Oxygen Vacancy‐Mediated Growth of Amorphous Discharge Products toward an Ultrawide Band Light‐Assisted Li–O₂ Batteries

Abstract

Photoassisted electrochemical reaction is regarded as an effective approach to reduce the overpotential of lithium–oxygen (Li–O2) batteries. However, the achievement of both broadband absorption and long term battery cycling stability are still a formidable challenge. Herein, an oxygen vacancy‐mediated fast kinetics for a photoassisted Li–O2 system is developed with a silver/bismuth molybdate (Ag/Bi2MoO6) hybrid cathode. The cathode can offer both double advantages for light absorption covering UV to visible region and excellent electrochemical activity for O2. Upon discharging, the photoexcited electrons from Ag nanoplate based on the localized surface plasmon resonance (LSPR) are injected into the oxygen vacancy in Bi2MoO6. The fast oxygen reaction kinetics generate the amorphous Li2O2, and the discharge plateau is improved to 3.05 V. Upon charging, the photoexcited holes are capable to decompose amorphous Li2O2 promptly, yielding a very low charge plateau of 3.25 V. A first cycle round‐trip efficiency is 93.8% and retention of 70% over 500 h, which is the longest cycle life ever reported in photoassisted Li–O2 batteries. This work offers a general and reliable strategy for boosting the electrochemical kinetics by tailoring the crystalline of Li2O2 with wide‐band light.

Tailored Plasmonic Ru/OV-MoO2 on TiO2 Catalysts via Solid-Phase Interface Engineering: Toward Highly Efficient Photoassisted Li–O2 Batteries with Enhanced Cycling Reliability

“…Moreover, the peak at 529.5 eV in the O 1s spectra of RMST/CC (Figure e) indicated the presence of Ru–O, while the peak at 530.5 eV in the O 1s spectra of Ru/O V -MT/CC implied the presence of Mo–O . In addition, the peak at 531.3 eV in the O 1s spectrum of Ru/O V -MT/CC suggested the presence of oxygen vacancies, which is a typical feature of defect-rich oxides. ,, Additionally, Ru/O V -MT shows a characteristic EPR signal at g = 2.003, which provides clear evidence for the existence of oxygen vacancies in the material (Figure S8). , As shown in Figure f, RMST/CC clearly showed the typical signals of the RuO 2 component, Ru 3d 5/2 (281.38 eV) and Ru 3d 3/2 (285.18 eV) .…”

“…Generally, photocatalytic activity can be favorably adjusted through constructing heterojunction systems and defect engineering . Moreover, coupling plasmonic metals with suitable semiconductors such as Ag/Bi 2 MoO 6 , Au/NV-C 3 N 4 , and TNAs-AuNPs extends light-harvesting and plasmonic enhancement effects and is very effective for both ORR and OER of Li–O 2 cells with promising results because when light is incident on nanoparticles made of noble metals, if the incident photon frequency matches the overall vibration frequency of the noble metal nanoparticles or metal conduction electrons, the nanoparticles or metal will have strong absorption of photon energy. Also, the decay of excited localized surface plasmon resonance (LSPR) can produce hot electrons and holes, which initiate various chemical reactions. − However, precious metals are costly and easy to agglomerate .…”

“…Notably, the high concentration of free electrons and low resistivity of MoO 2 make them have a strong LSPR effect . The doping of oxygen vacancies and loading of metal nanoparticles will promote charge transfer and improve the LSPR effect of MoO 2 . ,,− Controlled doping in semiconductors is of vital importance in developing novel materials. − Moreover, interface engineering is of crucial significance for functional devices. − Therefore, it is desirable to design a facile method to localize the defects and metal catalytic centers in MoO 2 .…”

Conformal Lithium Peroxide Growth Kinetically Driven by MoS2/MoN Heterostructures Towards High‐Performance Li−O2 Batteries

“…Furthermore, XPS taken on the discharged cathode revealed a prominent Li 1s peak at 55.0 eV (Figure 4b), suggesting that the amorphous discharge product comprises Li 2 O 2 . [14,38] Upon recharging, the morphology of MoS 2 /MoN@CC gradually reverted to its initial state where no visible deposits can be found (Figure 4a-IV, V and VI). Both the XRD peaks of MoS 2 and MoN reemerged after recharging to 1.0 mAh cm À 2 (Figure 5a), accompanied by the disappearance of Li 1s peak in XPS (Figure 4b).…”

“…[10][11][12] On the other hand, amorphous Li 2 O 2 in the format of thin film or grainy domains yielded through the "surface-growth" mechanism are easier to decompose during OER in virtue of the more intimate contact with the catalytic scaffold, leading to enhanced charge/ discharge kinetics and reversibility. [13][14][15] However, excessive accumulation of the insulating Li 2 O 2 would soon mask the active sites and blockade the charge conduction path, reducing not only the battery capacity, but also the cycling life. Therefore, it is imperative to search for suitable material chemistry and architecture to endow high charge transitivity, catalytic activity, and discharge product accommodation for solving such dilemma of capacity and efficiency.…”