Colloidal Synthesis of Na 2 Fe 2 (SO 4 ) 3 Nanocrystals as the Cathode Toward High‐Rate Capability and High‐Energy Density Sodium‐ion Batteries

作者：Yanze Li, Weihuang Wang, Yixin Jia, Huidong Xu, Rui Liu, Zheng Wang, Zicheng Xie, Lantian Zhang, Rong He, Liangbing Wang · 发表于：Small Methods · 年份：2025 · DOI：10.1002/smtd.202402110 · 被引用次数：10 · 研究领域：Advancements in Battery Materials、Advanced Battery Materials and Technologies、Extraction and Separation Processes

Abstract Alluaudite‐type Na 2+2x Fe 2‐x (SO 4 ) 3 (NFS) with high theoretical energy density is regarded as the promising cathode of sodium‐ion batteries (SIBs), while practical rate and cyclic performances are still hindered by intrinsic poor conductivity. Here, a facile method is developed, collaborating high‐boiling organic solvents assisted colloidal synthesis (HOS‐CS) with sintering for tailoring Na 2 Fe 2 (SO 4 ) 3 nanocrystals decorated by conductive carbon network toward high‐rate‐capability cathode of SIBs. Impressively, the as‐prepared Na 2 Fe 2 (SO 4 ) 3 @MC provides 60.6 and 46.9 mAh g −1 of reversible capacities even at ultrahigh rates of 20 and 30 C, respectively, ranking the superior state among the current NFS‐based cathode. More importantly, Na 2 Fe 2 (SO 4 ) 3 @MC achieves 73% of capacity retention at 20 C after 500 cycles, highlighting its potential for application as a fast chargeable cathode. As a bonus, the full‐cell configuration constructed with Na 2 Fe 2 (SO 4 ) 3 @MC cathode and commercial hard carbon (HC) anode delivers 45.6 mAh g −1 at 10 C and 68.3 mAh g −1 of initial capacity with ≈79.4% of retention after 100 cycles at 2 C. Also, Na 2 Fe 2 (SO 4 ) 3 @MC||HC full cell supplies as high as 140 Wh kg −1 of practical energy density. This work offers a novel approach to prepare NFS cathode for SIBs with both high energy density and fast‐charging ability.