Quantum Spin Exchange Interactions to Accelerate the Redox Kinetics in Li-S Batteries.

Spin-engineering with electrocatalysts have been exploited to suppress the "shuttle effect" in Li-S batteries. Spin selection, spin-dependent electron mobility and spin potentials in activation barriers can be optimized as quantum spin exchange interactions leading to a significant reduction of the electronic repulsions in the orbitals of catalysts. Herein, we anchor the MgPc molecules on fluorinated carbon nanotubes (MgPc@FCNT), which exhibits the single active Mg sites with axial displacement. According to the density functional theory calculations, the electronic spin polarization in MgPc@FCNT not only increases the adsorption energy toward LiPSs intermediates but also facilitates the tunneling process of electron in Li-S batteries. As a result, the MgPc@FCNT provides an initial capacity of 6.1 mAh cm even when the high sulfur loading is 4.5 mg cm, and still maintains 5.1 mAh cm after 100 cycles. This work provides a new perspective to extend the main group single-atom catalysts enabling high-performance Li-S batteries.