Dual-Stabilized Three-Dimensional Honeycomb-Like MXene/Prussian Blue Analogue Composites for High-Performance Aqueous Sodium-Ion Batteries

Aqueous sodium-ion batteries (ASIBs) are critically challenged by insufficient cycle life and low capacity, predominantly originating from the structural instability of electrode materials. Herein, a stable three-dimensional (3D) honeycomb-like MXene (HMX) framework is designed as a host material for sodium cobalt hexacyanoferrate (NaCoHCF) to function as a high-performance cathode in ASIBs, enabling efficient sodium-ion storage through its interconnected conductive architecture. The HMX host serves as a conductive stress-buffering matrix that simultaneously suppresses crystal structure distortion in NaCoHCF, prevents nanoparticle coalescence, and creates an electron transport network. Crucially, the honeycomb configuration not only eliminates MXene restacking but also exposes abundant ion-accessible active sites through its tortuous multidirectional channels. With these synergistic advantages of the composite structure, the NaCoHCF/HMX-based half-cell achieves a high discharge specific capacity of 123.7 mAh g^-1 at 0.1 A g^-1. Significantly, it maintains 82.4% of its initial capacity after 10,000 cycles at 2.0 A g^-1. Moreover, the assembled full-cell, NaCoHCF/HMX∥NaTi₂(PO₄)₃@C, exhibits remarkable cycling stability with 94.4% capacity retention after 2500 cycles, maintaining a high reversible capacity of 107.5 mAh g^-1 at 1.0 A g^-1. Density functional theory (DFT) calculations verify the interfacial coupling and synthesis mechanism of NaCoHCF/HMX. This work offers a feasible strategy for advancing PBAs-based materials in ASIBs applications.