Atomic-Level Intercalation Strategy Enabling Ultrastable Subnanochannels for Long-Lifespan Zn-Ion Batteries

Two-dimensional materials are widely used to construct interface protective coatings (IPCs) to suppress dendritic growth by facilitating uniform Zn²⁺ flux through their ordered ion transport channels. However, during the plating/stripping cycles, IPCs are subjected to solvent-induced swelling effects, leading to the rupture of IPCs and hindering the ordered deposition of zinc ions. Here, using MXene as a model, an atomic-level intercalation strategy was developed to construct an IPC with antiswelling properties and stable subnanometer channels. Metal ions are inserted into the MXene layers, effectively locking the layered structure through strong coordination interactions and electrostatic attraction. The atomic-level metal ions occupy minimal space, maximizing the utilization of MXene's interlayer channels. Among all of the screened metal ion-intercalated MXene membranes (M-MXMs), Al³⁺-MXM exhibits the best stable performance with only 0.5% static expansivity. The Al³⁺-MXM@Zn symmetric battery achieves a high Zn ion migration number of 0.75 and exhibits stable cycling at 2800 h under 1 mA cm^-2, 1 mAh cm^-2. The Al³⁺-MXM@Zn-I₂ battery reserved a capacity retention rate of 83.5% after 10,000 cycles at 2 A g^-1.