The sluggish sulfur reduction reaction (SRR) kinetics of lithium-sulfur (Li-S) batteries seriously limits the development of Li-S batteries. The initial reduction of solid (S8) to liquid (soluble Li2Sn (4≤n≤8)) is relatively easy due to the low activation energy, whereas the subsequent conversion of liquid (soluble Li2Sn) to solid (insoluble Li2S2/Li2S) has much higher activation energy, which leads to the accumulation of Li2Sn and exacerbates the shuttle effect of Li2Sn. Therefore, establishing one selective catalyst that decelerates the previous solid-liquid reaction and accelerates the subsequent liquid-solid reaction is essential for rational tailoring of the SRR for improved performance of Li-S batteries, but it represents a daunting challenge. Here, considering that the indium oxide catalyst possesses selective catalytic properties and drawing inspiration from the theoretical calculations, In2O3 nanospheres containing phosphorus doping and oxygen vacancies (P-OV-In2O3 NSs) are designed and synthesized as a selective catalyst for Li-S batteries. Contributed by the unique selective catalytic capability, the batteries using P-OV-In2O3 NSs modified separators exhibit excellent sulfur utilization, superb rate performance (656 mAh g-1 at 5.0 C), and low-capacity decay rate of about 0.069% per cycle over 500 cycles at 1.0 C.
Keywords: indium oxide; oxygen vacancy; phosphorus doping; selective catalysis; sulfur reduction reaction.
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