Vacancy Modulating Co3Sn2S2 Topological Semimetal for Aqueous Zinc‐Ion Batteries

Weyl semimetals (WSMs) with high electrical conductivity and suitable carrier density near the Fermi level are enticing candidates for aqueous Zn‐ion batteries (AZIBs), meriting from topological surface states (TSSs). We propose a WSM Co3Sn2S2 cathode for AZIBs showing a discharge plateau around 1.5 V. By introducing Sn vacancies, extra redox peaks from the Sn4+/Sn2+ transition appear, which leads to more Zn2+ transfer channels and active sites promoting charge‐storage kinetics and Zn2+ storage capability. Co3Sn1.8S2 achieves a specific energy of 305 Wh kg−1 (0.2 Ag−1) and a specific power of 4900 Wkg−1 (5 Ag−1). Co3Sn1.8S2 and ZnxCo3Sn1.8S2 benefit from better conductivity at lower temperatures; the quasi‐solid Co3Sn1.8S2//Zn battery delivers 126 mAh g−1 (0.6 Ag−1) at −30 °C and a cycling stability over 3000 cycles (2 Ag−1) with 85 % capacity retention at −10 °C. A Weyl semimetal Co3Sn2S2 cathode was applied in aqueous Zn‐ion batteries with a discharge plateau around 1.5 V. Co3Sn1.8S2 activates Sn2+ and provides active sites with impressive charge‐storage capabilities and fast kinetic processes. The material has high structural stability and conductivity, and an ionic diffusion rate that achieves appreciable cycling stability and capacity retention.