Constructing nanolaminate structures with covalent bridges for high-performance photo-assisted Zn-ion storage

Photo-assisted rechargeable zinc-ion batteries (PAZIBs) have received extensive attention due to their promising performance under illumination. However, the development of highly efficient photocathodes for PAZIBs, with high capacity and durability, remains a significant challenge. Herein, we construct a nanolaminate MnO 2 /polypyrrole stack (PPy-MnO 2 ) through an in situ polymerization technique, which is used to boost the overall performance of PAZIBs. Through density-functional theory (DFT) calculations, we verify that the intercalation of the PPy polymer chains within δ -MnO 2 interlayers can help in expanding the interlayer spacing and facilitating the Zn 2+ insertion. Furthermore, we discover that the in situ polymerization pathway induces oxygen vacancies in the δ -MnO 2 layers, which enables the direct bonding between the bare Mn and N from pyrrolic rings, resulting in twisted polymer steric structures in the nanolaminates. This further expands the interlayer spacing, provides additional Zn 2+ interactions, generating additional electron pathways, and optimizes the bandgap structures. Therefore, PAZIBs with PPy-MnO 2 nanolaminates display high specific capacities (523 mAh g −1 under illumination vs. 318 mAh g −1 under dark conditions) and excellent cycling behavior (95.7% after 1500 cycles). This work opens up new avenues for designing efficient and environmentally friendly photoelectrode materials for advanced energy storage applications.