Deciphering the eg occupancy descriptor on perovskite oxides for lithium-sulfur batteries
The partially filled d orbital of transition metal-based catalysts demonstrate excellent catalytic activity against polysulfides. However, an appropriate descriptor to reveal their structure-activity relationship is lacked. This study proposes a quantitative relationship between the e g occupancy of perovskite oxides and polysulfide catalytic activity, serving as an activity descriptor. LaCoO 3 , with a moderate e g occupation (t 2g 5 e g 1.08 ), demonstrates effective polysulfide anchoring and facilitated redox kinetics conversion compared to LaCrO 3 (t 2g 3 e g 0 ) and LaFeO 3 (t 2g 3 e g 2 ), showcasing exceptional catalytic performance. The degree of e g occupancy significantly influences the polysulfides adsorption strength, with empty or fully filled e g orbitals resulting in either strong or weak adsorption, respectively. LaCoO 3 -based batteries exhibit remarkable reversible capacity over 700 cycles at 1.0C, with a minimal capacity fading rate of 0.065 % per cycle. This work elucidates the crucial role of e g descriptor for evaluating the adsorption and conversion on polysulfides, offering insights into the development of innovative lithium-sulfur electrocatalysts.
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