State Key Laboratory of Material Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology , Wuhan, Hubei 430074, People's Republic of China.
ACS Appl Mater Interfaces. 2015 Mar 4;7(8):4947-54. doi: 10.1021/am509143t. Epub 2015 Feb 24.
Tremendous efforts have been devoted to exploring various Li-O2 cathode catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). However, most of the high-activity ORR/OER catalysts can also accelerate side-reactions, such as electrolyte degradation on cycling. To address this issue, we change our strategy from pursuing highly active catalysts to developing stable cathodes that are compatible with the electrolyte. In this work, hierarchical mesoporous ZnO/ZnFe2O4/C (ZZFC) nanocages are synthesized from the templates of metal-organic framework (MOF) nanocages. Such ZZFC nanocages have lower ORR/OER catalytic activity as compared with the widely used catalysts for fuel cells, but they do not catalyze the degradation of organic electrolyte during operation. Furthermore, the optimized porosity and conductivity can fit well the needs of the Li-O2 cathode. When employed in a Li-O2 battery, the ZZFC cathode delivers a primary discharge/charge capacity exceeding 11 000 mAh g(-1) at a current density of 300 mA g(-1) and an improved cyclability with capacity of 5000 mAh g(-1) for 15 cycles. The superior electrochemical performance is ascribed to the hierarchical porosity and little degradation of the organic electrolyte.
研究人员在探索各种用于氧还原反应（ORR）和氧析出反应（OER）的锂-氧 2 阴极催化剂方面付出了巨大努力。然而，大多数高活性的 ORR/OER 催化剂也会加速副反应，例如循环过程中电解质的降解。为了解决这个问题，我们改变策略，从追求高活性催化剂转向开发与电解质兼容的稳定阴极。在这项工作中，采用金属有机框架（MOF）纳米笼作为模板，合成了具有分级介孔结构的 ZnO/ZnFe2O4/C（ZZFC）纳米笼。与用于燃料电池的广泛使用的催化剂相比，这种 ZZFC 纳米笼具有较低的 ORR/OER 催化活性，但在运行过程中不会催化有机电解质的降解。此外，优化的孔隙率和电导率可以很好地满足锂-氧 2 阴极的需求。在锂-氧 2 电池中，当电流密度为 300 mA g-1 时，ZZFC 阴极的首次放电/充电容量超过 11000 mAh g-1，在 15 次循环中具有 5000 mAh g-1 的改进循环稳定性。优异的电化学性能归因于分级孔隙率和有机电解质的少量降解。
