A Tellurium-Boosted High-Areal-Capacity Zinc-Sulfur Battery.

ABSTRACT

Aqueous rechargeable zinc-sulfur (Zn-S) batteries are a promising, cost-effective, and high-capacity energy storage technology. Still, they are challenged by the poor reversibility of S cathodes, sluggish redox kinetics, low S utilization, and unsatisfactory areal capacity. This work develops a facile strategy to achieve an appealing high-areal-capacity (above 5 mAh cm-2) Zn-S battery by molecular-level regulation between S and high-electrical-conductivity tellurium (Te). The incorporation of Te as a dopant allows for manipulation of the Zn-S electrochemistry, resulting in accelerated redox conversion, and enhanced S utilization. Meanwhile, accompanied by the S-ZnS conversion, Te is converted to zinc telluride during the discharge process, as revealed by ex-situ characterizations. This additional redox reaction contributes to the S cathode's total excellent discharge capacity. With this unique cathode structure design, the carbon-confined TeS cathode (denoted as Te1S7/C) delivers a high reversible capacity of 1335.0 mAh g-1 at 0.1 A g-1 with a mass loading of 4.22 mg cm-2, corresponding to a remarkable areal capacity of 5.64 mAh cm-2. Notably, a hybrid electrolyte design uplifts discharge plateau, reduces overpotential, suppresses Zn dendrites growth, and extends the calendar life of Zn-Te1S7 batteries. This study provides a rational S cathode structure to realize high-capacity Zn-S batteries for practical applications.