Efficient Polysulfides Adsorption and Catalytic Conversion on Germanium Dioxide for High-Performance Lithium-Sulfur...

The practical application of lithium-sulfur (Li-S) batteries has been hindered by intrinsic limitations, including the sluggish sulfur redox kinetics and the notorious polysulfide shuttle effect. To address these issues, germanium dioxide (GeO₂) as a cathode additive is selected, and the fundamental mechanism for performance improvement in Li-S batteries is systematically investigated. The spherical GeO₂@S/C composite efficiently enables high sulfur loading via abundant active sites and provides enough space to relieve the volumetric expansion of sulfur during cycling. More importantly, a range of experimental results and theoretical calculations reveal that GeO₂ could enhance electron transfer and optimize the lithium sulfide (Li₂S) deposition rate, thus accelerating lithium polysulfides (LiPSs) conversion kinetics and suppressing the shuttle effect. Electrochemical tests demonstrate that the 5% GeO₂@S/C cathode achieves the optimal electrochemical performance when the doping ratio of GeO₂ is set at 5 wt%. Specifically, the 5% GeO₂@S/C cathode delivers high initial capacity (1116.2 mAh g^-1 at 0.2 C), superior rate capability (1046.0 mAh g^-1 at 2 C), and excellent long-term cycling stability with a capacity retention of 68.6% at 1 C after 500 cycles.