Unlocking Enhanced Redox Dynamics: The Power of a Bifunctional Catalytic Zinc Phosphide Interface in Full Cell and Pouch Lithium–Sulfur Batteries
Anoushka K. Das, Poonam Yadav, Tushar Singh Verma, M Thripuranthaka, Saïlaja Krishnamurty, Manjusha V. Shelke
Abstract
Lithium–sulfur (Li–S) batteries face significant challenges, such as polysulfide dissolution, sluggish reaction kinetics, and lithium anode corrosion, hindering their practical application. Herein, we report a highly effective approach using a zinc phosphide (ZnP 2 ) bifunctional catalyst to address these issues. The ZnP 2 catalyst effectively anchors lithium polysulfides (LiPSs), catalytically reactivates them, and enhances lithium-ion diffusion. Utilizing a ZnP 2 -modified separator in a Li–S half-cell achieves an impressive initial capacity of 1145.4 mAh g –1, retaining 954 mAh g –1 and 99.8% Coulombic efficiency after 100 cycles, compared to the pristine separator. The underlying reaction mechanisms are thoroughly investigated through post-mortem analyses and density functional theory (DFT) calculations. Moreover, a Li–S full cell with an E/S ratio of 10 μL mg –1 demonstrates stable cycling performance, achieving an initial capacity of 797.5 and 534 mAh g –1 after 100 cycles at 0.1C, with a negative-to-positive mass ratio of 3:1. Additionally, the real-world feasibility of lightweight and flexible Li–S pouch batteries with ZnP 2 -modified separators is explored, showing a stable performance over 100 cycles at 0.1C with 80% capacity retention. This engineered separator can be integrated with advanced sulfur cathodes to create high-energy-density, stable Li–S batteries for commercial applications.