3D Hollow α‐MnO₂ Framework as an Efficient Electrocatalyst for Lithium–Oxygen Batteries

Abstract

Lithium–oxygen (Li–O2) batteries are attracting more attention owing to their superior theoretical energy density compared to conventional Li‐ion battery systems. With regards to the catalytically electrochemical reaction on a cathode, the electrocatalyst plays a key role in determining the performance of Li–O2 batteries. Herein, a new 3D hollow α‐MnO2 framework (3D α‐MnO2) with porous wall assembled by hierarchical α‐MnO2 nanowires is prepared by a template‐induced hydrothermal reaction and subsequent annealing treatment. Such a distinctive structure provides some essential properties for Li–O2 batteries including the intrinsic high catalytic activity of α‐MnO2, more catalytic active sites of hierarchical α‐MnO2 nanowires on 3D framework, continuous hollow network and rich porosity for the storage of discharge product aggregations, and oxygen diffusion. As a consequence, 3D α‐MnO2 achieves a high specific capacity of 8583 mA h g−1 at a current density of 100 mA g−1, a superior rate capacity of 6311 mA h g−1 at 300 mA g−1, and a very good cycling stability of 170 cycles at a current density of 200 mA g−1 with a fixed capacity of 1000 mA h g−1. Importantly, the presented design strategy of 3D hollow framework in this work could be extended to other catalytic cathode design for Li–O2 batteries.

Yolk‐Shell Structured C/Mn3O4 Microspheres Derived from Metal–Organic Frameworks with Enhanced Lithium Storage Performance

“…Second, the MOF‐derived NC was served as a sacrificial template and a reductant in later hydrothermal reaction with KMnO 4 aqueous solution. [ 18 ] Specifically, carbon was oxidized into carbonate and dissolved in the solution while MnO 4 − was reduced to MnO 2 particles and deposited on the surface of NC polyhedron. [ 19 ] In this process, an interfacial void space was formed and reserved.…”

A Novel Co3O4/MnO2/C Electrode with Hierarchical Heterostructure for High‐performance Lithium‐Ion Batteries

“…In this reaction, KMnO 4 was reduced to MnO 2 deposited on the surface of samples and carbon is oxidized to carbonate dissolved in the solution. [18] Finally, the polydopamine (PDA) was formed by dopamine (DA) polymerization and then carbonized to a layer of carbon shell.…”

Superassembly of Porous Fetet(NiFe)octO Frameworks with Stable Octahedron and Multistage Structure for Superior Lithium–Oxygen Batteries

“…[ 28–30 ] Transition metal oxides, especially their high electrocatalytic composites, were widely designed and investigated as activators for various fields due to their cost effectiveness, earth abundance, tunable compounds, and structure, as well as intrinsic electrical and magnetic properties. [ 31–34 ] Zhang and co‐workers reported a perovskite‐based 3D LaFeO 3 that acted as oxygen electrode with enhanced rate capability and good stability up to 124 cycles. [ 35 ] La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 perovskite oxides were also constructed by Chi et al, which guaranteed 198 cycles at a current of 400 mA g −1 .…”