Confining Li2O2 in tortuous pores of mesoporous cathodes to facilitate low charge overpotentials for Li-O2 batteries

Ru-Embedded Highly Porous Carbon Nanocubes Derived from Metal–Organic Frameworks for Catalyzing Reversible Li2O2 Formation

“…Composing the highly porous carbon scaffold with oxygen conversion catalysts should effectively reduce charging and discharging overpotentials by promoting reversible Li 2 O 2 formation (ORR) and decomposition (OER). The thus reduced polarization can therefore effectively mitigate side reactions from carbon and electrolyte decomposition, , which is indeed evidenced by the above DEMS study. Above all, the DEMS results here provided concrete evidence for the reversible oxygen conversion catalyzed by Ru@MCN, thanks to its highly porous structure embedding abundant Ru sites that synergizes in reducing overpotentials, suppressing parasitic reactions, accommodating reaction products, and promoting mass and charge transportation.…”

“…To date, growing efforts have been witnessed to engineer suitable catalysts for addressing the above-mentioned Li 2 O 2 chemistry in LOBs, including carbon composites, − noble metals/alloys, − transitional metal oxides, − perovskites, − and so forth. Ideally, a competent oxygen-cathode catalyst should possess several basic attributes, including high electric conductivity for charge transfer, high gas permeability for O 2 diffusion, high porosity for accommodating solid reaction products, and high catalytic potency for lowering charge/discharge overpotentials .…”

Nanoarchitectonics of the cathode to improve the reversibility of Li–O2 batteries

“…During the subsequent charge, Li 2 O 2 can be reversibly decomposed to Li + and O 2 by the oxygen evolution reaction (OER) [ 3 – 6 ]. Considering these reaction mechanisms of LOBs, the cathode should have a large surface area to offer abundant active sites for the electrochemical reactions and a large pore volume for effective accommodation of Li 2 O 2 [ 7 – 8 ]. If accumulated Li 2 O 2 is not completely decomposed during the charge, the reaction sites and diffusion pathways of electrolytes and oxygen species are blocked, resulting in a decrease of the electrochemical performance of LOBs [ 9 ].…”

Nitrogen-Coordinated CoS2@NC Yolk–Shell Polyhedrons Catalysts Derived from a Metal–Organic Framework for a Highly Reversible Li-O2 Battery

“…Recently, lithium–oxygen batteries (LOBs) have attracted large-scale research owing to their theoretical gravimetric energy density of 11,148 W h kg –1 (based on anode metal), which is practically an order of magnitude higher than that of other chemical batteries. − Unlike traditional LIBs, LOBs abandon intercalation electrodes and Li + ions react directly with O 2 from the air as an anode that is not inside the system, the novel structure making it thinner than LIBs, which is beneficial to the development of SWDs. Although the advancement and pragmatic application of LOBs are gravely impeded by many factors, such as slack kinetics of the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) and electrochemical performance. − In the system, the OER/ORR inefficiency stems mainly from the nucleophilic attack, superoxide radical attack, and the novel 1 O 2 -induced reactions, which are the main mechanisms that bring about the formation of the byproducts (such as Li 2 CO 3 and LiOH) and cause electrolyte decomposition .…”