The Surface Electronic Structure Reconstruction of Co_2.85Mn_0.15O₄ with High Active Sites for High-Efficient Lithium–Oxygen Batteries

Abstract

Spinel structure Co 3 O 4 has been used as cathode catalysts for lithium−oxygen batteries, because of the structural stability, abundant oxygen vacancies, and adjustable Co 3+ /Co 2+ ratio. Most reports focused on adjusting the anion−cation ratio and coordination state in Co 3 O 4 to enhance its ORR and OER activities. Based on this, we interfered with the distribution of Co 2+ /Co 3+ by introducing Mn 3+ . Li 2 O 2 was detected as a discharge product by in situ characterization methods, but the charging voltage was only 3.25 V. During charge and discharge, Mncontaining Co 3 O 4 has a higher reversible shift of Co 3+ /Co 2+ , and this surface electron reconstitution effect leads to an extremely low overpotential (0.29 V). The surface electronic structure modified strategy and reversibility verification method could be a positive significance in the application of lithium−oxygen batteries, especially for reducing the use of noble metal catalysts.

Modulation Strategies and Activity Descriptors of Spinel Electrocatalysts for Lithium−Oxygen Batteries

“…Co 2.85 Mn 0.15 O 4 as an efficient cathode catalyst was prepared for LOBs by employing a simple solvothermal calcination strategy. [21] As seen in Figure 3e, Co 2.85 Mn 0.15 O 4 features an atypical spinel stabilized structure, in which Mn atoms replace some of the Co 3 + octahedral sites, not only enhancing the extremely high surface Co 3 + concentration, but also facilitating the surface aggregation of Mn-active species. As a result, surface electron reconstitution effect is more likely to occur during subsequent charging and discharging processes.…”

“…(e-i) Reproduced with permission. [21] Copyright 2023, American Chemical Society. (j-q) Reproduced with permission.…”

“…A feasible strategy to address these issues and enhance the electrochemical performance of LOBs, more in-depth exploration and investigation of efficient cathode catalysts. [20][21][22] Generally, cathode catalysts used in LOBs include noble metals, carbon materials, and non-noble metal catalysts. Noble metals, due to their intrinsic half-filled antibonding states, readily enable the modulation of the adsorption strength between the reaction intermediates and catalysts, thus significantly optimizing the ORR/OER catalytic activity.…”

“…Copyright 2021, Elsevier. (e-i) Reproduced with permission [21]. Copyright 2023, American Chemical Society.…”