Phosphorene as a Catalyst for Highly Efficient Nonaqueous Li–Air Batteries

Abstract

Li–air batteries can yield exceptionally high predicted energy densities. However, for this technology to become realizable, round-trip efficiency issues and slow kinetics at the cathode require implementation of a catalyst. With design parameters not well understood and limitations on material selection, choosing an ideal catalyst is complex. In Li–air batteries, energy storage is achieved by reactions between Li and O (oxygen reduction reaction for discharge and oxygen evolution reaction for charge). Here, phosphorene is proposed as a solution through simulations of its catalytic behavior toward discharge initiated via either O2 dissociation or Li adsorption. After obtaining intermediate geometries for both nucleation paths leading to either Li2O2 or 2­(Li2O), free-energy diagrams are generated to predict the promoted discharge product of Li2O2. Furthermore, considering a final product of Li2O2, the overpotentials are predicted to be 1.44 V for discharge and 2.63 V for charge. Activation barriers for the catalytic decomposition of Li2O2 (during charge) are found to be 1.01 eV for phosphorene versus 2.06 eV for graphene. This leads to a major difference in reaction rate up to 1017 times in favor of phosphorene. These results, complemented by electronic analysis, establish phosphorene as a promising catalyst for Li–air batteries.

Phosphorus‐Based Electrocatalysts: Black Phosphorus, Metal Phosphides, and Phosphates

“…DFT simulations have provided estimates on the overpotentials and predicted the discharge product in a non‐aqueous phosphorene‐based Li–air battery. [ 56 ]…”

2 D Materials for Electrochemical Energy Storage: Design, Preparation, and Application

“…Kavalsky et al investigatedt he capability of phosphorene forL i-air batteries computationally from reaction paths of either O 2 dissociation or Li adsorption. [29] The overpotentials from the dominant mechanism are 1.44 Vf or discharge and 2.63 Vf or charge, whereas the activation barrier for decomposition of the discharge products is 1.01 eV.A ll these re- Figure 2. a-c) To pv iews of electron charge densityd ifferencefor Na adsorption at different sites:pristine stanene (a) and stanene with nanohole defects (b, c).…”

“…[82] Compared with graphene, other 2D materials are still rarely applied in Li-air batteries and this area of study remainsi mmature, with most investigations concerning theoretical predictions. [29,83] For example, Jie tal. investigated the catalytic mechanism and activity of 2D GeS and GeSe by DFT computations.…”

“…Kavalsky et al. investigated the capability of phosphorene for Li–air batteries computationally from reaction paths of either O 2 dissociation or Li adsorption . The overpotentials from the dominant mechanism are 1.44 V for discharge and 2.63 V for charge, whereas the activation barrier for decomposition of the discharge products is 1.01 eV.…”

“…prepared a single‐dispersion Co 3 O 4 ‐decorated N‐enriched graphene composite which could increase the capacity and significantly alleviate unwanted parasitic reactions in Li–O 2 batteries . Compared with graphene, other 2 D materials are still rarely applied in Li–air batteries and this area of study remains immature, with most investigations concerning theoretical predictions . For example, Ji et al.…”