Modulating the Coordination Environment of Single Fe Atoms with Enhanced Electrocatalytic Performance for Advanced Li─S Batteries

Abstract

Involving electrocatalysts to increase the sluggish reduction reaction kinetics of soluble lithium polysulfides is evidenced effective in inhibiting the shuttle effect and enhancing the cycle stability of Li─S batteries. In this work, phosphorus‐coordinated single Fe atoms (FePC) are synthesized based on the coordination environment modulation strategy. Combining with experimental and theoretical methods, the well‐designed FePC with plane‐symmetric Fe─P4─C configuration exhibits strengthened catalytic effect toward reversible conversion between LiPS and Li2S, that endows S@FePC cathodes with superior electrochemical performance. The prepared S@FePC coin cells achieve prolonged cyclic stability of over 1000 cycles at 1C with a high capacity retention of 77.8%. Even at high sulfur loading (5.7 mg cm−2) and low E/S ratio (6.2 µL mgS−1), the areal capacity reached 6.0 mAh cm−2 and 88.3% of it is retained after 100 cycles at 0.1 C. Moreover, the prepared 0.6 Ah S@FePC pouch cell exhibits higher capacity retention of 76.3% after 100 cycles at 0.1 C compared with S@FeNC. Meanwhile, the prepared 8Ah S@FePC pouch cell approaches a high specific energy of 401 Wh kg−1 at 0.1 C proving its practicability. The obtained outcomes may guide the future design and development of SACs with higher catalytic activity for practical Li─S batteries.