ORALS

Lithium-sulfur battery is recognized as one of the most promising energy storage devices with high energy density, however, the application and commercialization are severely hindered by both the practical gravimetric and volumetric energy densities due to the low sulfur content and tap density with light-weight and nonpolar porous carbon materials as sulfur host. <br />Herein, we have developed some metal oxides and oxyhydroxides, i.g. NiCo2O4, NiFe2O4, and CoOOH, as carbon-free sulfur immobilizer to fabricate sulfur-based composite as cathode for lithium-sulfur battery. These non-carbon matrix materials for sulfur can accelerate the catalytic conversion kinetics of lithium polysulfides by strong chemical interaction, successfully alleviating the shuttle isuue and leading to a good cycle stability. The S/NiCo2O4 composite presents a high gravimetric capacity of 1125 mAh g-1-composite at 0.1C rate, and a low fading rate of 0.039% per cycle over 1500 cycles at 1C rate. In particular, the S/NiCo2O4 composite with the high tap density of 1.66 g cm-3 delivers a large volumetric capacity of 1867 mAh cm-3-composite, almost twice that of the conventional S/carbon composite. With ultrahigh sulfur content of 91.8 wt% and tap density of 1.26 g cm-3, the sulfur/CoOOH composite delivers high gravimetric capacity and volumetric capacity of 1199.4 mAh g-1-composite and 1511.3 mAh cm-3 at 0.1C rate, respectively. Meanwhile, the sulfur-based composite presents satisfactory cycle stability with a slow capacity decay rate of 0.09% per cycle within 500 cycles at 1C rate. The works provide a new strategy to realize the combination of gravimetric energy density, volumetric energy density and good electrochemical performance of lithium-sulfur battery.

References:
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