Air-stable lithium-sandwiched current collector for non-destructive, thermally safe, and sustained supplementary lithiation†

Contact prelithiation for anodes is a promising strategy to compensate for active lithium loss due to solid-state interface formation. However, existing research has predominantly focused on lithium thinning, neglecting issues of low lithium utilization and side reactions associated with lithium purification. Residues on the electrode surface can provoke additional side reactions, exacerbating cycling instability. Moreover, the thermal effects during contact prelithiation raise significant safety concerns for practical applications and remain understudied. To address surface issues, the lithium inventory was repositioned beneath the electrode using a lithiable current collector, sandwiching LiAg foil between two Cu foils (CLC). A 16 μm-thick CLC embedded with 5 μm LiAg was fabricated through a rolling process, while Cu foils underwent deformation, creating microholes during the thinning process. These microholes facilitate the sustained release of Li⁺ from CLC, thus mitigating Li plating without additional anode materials. The gradual release of Li⁺ also suppresses thermal runaway and electrode deformation, especially for Si anodes. Moreover, the CLC demonstrates excellent air stability, making it suitable as a current collector. The continuous electron pathway in CLC ensures a high lithium utilization of 97%. When integrated into LFP||Gr full cells, CLC enhances capacity retention from 80% to 96% after 400 cycles.