Vanadium flow battery (VFB) promises a route for achieving grid‐scale power storage by harnessing renewable energy sources. However, the sluggish reaction kinetics of vanadium redox couples and serious hydrogen evolution reaction (HER) still restrict the further development of VFB. Addressing these challenges requires not only effective solutions but also ones that are cost‐efficient and scalable to meet the demands of affordable energy storage. Here, we present an in‐situ constructed Cu@Cu6Sn5 core‐shell catalyst by incorporating metal ions into the electrolyte. The Cu core, encapsulated by the Cu6Sn5 shell, forms an excellent conductive pathway to the graphite felt electrode. Charge transfer between Cu and Sn within Cu6Sn5 shell accelerates the reaction kinetics of V2+/V3+ redox couple and selectively inhibits HER, as confirmed through in‐situ weak measurement imaging method. The Cu@Cu6Sn5 battery achieves a peak power density of 1119.1 mW cm‐2 at 1350 mA cm‐2, operates stably for 1200 cycles without catalyst failure, and is available over a wide‐temperature range. Furthermore, we identify a demand of subzero capacity unlocking. Achieving a 23.4% theoretical capacity unlocking at ‐10 °C with a cut‐off voltage up to 1.75 V, bespeaking a crucial breakthrough toward cost‐effective VFB.

中文翻译：

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原位构建的核壳催化剂可实现经济高效且长寿命的钒液流电池的零下容量解锁


钒液流电池 （VFB） 有望通过利用可再生能源实现电网规模的电力存储。然而，钒氧化还原对反应动力学缓慢和严重的析氢反应 （HER） 仍然限制了 VFB 的进一步发展。应对这些挑战不仅需要有效的解决方案，还需要具有成本效益和可扩展性的解决方案，以满足经济实惠的储能需求。在这里，我们提出了一种通过将金属离子掺入电解质Cu@Cu6Sn5原位构建的核壳催化剂。由 Cu6Sn5 壳封装的 Cu 核心形成了通往石墨毡电极的极好导电通路。Cu6Sn5 壳内 Cu 和 Sn 之间的电荷转移加速了 V2+/V3+ 氧化还原对的反应动力学，并选择性地抑制了 HER，这通过原位弱测量成像方法证实了这一点。Cu@Cu6Sn5 电池在 1350 mA cm-2 时可实现 1119.1 mW cm-2 的峰值功率密度，可稳定运行 1200 次循环而不会发生催化剂故障，并在较宽的温度范围内可用。此外，我们确定了对零度以下容量解锁的需求。在 -10 °C 时实现 23.4% 的理论容量解锁，截止电压高达 1.75 V，这是实现经济高效的 VFB 的重要突破。