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.