Freestanding MOF-Derived Honeycomb-Shape Porous MnOC@CC as an Electrocatalyst for Reversible LiOH Chemistry in Li-O₂ Batteries

Abstract

In rechargeable Li-O 2 batteries, the electrolyte and the electrode are prone to be attacked by aggressive intermediates (O 2 − and LiO 2 ) and products (Li 2 O 2 ), resulting in low energy efficiency. It has been reported that in the presence of water, the formation of low-activity LiOH is more stable for electrolyte and electrode, effectively reducing the production of parasitic products. However, the reversible formation and decomposition of LiOH catalyzed by solid catalysts is still a challenge. Here, a freestanding metal−organic framework (MOF)-derived honeycomb-shape porous MnOC@CC cathode was prepared for Li-O 2 batteries by in situ growth of urchin-like Mn-MOFs on carbon cloth (CC) and carbonization. The battery with the MnOC@CC cathode exhibits an ultrahigh practical discharge specific capacity of 22,838 mAh g −1 at 200 mA g −1 , high-rate capability, and more stable cycling, which is superior to the MnOC powder cathode. X-ray diffraction and Fourier transform infrared results identify that the discharge product of the batteries is LiOH rather than highly active Li 2 O 2 , and no parasitic products were found during operation. The MnOC@CC cathode can induce the formation of flower-like LiOH in the presence of water due to its unique porous structure and directional alignment of Mn−O centers. This work achieves the reversible formation and decomposition of LiOH in the presence of water, offering some insights into the practical application of semiopen Li-O 2 batteries.

In Situ Growth of Amorphous MnO2 on Graphite Felt via Mild Etching Engineering as a Powerful Catalyst for Advanced Vanadium Redox Flow Batteries

“…The Mn 2p spectra of AMO@GF showed two peaks at 654.0 and 642.3 eV, corresponding to the binding energies of Mn 2p 3/2 and Mn 2p 1/2 , respectively (Figure e). The splitting width between the two peaks is 11.68 eV, confirming that the oxidation state of Mn on AMO@GF is Mn 4+ (MnO 2 ). , In addition, the O 1s spectra of AMO@GF possessed three characteristic peaks, as shown in Figure f, which was assigned to Mn–O–Mn (529.8 eV), Mn–O–H (531.6 eV), and C–O (533.0 eV), respectively. , …”

Asymmetric Catalytic Site Driving LiOH Chemistry for Li–O2 Batteries Based on Cationic Vacancy-Derived Single-Atom Spinel

“…Although LiOH-based Li–O 2 batteries have certain advantages compared to Li 2 O 2 -based Li–O 2 batteries, there is still significant room for improvement in various electrochemical properties of LiOH-based Li–O 2 batteries, and the development of catalysts based on LiOH reactions is one of the medicines to address the symptoms. Currently reported catalysts for LiOH reactions include both liquid-state and solid-state catalysts, each playing distinct roles in Li–O 2 batteries while also possessing their own significant therapeutic effects. − Grey et al introduced an ionic liquid into a glyme-based electrolyte containing LiI and water, demonstrating a reversible LiOH-based Li–O 2 battery cycle operated by a 4e – /O 2 process with a charging overpotential below 3.5 V . Wu et al suggest that the main product in Co 3 O 4 nanosheet-based cathodes is LiOH, with resulting LiOH also demonstrating reversible formation/decomposition behavior .…”

Terephthalic Acid Intercalated CoNi‐LDH Materials for Improved Li–O2 Battery

“…[ 2 ] Huang et al. [ 3 ] prepared a freestanding metal–organic framework (MOF)‐derived honeycomb‐shape porous MnOC@CC cathode of Li–O 2 batteries, whose discharge product is low activity LiOH, is more stable for electrolytes and electrodes. Zhao et al.…”