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

低过电位的高可逆锂氧电池是实现可靠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合二亚胺部分的共轭聚合物作为双功能催化剂，无需任何进一步的修饰，用于锂氧电池。聚二亚胺苊马醌（BIAN）铁络合物（BP-Fe）催化剂表现出较高的OER活性，在250 mA/g电流下，在160次长充放电循环中具有100%的库仑效率，容量限制为500 mAh/g。充电时的过电位小于~1.0 V，放电过电位在160次循环中几乎没有变化。此外，当充放电倍率从100 mA/g增加到500 mA/g时，其电荷过电位仅增加170 mV，具有良好的倍率性能。进一步，利用该催化剂BP-Fe聚合物金属配合物，在800℃下采用易热解法成功制备了含Fe的单原子催化剂，hrtem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，我们提出了一种用BIAN-Fe配合物制备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.