Reliable electrochemical investigations of electrode materials are indispensable for the development of next-generation energy storage devices. In the case of multivalent cation-based electrochemistry, intense attention should be paid to the cell configuration for obtaining reliable data. In particular, the electrolyte and reference electrode must be appropriately selected considering the potential window of electrolyte and the validity of reference. Here, we demonstrate the detailed electrochemical examination for the Mg²⁺-storage capability of the NASICON-type framework derived from Na₃V₂(PO₄)₃ (NVP). A combination of the Mg(BF₄)₂-based electrolyte with high anodic stability and the reliable Ag pseudo-reference electrode offers decent electrochemical test results. Despite suffering from the polarization concerning magnesiation, the desodiated NVP electrode can deliver a well-defined discharge plateau at ∼2.7 V (vs Mg²⁺/Mg) with the reversible capacity of >100 mAh g^–1 at room temperature. The impedance analysis results indicate that the increased charge transfer resistance on discharging due to the high energy barrier for desolvation of divalent cations is responsible for the large polarization but not extremely significant, allowing for the room-temperature operation. The findings obtained herein also highlight the importance of the structural robustness of host lattice, which is required to withstand the strong amorphization during Na⁺ extraction and Mg²⁺ insertion/extraction.

中文翻译：

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镁离子在Mg（BF ₄）_2基电解质中的坚固NASICON型晶体晶格中镁离子的可逆电化学插入/抽出

电极材料的可靠电化学研究对于下一代储能设备的开发是必不可少的。在基于多价阳离子的电化学的情况下，应格外注意电池配置以获得可靠的数据。特别地，必须考虑电解质的电势窗口和参考的有效性来适当地选择电解质和参比电极。在这里，我们展示了对Na ₃ V ₂（PO ₄）₃（NVP）衍生的NASICON型骨架的Mg ²⁺储存能力的详细电化学检查。Mg（BF ₄）_2的组合阳极稳定性高的银基电解质和可靠的银伪参比电极可提供不错的电化学测试结果。尽管遭受放大极化的困扰，但经过去污的NVP电极仍可在〜2.7 V（vs Mg ²⁺ / Mg）处提供清晰的放电平台，可逆容量> 100 mAh g ^–1在室温下。阻抗分析结果表明，由于用于二价阳离子去溶剂化的高能垒，放电时电荷转移电阻的增加是造成大极化的原因，但并不是非常明显，这允许在室温下运行。本文获得的发现还突出了主体晶格结构坚固性的重要性，这是承受Na ⁺萃取和Mg ²⁺插入/萃取过程中强烈非晶化所必需的。