Modified Graphene Sheets as Promising Cathode Catalysts for Li–O₂ Batteries: A First-Principles Study

Abstract

The Li–O2 battery is a promising energy storage device; however, it is seriously hindered by the sluggish chemical reaction of cathode catalysts. Here, we study a cathode catalyst based on B- and N-doped and BN codoping on Stone–Wales defect graphene (SWG) by first-principles calculations. Interestingly, BN codoped structure not only increases the stability of the system but also exhibits extremely low discharge and charge overpotentials. The corresponding value of overpotential for the oxygen reduction reaction is 0.23 V, and the for oxygen evolution reaction, it is 0.29 V, indicating that the BN codoped structure is an excellent cathode catalyst for Li–O2 batteries. Further analysis proves that the overpotential is strongly determined by the adsorption behavior of the intermediates in the rate-determining steps (RDS). These findings elucidate the quantitative correlations between intermediate adsorption and catalytic behavior, which provides a promising approach in designing of Li–O2 battery cathode catalysts with highly activity. In addition, taking BN-SWG as a test case, we find that BN-SWG does not promote the formation of side product Li2CO3. On the other hand, it will not lead to the decomposition of the dimethyl sulfoxide electrolytes, indicating that BN-SWG can improve the reversible cycle life without producing Li2CO3-like species in Li–O2 batteries.

Two-Dimensional Biphenylene: A Graphene Allotrope with Superior Activity toward Electrochemical Oxygen Reduction Reaction

“…It has been known that graphene is highly inert due to its delocalized π electrons. , The high ORR activity of 2D biphenylene can be rationalized from its unique electronic structures. As shown in Figure S4, the electrons are redistributed on the surface of 2D biphenylene.…”

Conformal Lithium Peroxide Growth Kinetically Driven by MoS2/MoN Heterostructures Towards High‐Performance Li−O2 Batteries

“…From our experimental observations, it is most likely that the outmost layer of MoS 2 was partially converted to MoN during the nitridation process, and thus our DFT model is composed of a top MoN layer laid over the MoS 2 substrate (Figures S8–S10). Previous studies have shown that the nucleation and growth of Li 2 O 2 are largely governed by the solvation of the LiO 2 intermediate in competition with its surface absorption on the catalytic scaffolds, [46] which is closely related to the Gutmann donor number of the electrolyte and the adsorption energy (Δ E ads ) of LiO 2 [47,48] . As shown in Figure 6(a–c), the MoS 2 (002)/MoN(200) heterostructure manifests a stronger LiO 2 binding energy (Δ E ads =−10.73 eV) than the single‐component MoS 2 (Δ E ads =−7.02 eV) and MoN (Δ E ads =−6.07 eV), supporting the preferential binding of the LiO 2 intermediate on the heterostructure, followed by the subsequent surface growth of Li 2 O 2 .…”

“…Previous studies have shown that the nucleation and growth of Li 2 O 2 are largely governed by the solvation of the LiO 2 intermediate in competition with its surface absorption on the catalytic scaffolds, [46] which is closely related to the Gutmann donor number of the electrolyte and the adsorption energy (ΔE ads ) of LiO 2 . [47,48] As shown in Figure 6(ac), the MoS 2 (002)/MoN(200) heterostructure manifests a stronger LiO 2 binding energy (ΔE ads = À 10.73 eV) than the singlecomponent MoS 2 (ΔE ads = À 7.02 eV) and MoN (ΔE ads = À 6.07 eV), supporting the preferential binding of the LiO 2 intermediate on the heterostructure, followed by the subsequent surface growth of Li 2 O 2 . This is mainly due to the electron-pulling effect from MoS 2 on MoN after the two components are brought into intimate contact, as witnessed by the calculated differential charge density profile of the MoS 2 / MoN heterostructure shown in Figure 6(d).…”

Dual-functional 3D carbon fibers decorated with Co nanoparticles and Co-Nx sites for rechargeable aprotic Li–O2 batteries

“…For example, Shi group 27 used carbon fibers coated with nanoporous gold to strengthen the adsorptive ability of Li ions, leading to a uniform Li deposition. As for cathode, carbon-based materials 28,29 are considered the most potential cathode materials for Li-O 2 batteries to date because of their good conductivity, low cost, easy pore-formation, and good ORR activity. 30,31 However, due to deficient OER activity, it is difficult for pure carbon electrodes to play a unique role in high-performance Li-O 2 batteries.…”