Li–O₂ batteries are considered as one of the promising beyond Li-ion battery technologies owing to their high energy density. But, their poor cycle life due to sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) hinder the commercialization of this technology. Hence, fabrication of highly efficient ORR and OER catalysts is of paramount importance in order to improve the cyclic stability and longevity of this device. Herein, we discuss systematically the synthesis and electrochemical analysis of such bifunctional perovskite catalysts, namely, pristine CaMnO₃ and its defect induced counterpart. When evaluated as a cathode catalyst in a Li–O₂ battery along with a redox mediator LiI, the oxygen deficient CaMnO₃ gives an improved cycle life reported at a high current rate of 500 mA g^–1 with a capacity of 500 mA h g^–1 in comparison with similar catalysts reported in the literature. Introduction of defects in the pristine framework predominantly improves the catalytic activity by lowering the overpotential. The presence of oxygen vacancies creates mixed-valence states of Mn³⁺/Mn⁴⁺ which modify the electronic structure, resulting in the improved catalytic activity. Comprehensive phase and compositional analysis confirm the formation of the desired defect-induced structure with improved catalytic activity toward ORR and OER which is elaborated with electrochemical analysis.

中文翻译：

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缺陷在低成本钙钛矿催化剂中对锂氧电池中ORR和OER的作用

Li-O ₂电池由于其高能量密度而被认为是超越锂离子电池技术的有前途的一种。但是，由于氧气还原反应（ORR）和氧气释放反应（OER）缓慢而导致的循环寿命很短，这阻碍了该技术的商业化。因此，为了提高该装置的循环稳定性和寿命，制造高效的ORR和OER催化剂至关重要。在本文中，我们系统地讨论了这种双官能钙钛矿催化剂，即原始CaMnO ₃及其缺陷诱导的对应物的合成和电化学分析。当与氧化还原介体LiI一起用作Li–O ₂电池中的阴极催化剂时，缺氧的CaMnO ₃与文献中报道的类似催化剂相比，在500 mA g ^–1的高电流速率下具有500 mA hg ^–1的容量可以提供更长的循环寿命。在原始骨架中引入缺​​陷主要是通过降低过电位来提高催化活性。氧空位的存在产生了Mn ³⁺ / Mn ^4+的混合价态，从而改变了电子结构，从而提高了催化活性。全面的相和组成分析证实了所需的缺陷诱导结构的形成，并具有改进的对ORR和OER的催化活性，这是用电化学分析方法完成的。