The accessibility of high‐performance sodium‐ion batteries (SIBs) hinges upon cathodes with high voltage and large reversible capacity. Among the contenders, vanadium‐based polyanionic compound with strong inductive effect from anionic group and multiple accessible oxidation states of vanadium emerged as a formidable competitor, however, only limited candidates in this field were reported so far. This manuscript delineated the rational synthesis of a novel off‐stoichiometric pyrophosphate Na6.51V3.16(P2O7)4. It delivers a specific capacity of 102 mAh g‐1 at the current density of 20 mA g‐1, as well as a high discharge median voltage of 3.87 V vs. Na+/Na, rendering it a rare sodium‐ion storage host with multi‐redox couples (V5+/4+/3+/2+). The experimental approach to phase adjustment in this article offers guidelines for exploiting of new cathode materials for high‐performance SIBs.

中文翻译：

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用于可充电钠离子电池的高压非化学计量钒基焦磷酸盐 Na6.51V3.16(P2O7)4

高性能钠离子电池（SIB）的可用性取决于高电压和大可逆容量的正极。在这些竞争者中，具有强大的阴离子基团诱导效应和钒的多种易氧化态的钒基聚阴离子化合物成为了强大的竞争者，但迄今为止，该领域的候选者报道有限。该手稿描述了新型非化学计量焦磷酸盐 Na6.51V3.16(P2O7)4 的合理合成。它在 20 mA g-1 的电流密度下提供 102 mAh g-1 的比容量，以及 3.87 V vs. Na+/Na 的高放电中值电压，使其成为一种罕见的具有多种特性的钠离子存储主体。 ‐氧化还原对（V5+/4+/3+/2+）。本文中的相位调整实验方法为开发高性能 SIB 的新型阴极材料提供了指导。