Vacancy Modulating Co3Sn2S2 Topological Semimetal for Aqueous Zinc-Ion Batteries

摘要

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 Whkg(-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 mAhg(-1) (0.6 Ag-1) at -30 degrees C and a cycling stability over 3000 cycles (2 Ag-1) with 85% capacity retention at -10 degrees C.

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