Zinc Complex-Based Multifunctional Reactive Lithium Polysulfide Trapper Approaching Its Theoretical Efficiency

The "shuttle effect" of soluble lithium polysulfides (LPS), which causes rapid capacity fading, remains a lingering issue for lithium-sulfur batteries (LSBs). Herein, we report a new type of reactive molecule-based LPS trapper, zinc acetate-diethanolamine (Zn(OAc)₂·DEA), which demonstrates a molecular efficiency of 1.8 for LPS trapping, approaching its theoretical limit of 2, which is the highest trapping capability reported so far. Furthermore, the catalytic effect of Zn²⁺·DEA on the redox of sulfur species promotes the thermodynamics for the reduction of trapped LPS and decreases the energy barrier for the oxidation of Zn(SLi)₂·DEA formed in the discharging process. LSBs using Zn(OAc)₂·DEA as the LPS trapper, binder, and redox catalyst exhibited excellent long-term cycling stability (with a capacity retention of 85% after 1000 cycles at a rate of 0.5C) and enhanced rate performance. This work demonstrated the potential of this novel type of multifunctional metal complex-based reactive molecular LPS trapper for high-capacity and stable LSBs.