Tailoring FeP with a Hollow Urchin Architecture for High-Performance Li-S Batteries

The conversion chemistry of lithium-sulfur provides a high energy density (2600 Wh/kg), enabling lithium-sulfur batteries to be a promising energy storage system. Nevertheless, the dissolved lithium polysulfide intermediates tend to diffuse in the electrolyte (called shuttle effect), which leads to serious degradation both in the cathode (S) and anode (Li), resulting in the rapid decay of capacity. Herein, we propose a hollow urchin-like FeP as the sulfur host, which not only can chemically absorb polysulfide to suppress the shuttle effect, ensuring the stable cycling, but also holds a catalytic ability to Li-S, contributing to the fast kinetics. Additionally, such an architecture with high curvature and reduced weight allows more exposed active surfaces and higher sulfur loading. As a consequence, the Li-S battery with an FeP functional separator interlayer can achieve a durable cycling capacity of 692.0 mAh g(-1) at 1 C over the 200th cycle. When employed as a sulfur host, FeP exhibits rate capacities of 1107.3, 964.0, 790.1, 647.1, and 538.7 mAh g(-1) at 0.1, 0.2, 0.5, 1, and 2 C, respectively. Although evaluated with a sulfur loading of 3.5 mg cm(-2), the electrode still displays a high areal capacity of 2.2 mAh cm(-2) and a nearly linear relationship with sulfur loading.

Automated summary

Using hollow urchin-like FeP as a sulfur host can effectively suppress the shuttle effect, exhibit catalytic ability to Li-S, and enhance the cycling stability and kinetics of lithium-sulfur batteries.