High‐Entropy‐Tailored d − p Orbital Hybridization in Na 3 V 2
Qifan Yang, Chen Cheng, Mengting Deng, Qianjie Niu, Simin Tang, Weidong Xu, Zheng Zhou, Lei Wang, Meiling Han, Yang Ling, Zengqing Zhuo, Liang ZhangABSTRACT
Polyanionic compounds are promising cathodes for sodium‐ion batteries (SIBs) owing to their robust structural frameworks and high operating voltage. However, their practical applications are hindered by poor intrinsic electronic conductivity alongside irreversible structural deterioration over deep desodiation. To overcome these issues, herein we report a high‐entropy Na 3 V 2 (PO 4 ) 2 O 2 F by incorporating multivalent cations (Cr 3+ , Mn 2+ , Fe 3+ , Co 2+ , Al 3+ ) into the V 4+ sites to rationally modulate V 3 d −O/F 2 p orbital hybridization. The comprehensive characterization results indicate that the high‐entropy modulation triggers an intricate charge redistribution that drives a dual strengthened d − p orbital hybridization: on the one hand, the strengthened σ‐type hybridization enhances the V−O covalency, endowing the framework with exceptional rigidity to mitigate volume variation; on the other hand, the concurrently enhanced π‐type hybridization via t 2g orbital modulation leads to improved intrinsic electronic conductivity. Because of these advantages, a synchronous surface‐to‐bulk vanadium redox reaction with highly reversible and durable dynamic evolution is achieved. Consequently, the designed Na 3 V 2 (PO 4 ) 2 O 2 F cathode delivers a high reversible capacity of 127.2 mAh g − 1 at 0.5 C with robust long‐term cycling stability. This study provides deep insights into developing high‐performance SIBs through localized orbital engineering by entropy modulation.