Crystal Phase Conversion on Cobalt Oxide: Stable Adsorption toward LiO₂ for Film‐Like Discharge Products Generation in Li‐O₂ Battery

Abstract

Regulating the structure and morphology of discharge product is one of the key points for developing high performance Li‐O2 batteries (LOBs). In this study, the reaction mechanism of LOB is successfully controlled by the regulated fine structure of cobalt oxide through tuning the crystallization process. It is demonstrated that the cobalt oxide with lower crystallinity shows stronger affinity toward LiO2, inducing the growth of film‐like LiO2 on the electrode surface and inhibiting the further conversion to Li2O2. The batteries catalyzed by the lower crystallinity cobalt oxide hollow spheres which pyrolyzed from ZIF‐67 at 260 °C (ZIF‐67‐260), go through the generation and decomposition of amorphous film‐like LiO2, which significantly reduces the charge overpotential and improves the cycle life. By contrast, the ZIF‐67 hollow spheres pyrolyzed at 320 °C (ZIF‐67‐320) with better crystallinity are more likely to go through the solution‐mediated mechanism and induce the aggregation of discharge product, resulting in the sluggish kinetics and limited performance. The combined density functional theory data also directly support the strong relationship between the adsorption toward LiO2 by the electrocatalyst and the battery performance. This work provides an important way for tuning the intermediate and constructing the high‐performance battery system.

2D Co-doped MnCr2O4 nanosheets as efficient bifunctional cathode materials for long-life Li–O2 batteries

“…4,5 One of the most effective strategies to address these issues is to develop inexpensive and efficient cathode catalysts. 6,7 With the progress of research, cathode catalysts have become an important part of LOBs, among which carbon materials, 8,9 noble metals, 10,11 and non-noble metal compounds [12][13][14][15] have been widely studied to improve the performance of batteries.…”

Performance of Air Electrode Catalysts in the Presence of Redox Mediators for High-Capacity Li–O2 Batteries

“…First, various catalysts, which were reported to show high capacities at low current densities, were investigated at a high current density (0.4 mA cm –2 ) and a high areal capacity (4 mAh cm –2 ) in the presence of RMs using KBFSs with large areal weight and were compared with the pristine KBFS. The chosen catalysts were N-doped KBFSs, which have been reported to increase ORR activity, − sulfide catalysts, which have attracted a lot of attention in recent years, − Co catalysts, which have been reported to have high ORR activity, − and other precious metal catalysts like RuO 2 catalysts, which have been reported to show high performance, − Ir catalysts, ,− and PtCo catalysts. , Then, we tried to clarify the characteristics of the catalysts that showed good performance.…”

Single‐Atom‐Mediated Spinel Octahedral Structures for Elevated Performances of Li‐Oxygen Batteries

“…[23,24] Noble metals have been extensively used, for their excellent catalytic activities and conductivities, [25][26][27][28][29] yet their low abundances and high costs set prohibitive limits for largescale application. Cobalt oxide, as a representative transition metal oxide, has a flexible redox chemistry and high electron transmission efficiency, [30][31][32] and therefore has already shown great potentials to work as the cathode catalyst for LOBs. [33][34][35] At the same time, the construction of a catalyst with large specific surface area and hollow porous structure is conducive to improving the mass transfer efficiency of the battery, [36][37][38] exposing more catalytic active sites, providing more nucleation sites for Li 2 O 2 , and directing the morphology of Li 2 O 2 .…”