A Multielectron-Reaction and Low-Strain Na3.5Fe0.5VCr0.5(PO4)3 Cathode for Na-Ion Batteries,ACS Energy Letters

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A Multielectron-Reaction and Low-Strain Na3.5Fe0.5VCr0.5(PO4)3 Cathode for Na-Ion Batteries
ACS Energy Letters ( IF 19.3 ) Pub Date : 2023-08-04 , DOI: 10.1021/acsenergylett.3c01183
Han Li ₁ , Yao Wang ₁ , Xudong Zhao ₂ , Junteng Jin ₁ , Qiuyu Shen ₁ , Jie Li ₁ , Yukun Liu ₁ , Xuanhui Qu ₁ , Lifang Jiao ₃ , Yongchang Liu _{1,

3}

Affiliation

Natrium superionic conductor (NASICON)-type phosphates have attracted widespread attention as cathodes for sodium-ion batteries (SIBs) due to their 3D open frameworks facilitating Na⁺ diffusion, but they are characterized by mediocre energy density or rapid capacity decay. Herein, we delicately design a multielectron-reaction and low-strain Na_3.5Fe_0.5VCr_0.5(PO₄)₃/C cathode material featuring a high working voltage (∼3.43 V), high reversible capacity (148.5 mAh g^–1), and high cycling stability (95.1% capacity retention over 2000 cycles). The deviation in the reaction potential of each redox couple (Fe²⁺/Fe³⁺, V³⁺/V⁴⁺/V⁵⁺, and Cr³⁺/Cr⁴⁺) efficaciously alleviates the lattice strain accumulation, ensuring a small cell volume variation of 3.87% during the highly reversible charge–discharge processes, as confirmed by systematic in situ/ex situ analyses. Moreover, the fast reaction kinetics and the unexpected reversible Na1-ion (6b site) release/uptake are elucidated via multiple electrochemical characterizations and theoretical computations. This rational design strategy of incorporating versatile redox couples with different roles will broaden the horizons of high-performance NASICON-type cathodes.

中文翻译：

钠离子电池多电子反应低应变Na3.5Fe0.5VCr0.5(PO4)3阴极

钠超离子导体（NASICON）型磷酸盐由于其3D开放框架有利于Na ⁺扩散，作为钠离子电池（SIB）的阴极而受到广泛关注，但其特点是能量密度平庸或容量衰减快。在此，我们精心设计了一种多电子反应低应变Na _3.5 Fe _0.5 VCr _0.5 (PO ₄ ) ₃ /C正极材料，具有高工作电压（∼3.43 V）、高可逆容量（148.5 mAh g ^–1）、高循环稳定性（2000 次循环后容量保持率为 95.1%）。各氧化还原对（Fe ²⁺ /Fe ³⁺、V ³⁺ /V ⁴⁺ /V ⁵⁺和 Cr ³⁺ /Cr ⁴⁺）有效减轻晶格应变积累，确保在高度可逆的充放电过程中电池体积变化小至 3.87%，如下所示：系统的原位/异位分析。此外，通过多种电化学表征和理论计算阐明了快速反应动力学和意想不到的可逆Na1离子（6b位点）释放/吸收。这种结合具有不同作用的多功能氧化还原对的合理设计策略将拓宽高性能 NASICON 型阴极的视野。

更新日期：2023-08-04

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