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Material Sciences 2025
硼化铌掺杂石榴石固态电解质的制备工艺优化与电化学性能研究
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Abstract:
本研究旨在通过引入不同浓度的NbB2掺杂，探索其对LLZTO(Li6.75La3Zr1.75Ta0.25O12)固态电解质性能的影响。研究表明，适量的NbB2掺杂能够显著改善LLZTO的微观结构和电化学性能。通过球磨法将NbB2引入LLZTO中，结果表明，1%掺杂浓度的NbB2在1150℃下烧结2小时的样品表现出最佳的电化学性能，室温下的离子电导率为8.16 × 10？4 S·cm？1，阻抗最低，仅为210 Ω。进一步的研究表明，掺杂NbB2有助于优化LLZTO的离子迁移路径，增强界面稳定性，并改善晶界的融合，降低烧结过程中的失败率。X射线衍射(XRD)和扫描电子显微镜(SEM)分析显示，掺杂的NbB2均匀分布于LLZTO的晶格和晶界中，未引起主晶相的显著变化，且材料的晶相结构保持稳定。XPS分析主要揭示了掺杂5% NbB2后，LLZTO样品中Nb和B元素的化学状态及其与材料性能之间的潜在关系，混合价态有助于提升离子导电性增强和改善界面稳定性。电化学测试表明，掺杂NbB2的LLZTO陶瓷样品在长循环过程中展现出优异的稳定性，特别是1%掺杂浓度的样品，其极化电压较低，库仑效率接近100%，显著提高了电池的循环寿命。
This study aims to explore the effects of NbB2 doping at varying concentrations on the performance of LLZTO (Li6.75La3Zr1.75Ta0.25O12) solid-state electrolytes. The results demonstrate that appropriate NbB2 doping significantly improves the microstructure and electrochemical properties of LLZTO. Through the ball milling method, NbB2 was incorporated into LLZTO, and the sample with 1% NbB2 doping sintered at 1150？C for 2 hours exhibited optimal electrochemical performance, achieving a room-temperature ionic conductivity of 8.16 × 10？4 S·cm？1 and the lowest impedance of 210 Ω. Further analysis revealed that NbB2 doping optimizes lithium-ion migration pathways, enhances interfacial stability, improves grain boundary fusion, and reduces failure rates during sintering. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses confirmed the uniform distribution of NbB2 within the LLZTO lattice and grain boundaries, with no significant alteration to the main crystalline phase and maintained structural stability. XPS analysis mainly reveals the chemical states of Nb and B elements in LLZTO samples doped with 5% NbB2 and their potential relationship with material properties. The mixed valence state helps to enhance ion conductivity and improve interface stability. Electrochemical tests indicated that NbB2-doped LLZTO ceramic samples exhibit excellent cycling stability,
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