Pushing Lithium-Sulfur Batteries towards Practical Working Conditions through a Cathode-Electrolyte Synergy.

ABSTRACT

The commercialization of lithium-sulfur (Li-S) batteries is still hindered by the unsatisfactory cell performance under practical working conditions, which is mainly caused by the sluggish cathode redox kinetics, severe polysulfide shuttling, and poor Li stripping/plating reversibility. Herein, we report an effective strategy by combining Se-doped S hosted in an ordered macroporous framework with a highly fluorinated ether (HFE)-based electrolyte to simultaneously address the aforementioned issues in both cathode and anode. A reversible and stable high areal capacity of >5.4 mAh cm-2 with high Coulombic efficiency >99.2 % can be achieved under high areal Se/S loading (5.8 mg cm-2 ), while the underlying mechanism was further revealed through synchrotron X-ray probes and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The practical application potential was further evaluated at low (0 °C) and high (55 °C) temperatures under high areal Se/S loading (>5.0 mg cm-2 ) and thin Li metal (40 µm).