Active‐Site‐Switching in Medium‐Entropy Metal Sulfides for Wide‐Temperature High‐Power Zn‐Air Pouch Cells

Abstract Quasi‐solid‐state Zn‐air pouch cells (QZPCs) promise a high energy‐to‐cost ratio while ensuring inherent safety. However, addressing the challenges associated with exploring superior energy‐wise cathode catalysts along with their activity origin, and the super‐ionic electrolytes remains a fundamental task. Herein, the realistic high‐performance QZPCs are contrived, underpinned by a robust NiVFeCo medium‐entropy metal sulfides (MESs) bifunctional air cathode with a record‐low potential polarization of 0.523 V, paired with a sodium polyacrylate‐ionic liquid hydrogel exhibiting exceptional conductivity (234 mS cm −1 ) and water retention (93.8% at 7 days) at room temperature as the super‐ionic conductor electrolyte. Through combined studies of in situ Raman, ex situ X‐ray absorption fine structure analysis, and theoretic calculations, an intriguing adaptive active‐sites‐switching mechanism of the MESs cathode during discharging/charging processes is unveiled, revealing a dynamic role transition of Co and Ni active sites in the reversible oxygen electrocatalysis. Consequently, the persistent low cathode polarization and super ion‐conductive electrolyte endorse QZPCs an excellent rate performance from 1 to 100 mA cm −2 at room temperature. Moreover, an impressively high cell‐level energy density of 105 Wh kg cell −1 with an ultra‐long cycle lifespan of 4000 cycles at 5 mA cm −2 and a low temperature of −30 °C is achieved.