Defect-rich Zn₂SnO_4−x/SnO_2−x heterostructure for high sulfur utilization and uniform Li⁺ transport toward stable Li-S full batteries

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 Zn₂SnO_4−x/SnO_2−x heterostructure for both the sulfur cathode and lithium anode protection. Combined with theoretical calculations and experimental results, Zn₂SnO_4−x/SnO_2−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 Zn₂SnO_4−x/SnO_2−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 Zn₂SnO_4−x/SnO_2−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.