Wang Yu-Jie, Gu Zhen-Yi, Bai Dong-Sheng, Hao Ze-Lin, Huang Han-Wei, Yan Yang, Li Cheng-Jie, Liu An-Min, Wu Xing-Long
School of Chemical Engineering, ocean and life science, Dalian University of Technology, Panjin, Liaoning, 124221, P.R. China.
State Key Laboratory of Integrated Optoelectronics, MOE Key Laboratory for UV Light-Emitting Materials and Technology, Northeast Normal University, Changchun, Jilin, 130024, P.R. China.
Angew Chem Int Ed Engl. 2025 Aug 4;64(32):e202507573. doi: 10.1002/anie.202507573. Epub 2025 Jun 8.
The NaFe(PO)(PO) (NFPP) cathode material faces the challenge of coordinating the improvement of high-rate performance and long-cycle stability for sodium-ion batteries (SIBs). This study proposes an ionic polarization-driven defect engineering strategy, which regulates the electronic structure and Na transmission dynamics of NFPP through Bi doping. Experimental results and theoretical calculations show that Bi with (18 + 2) electron configuration significantly enhances the crystal structure stability of NFPP by strengthening the covalency of Bi─O bonds. Meanwhile, the heterovalent Bi doping optimizes the bandgap of the material (from 3.29 to 0.16 eV) and promotes Na diffusion, while introducing lattice defects to provide additional sodium storage sites. The optimized 0.02Bi-NFPP cathode exhibits excellent electrochemical performance as the half-cell only takes 31.6 min to charge to 80% at a rate of 1 C, and the capacity decay is only 0.000495 mA h g per cycle (86.9% capacity retention) over 20,000 cycles at 20 C. The full battery based on hard carbon anode maintains 95.5% capacity retention after 200 cycles at 1 C. This study reveals the synergistic mechanism between ion polarization effect and lattice defects, and provides a new strategy for designing SIBs cathode materials with both fast charging/discharging capabilities and ultra-long life.
NaFe(PO)(PO)（NFPP）正极材料面临着协调钠离子电池（SIBs）高倍率性能提升和长循环稳定性的挑战。本研究提出了一种离子极化驱动的缺陷工程策略，通过Bi掺杂来调节NFPP的电子结构和Na传输动力学。实验结果和理论计算表明，具有（18 + 2）电子构型的Bi通过增强Bi─O键的共价性显著提高了NFPP的晶体结构稳定性。同时，异价Bi掺杂优化了材料的带隙（从3.29 eV降至0.16 eV）并促进了Na扩散，同时引入晶格缺陷以提供额外的钠存储位点。优化后的0.02Bi-NFPP正极表现出优异的电化学性能，半电池在1 C倍率下仅需31.6分钟即可充电至80%，在20 C下20000次循环中容量衰减仅为0.000495 mA h g每循环（容量保持率86.9%）。基于硬碳负极的全电池在1 C下200次循环后容量保持率为95.5%。本研究揭示了离子极化效应与晶格缺陷之间的协同机制，并为设计兼具快速充放电能力和超长寿命的SIBs正极材料提供了新策略。
