Layered Structure Modification of Sodium Vanadate through Ca/F Co-Doping for Enhanced Energy Storage Performance,Advanced Energy Materials

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Layered Structure Modification of Sodium Vanadate through Ca/F Co-Doping for Enhanced Energy Storage Performance
Advanced Energy Materials ( IF 24.4 ) Pub Date : 2024-09-09 , DOI: 10.1002/aenm.202401481
Jiajia Han _{1,

2} , Shuting Gao _{1,

2} , Zhefei Sun _{1,

2} , Zonghua Yang _{1,

2} , Xingjun Liu _{1,

3,

4} , Cuiping Wang _{1,

2}

Affiliation

Vanadate materials are promising for sodium-ion batteries (SIBs) due to their low cost, high capacity, and high power characteristics enabled by vanadium's multiple oxidation states. However, their development is hindered by poor conductivity, suboptimal high-rate performance, and limited cycle life. In this work, a layered structure modification strategy involving Ca/F co-doping in sodium vanadate Na₂CaV₂O₆F (CVF) is proposed to address these issues. Through a combination of experiments and density functional theory calculations, it is demonstrated that Ca/F synergies enhance the Na layer spacing in CVF, resulting in reduced crystal water content and volume shrinkage compared to Na₂V₂O₆ (NVO). Additionally, Ca/F incorporation significantly mitigates the diffusion potential of Na⁺ within the material framework. The unmodified CVF sample exhibits a high reversible capacity of 220 mAh g⁻¹ at 10 mA g⁻¹ and an excellent rate capacity of 65.78 mAh g⁻¹ at 400 mA g⁻¹. Furthermore, the cathode material maintains a capacity of up to 138 mAh g⁻¹ at 200 mA g⁻¹ and retains 104.88 mAh g⁻¹ after 100 cycles within the voltage range of 1.5−4.0 V. These findings enhance the understanding of the crystal structure of NVO cathode materials and pave the way for the rational design of high-quality vanadate cathodes for SIBs.

中文翻译：

通过 Ca/F 共掺杂对钒酸钠进行层状结构改性以增强储能性能

钒酸盐材料因其低成本、高容量和高功率特性而有望用于钠离子电池（SIB），因为钒的多种氧化态使其具有高功率特性。然而，它们的开发受到导电性差、次优的高倍率性能和有限的循环寿命的阻碍。在这项工作中，提出了一种涉及钒酸钠 Na₂CaV₂O₆F （CVF）中 Ca/F 共掺杂的分层结构修饰策略来解决这些问题。通过实验和密度泛函理论计算的结合，证明 Ca/F 协同作用增强了 CVF 中的 Na 层间距，与 Na₂V₂O₆ （NVO）相比，结晶水含量和体积收缩率降低。此外，Ca/F 掺入显著降低了 Na⁺ 在材料框架内的扩散潜力。未修饰的 CVF 样品在 10 mA ^g-1 时表现出 220 mAh ^g-1 的高可逆容量，在 400 mA ^g-1 时表现出 65.78 mAh ^g-1 的出色倍率容量。此外，正极材料在 200 mA ^g-1 时保持高达 138 mAh ^g-1 的容量，并在 1.5-4.0 V 的电压范围内循环 100 次后保持 104.88 mAh ^g-1。这些发现增强了对 NVO 正极材料晶体结构的理解，并为合理设计用于 SIB 的高质量钒酸盐正极铺平了道路。

更新日期：2024-09-09

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