<br>钙掺杂Na3V2(PO4)2F3/C钠离子电池正极材料的电化学性能增强,ACS Applied Materials & Interfaces

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钙掺杂Na3V2(PO4)2F3/C钠离子电池正极材料的电化学性能增强
ACS Applied Materials & Interfaces ( IF 8.2 ) Pub Date : 2023-12-19 , DOI: 10.1021/acsami.3c12772
Diah Agustina Puspitasari, Jagabandhu Patra, Rahmandhika Firdauzha Hary Hernandha, Yu-Shen Chiang, Atsushi Inoishi, Bor Kae Chang, Tai-Chou Lee, Jeng-Kuei Chang

具有NASICON结构的Na ₃ V ₂ (PO ₄ ) ₂ F ₃ (NVPF)由于其稳定的3D结构、快速的离子扩散通道、高工作电压和令人印象深刻的循环稳定性而作为正极材料而受到关注。然而，材料的低本征电子电导率导致其倍率性能较差，这对实际应用提出了重大挑战。在此，我们使用简单的溶胶-凝胶和碳热还原方法开发了一系列具有不同Ca ²⁺掺杂水平的Ca掺杂NVPF/C阴极材料。 X射线衍射分析证实Ca ²⁺的加入不会改变母材的晶体结构，而是扩大了晶格间距。密度泛函理论计算表明，在V ³⁺位点取代Ca ²⁺离子会减小带隙，从而导致电子电导率增加。这种取代还增强了结构稳定性，防止充电/放电循环期间的晶格畸变。此外，Ca ²⁺离子的存在在带隙内引入了两种局域态，从而与掺镁的NVPF/C相比增强了电化学性能。最佳的 NVPF-Ca-0.05/C 正极在 0.1 C 和 10 C 下分别表现出 124 和 86 mAh g ^–1的优异比容量。此外，NVPF-Ca-0.05/C 在 10 C 下进行 1000 次充电/放电循环后，容量保持率为 70%。这些显着的结果可归因于优化的粒径、优异的结构稳定性以及增强的离子和电子电导率通过Ca掺杂。我们的研究结果为开发具有理想电化学性能的阴极材料提供了宝贵的见解。

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Enhanced Electrochemical Performance of Ca-Doped Na3V2(PO4)2F3/C Cathode Materials for Sodium-Ion Batteries

Na₃V₂(PO₄)₂F₃ (NVPF) with a NASICON structure has garnered attention as a cathode material owing to its stable 3D structure, rapid ion diffusion channels, high operating voltage, and impressive cycling stability. Nevertheless, the low intrinsic electronic conductivity of the material leading to a poor rate capability presents a significant challenge for practical application. Herein, we develop a series of Ca-doped NVPF/C cathode materials with various Ca²⁺ doping levels using a simple sol–gel and carbon thermal reduction approach. X-ray diffraction analysis confirmed that the inclusion of Ca²⁺ does not alter the crystal structure of the parent material but instead expands the lattice spacing. Density functional theory calculations depict that substituting Ca²⁺ ions at the V³⁺ site reduces the band gap, leading to increased electronic conductivity. This substitution also enhanced the structural stability, preventing lattice distortion during the charge/discharge cycles. Furthermore, the presence of the Ca²⁺ ion introduces two localized states within the band gap, resulting in enhanced electrochemical performance compared to that of Mg-doped NVPF/C. The optimal NVPF-Ca-0.05/C cathode exhibits superior specific capacities of 124 and 86 mAh g^–1 at 0.1 and 10 C, respectively. Additionally, the NVPF-Ca-0.05/C demonstrates satisfactory capacity retention of 70% after 1000 charge/discharge cycles at 10 C. These remarkable results can be attributed to the optimized particle size, excellent structural stability, and enhanced ionic and electronic conductivity induced by the Ca doping. Our findings provide valuable insight into the development of cathode material with desirable electrochemical properties.

更新日期：2023-12-19

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