Spatially engineered Y2O3/rGO dual-modification empowers ultra-stable and high-rate Na3V2(PO4)3 cathodes
This work utilized Y 2 O 3 and rGO as additives, and systematically regulated their spatial distribution and composite ratio with Na 3 V 2 (PO 4 ) 3 (NVP) to overcome the bottlenecks faced by NVP, such as intrinsically low electronic conductivity, severe interfacial side reactions, and structural instability during cycling. The modified NVP cathode can significantly enhance its electrochemical performance, and improve its sodium storage and thermal safety performance in the pouch-type full cell. The as-prepared NVP@Y 2 O 3 @rGO material achieves an 84 % capacity retention rate after 1000 cycles at 1C&27 °C, while still delivering a specific capacity of 49.6 mAh g −1 at an ultra-high rate of 30C. Under elevated temperature of 45 °C, it maintains 91.5 % capacity retention after 400 cycles at 1C. In contrast, the pristine NVP retains only 38.2 %. Moreover, it exhibits a reversible capacity of 63.6 mAh g −1 even at an ultra-high rate of 40C. More importantly, pouch-type full cell testing further confirms its superior cycling stability (60.8 % capacity retention after 100 cycles, representing a 30.5 % improvement over the unmodified sample). Mechanistic studies reveal that the combined effects of Y 2 O 3 and rGO effectively facilitate electron/ion transport, suppress electrode-electrolyte interfacial side reactions, mitigate volume change stress, and enhance structural integrity. This work offers new insights for designing high-stability cathode materials for sodium-ion batteries.
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