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Bulk-Interface Synergy Enables Stable High-Voltage P2-Type Layered Oxide Cathodes for Fast-Charging Sodium-Ion
Pengyuan Wang1,2,3, Yangjie Liu1, Ziting Chen1,2,3
1State Key Laboratory of Structural Chemistry, and Fujian Provincial Key Laboratory of Materials and Techniques toward Hydrogen Energy, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China.
Abstract:
P2-type layered oxides hold great promise for high-energy sodium-ion batteries (SIBs) but are hindered by irreversible P2-O2 transitions and interfacial degradation that accelerate capacity fading. Herein, we present a bulk-interface dual-engineering strategy through synergistic Mg2+ doping and CeO2 surface modulation to overcome these challenges. The designed P2-type Na0.67Mg0.1Ni0.23Mn0.67O2-CeO2 (NNMMO-Ce) cathode integrates structural reinforcement and redox synergy: bulk Mg2+ stabilizes the lattice, widens Na+ diffusion channels, and suppresses destructive high-voltage transitions, while a conformal CeO2 nanolayer buffers lattice strain (∼0.9%), prevents intragranular cracking, and enables the storage and release of (O2)n- species through reversible Ce3+/Ce4+ redox activity. This coupled mechanism coordinates electron-ion transport, minimizes polarization effects, and significantly reduces charge transfer resistance as well as the escape of lattice oxygen. Consequently, NNMMO-Ce exhibits superior performance with 94.0% capacity retention at 0.1 C and 66.2 mAh g-1 at 20 C, along with highly reversible P2-OP4 transitions and >35-fold enhanced Na+ diffusion. When paired with a hard-carbon anode, the full cell delivers a high energy density of 258.97 Wh kg-1 and excellent cycling stability over 2-4.35 V. This work establishes a cooperative bulk-interface strategy for constructing high-capacity, fast-charging, and long-lived SIB cathodes.
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