Lattice Distortion Regulates Na-Ion Percolation in High-Entropy Cation-Disordered Rocksalt Cathodes

Abstract

Ion percolation in cation-disordered rocksalt (DRX) Na-ion cathodes is conventionally viewed as a topological problem governed by the connectivity of zero-transition-metal (0-TM) channels. Here, we show that configurational-entropy-induced lattice distortion extends this paradigm by rendering nominally unfavorable 1-TM pathways kinetically accessible in high-entropy DRX cathodes. Guided by a mixing-temperature-based design strategy, we identify a synthetically accessible Na-rich high-entropy DRX cathode, Na1.2Ti0.133Mn0.133Nb0.133V0.133Fe0.133Mo0.133O2, with a percolation-limited accessible capacity of 260.0 mAh g–1 and a corresponding theoretical gravimetric energy density of 718.8 Wh kg–1. First-principles calculations and machine-learning-accelerated hybrid Monte Carlo–molecular dynamics simulations reveal two coupled effects governing Na+ transport: suppressed short-range order enhances 0-TM connectivity, while lattice distortion lowers migration barriers along 1-TM pathways, expanding the effective percolation network beyond the conventional 0-TM limit. These findings recast ion percolation as a topology–kinetics-coupled phenomenon and establish lattice adaptability as a design variable for engineering fast ion transport in high-entropy cathodes.