li Host: Electronic Percolation and Electrochemical Cycling Stability

When a metallic foil (Li metal or LixAl) with initial Li inventory (LiInv) is used as the anode in lithium-ion batteries, its metallurgical damage state in the presence of organic liquid electrolyte and cycling electrochemical potential is of great interest. While LixAl foil operates at a voltage that eliminates LiBCC dendrite, the state-of-health (SOH) of LixAl anode can still degrade quickly in full-cell cycling. To analyze the causes, we decompose SOH = SOHe × SOHi × LiInv, where SOHe is SOH of electronic percolation within the anode, SOHi is SOH of Li percolation from cathode to the anode interior, and LiInv is the amount of cyclable lithium in a full cell, all normalized such that 1 means perfectly healthy, and 0 means dead. Any of the three (SOHe, SOHi, LiInv) dropping to zero would mean death of the full cell. Considering the poor performance of pure Al foil due to rapid drop in LiInv, we employed a mechanical prelithiation (MP) method to make LiInv >1 initially. The chemomechanical shock from MP c...