Efficient Modulation of Electron Pathways by Constructing a MnO_2–x@CeO₂ Interface toward Advanced Lithium–Oxygen Batteries

Abstract

A major challenge for Li–O2 batteries is to facilely achieve the formation and decomposition of the discharge product Li2O2, and the development of an active and synergistic cathode is of great significance to efficiently accelerate its formation/decomposition kinetics. Herein, a novel strategy is presented by constructing a MnO2–x @CeO2 heterostructure on the porous carbon matrix. When it was used as a cathode for Li–O2 batteries, excellent electrochemical performances, including low overpotential, large discharge capacity, and superior cycling stability were obtained. Series theoretical calculations were conducted to reveal the mechanism for the reversible battery reactions and explain how Li2O2 interacts with the MnO2–x @CeO2 interface. Apart from the electronic ladders formed between MnO2–x 3d and CeO2 4f orbitals, which can act as a highly efficient “electron transfer expressway”, the specific adsorption of MnO2–x and CeO2 with Li2O2 molecules contributes to the enhanced anchoring force of Li2O2 and delocalization of the electron cloud on the Li–O bond. Thanks to the constructed heterostructure and synergistic effect, filmlike Li2O2 can be formed through a surface pathway, and when charging, it accelerates the separation of electrons and Li+ in Li2O2, thus achieving fast redox kinetics and low overpotential.

Engineering the Electronic Interaction between Atomically Dispersed Fe and RuO2 Attaining High Catalytic Activity and Durability Catalyst for Li‐O2 Battery

“…DFT calculation was performed to deeply explore the source of the superior catalytic activity of Fe SA -RuO 2 /HPCS cathode. Since the physical and chemical properties of cathode materials (HPCS) used in this work were basically consistent with previous work, [31,32] and the electrochemical properties and discharge products of LOBs based HPCS cathodes are also very close to our previous work, [32] only catalytic components loaded on HPCS were considered. Hence, to simulate the active sites of optimized adsorption construction between the three active sites and reactants (O 2 and LiO 2 ).…”

“…All the samples show semi-open spherical shell morphology with very thin shells (≈10 nm) and cross-linking with each other, and the sizes of these spherical shells range from tens to hundreds of nanometers, which are typical morphological characteristics of HPCS. [31][32][33] It is worth mentioning that the spherical shell surfaces on all samples are relatively smooth and no significant nanoparticles are observed, suggesting that the loaded nanoparticles should be very fine. [25] To analyze NPs on these samples, they are observed by using transmission electron microscopy (TEM).…”

“…First, HPCS derived from sodium citrate is used as the substrate carbon material. According to our previous reports, [31,32] as the cathode of Li-O 2 or Li-CO 2 batteries, HPCS have advantages such as hollow spherical shell with thin shell, abundant pore and 3D cross-linking structure, which can provide a large number of fast channels for gas/ions and have enough space to store discharge products. Subsequently, HPCS supported Ru NPs are prepared by liquid-phase reduction method, and a small amount of Fe(acac) 3 is added to deposit atomically dispersed Fe species on the surface of Ru NPs (FeRu NPs/HPCS).…”

“…The phases of the samples are identified by the XRD and Raman technique. The XRD pattern presents a broad humps peak at 25°and an inconspicuous peak locates at 43°, corresponding to the graphitic (002) and (100) planes, [31][32][33] respectively, which indicates the amorphous state of HPCS (Figure S5, Supporting Information). No other diffraction peaks are observed in the remaining samples, which may be due to the poor crystallinity of HPCS and the fine NPs in these samples.…”

Highly effective bifunctional defective cobalt phthalocyanine for photo-involved lithium-oxygen batteries

“…Furthermore, the interlacing structure can promote the rapid migration of electrons and Li + on its surface, thus achieving the reversible transition between Li 2 O 2 and O 2 . 50 The XRD patterns of the cathode at different stages were further tested (Fig. 5d) to determine the main component of the discharge product.…”