Enhanced Cyclability of Lithium–Oxygen Batteries with Electrodes Protected by Surface Films Induced via In Situ Electrochemical Process

摘要

Although the rechargeable lithium-oxygen (Li-O-2) batteries have extremely high theoretical specific energy, the practical application of these batteries is still limited by the instability of their carbon-based air-electrode, Li metal anode, and electrodes, toward reduced oxygen species. Here a simple one-step in situ electrochemical precharging strategy is demonstrated to generate thin protective films on both carbon nanotubes (CNTs), air-electrodes and Li metal anodes simultaneously under an inert atmosphere. Li-O-2 cells after such pretreatment demonstrate significantly extended cycle life of 110 and 180 cycles under the capacity-limited protocol of 1000 mA h g(-1) and 500 mA h g(-1), respectively, which is far more than those without pretreatment. The thin-films formed from decomposition of electrolyte during in situ electrochemical precharging processes in an inert environment, can protect both CNTs air-electrode and Li metal anode prior to conventional Li-O-2 discharge/charge cycling, where reactive reduced oxygen species are formed. This work provides a new approach for protection of carbon-based air-electrodes and Li metal anodes in practical Li-O-2 batteries, and may also be applied to other battery systems.