Nayantara K. Wagh‡, Dong-Hyung Kim‡, Chi Ho Lee, Sung-Hae Kim, Han-Don Um, Joseph Sang-Il Kwon, Sambhaji S. Shinde, Sang Uck Lee and Jung-Ho Lee
‡ NKW and DHK have made equal contributions.
Abstract
The rational design of wide-temperature operating Zn–air batteries is crucial for their practical applications. However, the fundamental challenges remain; the limitation of the sluggish oxygen redox kinetics, insufficient active sites, and poor efficiency/cycle lifespan. Here we present heterointerface-promoted sulfur-deficient cobalt-tin-sulfur (CoS1−δ/SnS2−δ) trifunctional electrocatalysts by a facile solvothermal solution-phase approach. The CoS1−δ/SnS2−δ displays superb trifunctional activities, precisely a record-level oxygen bifunctional activity of 0.57 V (E1/2 = 0.90 V and Ej=10 = 1.47 V) and a hydrogen evolution overpotential (41 mV), outperforming those of Pt/C and RuO2. Theoretical calculations reveal the modulation of the electronic structures and d-band centers that endorse fast electron/proton transport for the hetero-interface and avoid the strong adsorption of intermediate species. The alkaline Zn–air batteries with CoS1−δ/SnS2−δ manifest record-high power density of 249 mW cm−2 and long-cycle life for >1000 cycles under harsh operations of 20 mA cm−2, surpassing those of Pt/C + RuO2 and previous state-of-the-art catalysts. Furthermore, the solid-state flexible Zn–air battery also displays remarkable performance with an energy density of 1077 Wh kg−1, >690 cycles for 50 mA cm−2, and a wide operating temperature from +80 to −40 °C with 85% capacity retention, which provides insights for practical Zn–air batteries.
