Towards anode-less lithium metal negative electrodes for secondary aprotic batteries

This study presents the synergistic application of optimized laser-induced periodic surface structure (LIPSS) patterning conducted under ambient conditions and the deposition of an artificial solid-state electrolyte (aSEI) for the fabrication of a novel lithium-less lithium metal electrode (L3ME) utilizing stainless steel (SS). The composite anode-less substrate demonstrates the capability to facilitate the reversible plating and stripping of metallic lithium over several hundred cycles in aprotic battery systems. The LIPSS technique generates a patterned surface characterized by micrometer-long ripples with a lateral periodicity ranging from 150 to 250 nm, whereas the deposition of the aSEI results in a uniform and smooth surface morphology achieved through the homogeneous dispersion of a polymeric-inorganic composite film. This research unveils, for the first time in the literature, the synergistic combination of laser patterning and aSEI pre-deposition, thereby advancing current methodologies for anode-less electrode fabrication. An extensive analysis was conducted on varying LIPSS patterning conditions and aSEI compositions to assess their implications on electrochemical performance. The constructed L3ME comprises a stainless steel thin foil featuring a mesostructured surface marked by a regular distribution of iron (Fe) and iron oxide (Fe2O3) ripples. This structured surface is seamlessly integrated beneath a uniform polyethylene oxide and lithium nitrate composite film, allowing for the manufacture, handling, and storage of L3ME substrates in dry air, eliminating the necessity for inert atmosphere conditions. The optimized L3ME electrodes exhibit remarkable performance in aprotic lithium cells, facilitating fully reversible metallic lithium stripping and deposition, with exceptionally high coulombic efficiencies nearing 100 % over numerous cycles across various galvanostatic conditions that adhere to commercial standards (current densities of 0.25–1.25 mA cm−2 and areal capacity limits from 0.5 to 5 mAh cm−2). Comparative benchmarking of L3ME performance against bare copper electrodes and other anode-less substrates highlights the distinctive efficacy of the combined LIPSS and aSEI technique in enhancing the reversibility of lithium plating and stripping through a selective inhibition of electrochemical lithium dissolution.