Tuning the formation and decomposition of Li2O2 using noble metal-free single atomic catalysts for lithium-air batteries applications

低过电位、高度可逆的锂氧电池是实现可靠的金属空气电池技术的关键目标。在这里，我们建议使用原子分散的金属中心配位到共轭聚合物的二亚胺部分作为双功能催化剂，而不需要任何进一步的修饰来应用于Li-O2电池。聚(联亚氨基二苯二酮)(Bian)铁络合物(BP-Fe)催化剂表现出高的OER活性，在160次长时间的充放电循环中库仑效率达到100%，在250 mA/g电流下容量限制为500mAh/g。充电对应的过电位低至~1.0V，在160次循环中放电过电位几乎没有变化。当充放电倍率从100 mA/g增加到500 mA/g时，表现出良好的倍率性能，充电过电位仅增加170 mV。此外，利用该催化剂在800℃下用简易的热解方法成功地制备了含Fe的单原子催化剂。HR-TEM表征直观地证实了Fe基单原子催化剂的形成。用X射线光电子能谱对Fe-SAC的组成进行了表征。在此基础上，我们提出了一种利用边铁络合物制备Fe-SAC的简单方法。

Highly reversible Li-O2 batteries with low overpotential is the key goal to realise reliable metal air battery technology. Here we propose the use of atomically dispersed metal centres coordinated to diimine moieties of conjugated polymer as bifunctional catalysts without any further modification for Li-O2 battery applications. Poly(bisiminoacenaphthenequinone) (BIAN) iron complex (BP-Fe) catalysts showed high OER activity enabling 100% coulombic efficiency for 160 long charge discharge cycles with limitation of capacity to 500 mAh/g at 250 mA/g current. The overpotential corresponding to charging was as less as ~1.0 V with almost no change in discharge overpotential across 160 cycles. Alongside it showed commendable rate capability with just 170 mV of increment of charge overpotential when the charge-discharge rate increased from 100 to 500 mA/g. Further, using this catalyst BP-Fe polymer metal complex, single atom catalyst containing Fe was successfully prepared using a facile pyrolysis method at 800 C. HR-TEM characterization visually confirmed the formation of Fe based single atom catalyst. Composition of the Fe-SAC has been characterized using X-ray photoelectron spectroscopy. With this we present a simple way to prepare Fe-SAC using BIAN-Fe complex.