Manipulating Li2O2 deposition morphology by surface spin modulation of cobalt-based spinel oxide catalysts in lithium−oxygen batteries

Abstract

The lithium peroxide (Li2O2) morphology manipulated by the distribution of Li2O2 nucleation sites dramatically affects the electrochemical performance of lithium − oxygen batteries (LOBs). Cathode surface spin modulation engineering is adopted to obtain ideal Li2O2 deposition morphology, as it can effectively manipulate the nucleation site distribution. Herein, Cu1-ZnCo2O4 (Cu0.15Zn0.85Co2O4) electrocatalysts are elaborately constructed by introducing an appropriate amount of Cu2+ into the ZnCo2O4 tetrahedral sites, which successfully regulates the spin state of Co sites under the action of co-top oxygen connection. Density functional theory calculations reveal that the moderate Co dz2 orbital occupancy is obtained via spin regulation, causing the optimum adsorption capability of Cu1-ZnCo2O4 towards oxygen-containing intermediate. On the basis, the distribution of Li2O2 nucleation sites is modulated to promote the uniform deposition of small-size Li2O2 agglomerates, which possess a large contact area with the cathodic surface and a certain void structure, greatly improving reversible deposition and decomposition kinetics. As a result, LOBs catalyzed by Cu1-ZnCo2O4 offer a large specific capacity of 12984.9 mAh/g and an extended cycle stability of over 400 cycles. This work emphasizes that spin regulation engineering efficiently affects the distribution of Li2O2 nucleation sites, achieving the Li2O2 morphology modulation in LOBs.