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

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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.