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.