Defect-rich Zn ₂ SnO _{4− <i>x</i>} /SnO _{2− <i>x</i>} heterostructure for high sulfur utilization and uniform Li ⁺ transport toward stable Li-S full batteries

Abstract Lithium-sulfur (Li-S) batteries depend on eco-friendly sulfur cathodes coupled with lithium metal anode that can attain ultra-high energy density. However, simultaneously inhibiting the shuttling effect, accelerating the redox kinetics and regulating Li+ uniform transport are critical for realizing the industrialization of Li-S batteries. Herein, a heterostructure construction and defect engineering synergistic strategy is put forward to synthesize the defect-rich Zn2SnO4−x/SnO2−x heterostructure for both the sulfur cathode and lithium anode protection. Combined with theoretical calculations and experimental results, Zn2SnO4−x/SnO2−x heterostructure with highly exposed active sites can realize high-efficient electron transfer and decreased reaction energy barriers, promoting the multi-phase catalytic conversion of lithium polysulfides. Meanwhile, the Zn2SnO4−x/SnO2−x modified separator modulates the uniform Li+ distribution, thus suppressing dendrite growth at the anode region. As a result, the Li-S full battery based on Zn2SnO4−x/SnO2−x exhibits good feedback in terms of cycling stability (787 mAh·g−1 after 200 cycles at 0.2 C) at a high sulfur loading of 3.0 mg·cm−2.