Stabilizing Li Anodes in I₂ Steam to Tackle the Shuttling-Induced Depletion of an Iodide/Triiodide Redox Mediator in Li–O₂ Batteries with Suppressed Li Dendrite Growth

Abstract

Redox mediators (RMs) have become a significant point in the now-established Li−O 2 battery system to reduce the charging overpotential in the oxygen evolution process. Nevertheless, a major inherent barrier of the RM is the redox shuttling between the Li metal anode and mobile RM, resulting in the corrosion of Li and depletion of RM. In this study, taking iodide/triiodide as a model RM, we propose an effective strategy by immersing the Li metal anode in I 2 steam to create a 1.5 μm thick surface protective layer. The resultant ionic conductive LiI layer on the Li metal anode can not only suppress Li dendrite growth but also act as a buffer layer between the RM and bare Li. By combining the iodide/triiodide RM with the LiI protective layer, the Li−O 2 battery shows low and steady charge voltage plateaus of ∼3.6 V over 70 cycles. Importantly, the symmetrical cell using the LiI-protected Li electrode exhibited small Li plating/stripping overpotentials (∼20 mV, 480 h), far superior to that of the bare Li electrode (∼70 mV, 300 h). The in situ interfacial observation shows that dendrite growth on the Li metal can be effectively suppressed by optimizing the LiI protective layer.

Systematic Study of O2 Supply in Li–O2 Batteries with High and Low Doner Number Solvents

“…3−5 Thus, it is extremely necessary to develop systems with higher energy density, such as Li−O 2 batteries, which have a theoretical energy density with respect to the anode (11700 Wh kg −1 ) comparable to gasoline (13000 Wh kg −1 ) and much higher than Li-ion batteries (400 Wh kg −1 ). 3,6,7 On the other hand, despite being a promising alternative, Li−O 2 batteries are still not technologically developed enough to reach high energy densities while maintaining high energy efficiency and long cycle life. The capacity and cycling performance of these batteries are dependent on many variables, such as stable Limetal anodes and electrolytes, air electrode materials, and limited current density.…”

“…Energy storage systems are becoming a viable alternative to replace fossil fuels in the transport system and in energy storage from intermittent sources such as solar and wind energies. , At present, Li-ion batteries occupy the most commonly used solution. However, these devices still fall short of the future demand for energy storage. − Thus, it is extremely necessary to develop systems with higher energy density, such as Li–O 2 batteries, which have a theoretical energy density with respect to the anode (11700 Wh kg –1 ) comparable to gasoline (13000 Wh kg –1 ) and much higher than Li-ion batteries (400 Wh kg –1 ). ,, On the other hand, despite being a promising alternative, Li–O 2 batteries are still not technologically developed enough to reach high energy densities while maintaining high energy efficiency and long cycle life. The capacity and cycling performance of these batteries are dependent on many variables, such as stable Li-metal anodes and electrolytes, air electrode materials, and limited current density. − Besides less reported, however fundamental, is the supply of air/O 2 to the device, acting on the performance and future commercial applications of this technology. , …”

Strategies toward anode stabilization in nonaqueous alkali metal–oxygen batteries

“…Besides, the SEI could also be formed via Li foil in selenium vapor 49 and I 2 steam. 50 The reaction between molten Li and other solid substances can also generate an SEI film. For example, molten lithium could react with polytetrafluoroethylene (PTFE).…”

A fluoroalkyl iodide additive for Li–O2 battery electrolytes enables stable cycle life and high reversibility

“…22 Z. Shao et al employed an I 2 stream to improve the stability of Li metal and achieved stable Li–O 2 battery operation for over 70 cycles under 1000 mA h g −1 . 23 H. Xie et al reported 2-dimethyl-3-propylimidazoleumiodide (DMPII) as a multifunctional redox mediator. It assists in the formation and decomposition of Li 2 O 2 , and also plays a role in generating a protective layer on the Li metal surface.…”