Synergistic Effects of Cu(OH) 2 ‐CuO Anodes for Multiple‐Step Energy Storage of Li‐Ion Microbatteries

Abstract Lithium‐ion microbatteries (LIMBs) face challenges in achieving high power density without compromising energy density, due to limitations in assembly and kinetics. By overcoming LIMB electrode fabricated using a laser‐assisted method, which significantly improves assembly precision and enhances reaction kinetics, the first anodization of Cu(OH) 2 ‐CuO nanoneedle hybrids on Cu foil for a LIB anode is reported. By resolving the limitations of previous metal‐hydroxide electrodes associated with conventional conversion reactions, the novel anode achieves an unprecedently‐high initial capacity of 3065 mAh g −1 which clearly exceeds the theoretical limit. X‐ray Photoelectron Spectroscopy, Transmission Electron Microscopy, and in‐situ Raman analysis revealed the nanoscale Cu‐particles and LiOH in high‐voltage reactions, alongside Cu x H y , Li 2 O, and LiH in low‐voltage hydride reactions. AIMD simulations additionally revealed the underlying atomistic mechanism. An in‐plane LIMB using a laser‐assisted method is further engineered, featuring in prelithiated Cu(OH) 2 ‐CuO as the anode and LiNi 0.8 Mn 0.1 Co 0.1 O 2 as the cathode. This LIMB operates between 2.0 and 4.5 V, delivering a reversible capacity of 6.61 mAh cm −2 at 20 µA cm −2 and retaining over 83% capacity after 500 cycles. This work advances overall understanding of lithium storage and offers key insights for the design of next‐generation LIMBs.