True Reaction Sites on Discharge in Li–O₂ Batteries

Abstract

In the pursuit of an advanced Li−O 2 battery, the true reaction sites in the cathode determined its cell performance and the catalyst design. When the first layer of insulating Li 2 O 2 solid is deposited on the electrode substrate during discharging, the following O 2 reduction to Li 2 O 2 could take place either at the electrode|Li 2 O 2 interface or at the Li 2 O 2 |electrolyte interface. The mechanism decides the strategies of catalyst design; however, it is still mysterious. Here, we used rotate ring-disk electrode to deposit a dense Li 2 O 2 film and labeled the Li 2 O 2 product with 16 O/ 18 O isotope. By identification of the distribution of the Li 2 16

Transition Metal Phthalocyanines as Redox Mediators in Li–O2 Batteries: A Combined Experimental and Theoretical Study of the Influence of 3d Electrons in Redox Mediation

“…Initial reports of redox mediation in lithium–oxygen systems included additives that helped in reversible charge–discharge chemistry in nonaqueous and aqueous electrolytes. , These are electron-transfer mediators. The ability to complex with oxygen and thus, increase oxygen solubility in the electrolyte, was soon identified as a desired feature in RMs. , Very recently, we demonstrated a proof-of-concept of the synergistic role of electron transfer and oxygen binding, by using the mammalian oxygen transporting protein hemoglobin, as an RM in lithium–oxygen batteries …”

“…The ability to complex with oxygen and thus, increase oxygen solubility in the electrolyte, was soon identified as a desired feature in RMs. 10,11 Very recently, we demonstrated a proof-of-concept of the synergistic role of electron transfer and oxygen binding, by using the mammalian oxygen transporting protein hemoglobin, as an RM in lithium−oxygen batteries. 12 Structurally very similar to iron porphyrin (haem), iron phthalocyanine was the first reported organometallic redox mediator that also showed reversible oxygen shuttling ability.…”

The key to improving the performance of Li–air batteries: recent progress and challenges of the catalysts

“…It is the theoretical basis for the design of lithium-air batteries. 69 In addition to O 2 , there is also H 2 O in the air, and gases such as CO 2 and N 2 can also react with lithium. Therefore, if the air is directly introduced to participate in the reaction, LiOH, Li 2 CO 3 , and Li 3 N will also appear in the discharge products.…”

Reacquainting the Sudden-Death and Reaction Routes of Li–O2 Batteries by Ex Situ Observation of Li2O2 Distribution Inside a Highly Ordered Air Electrode

“…Similarly, it seems that CNTs pass through the Li 2 O 2 particles based on the SEM and transmission electron microscopy images of Shao-Horn et al The reaction interface is thus particularly important and is usually investigated by isotope-labeling techniques. Shen et al indicated that 75% of the active sites are at the electrode/Li 2 O 2 interface in the surface route . Lu et al suggested that new Li 2 O 2 is formed on the top (Li 2 O 2 /electrode interface) of toroidal Li 2 O 2 in the solution route .…”

“…Shen et al indicated that 75% of the active sites are at the electrode/ Li 2 O 2 interface in the surface route 51. Lu et al suggested that new Li 2 O 2 is formed on the top (Li 2 O 2 /electrode interface) of toroidal Li 2 O 2 in the solution route.…”