Stable Solid Electrolyte Interphase Layer Formed by Electrochemical Pretreatment of Gel Polymer Coating on Li Metal Anode for Lithium–Oxygen Batteries

Lithium–oxygen (Li–O2) batteries exhibit the highest theoretical specific energy density among candidates for next-generation energy storage systems, but the instabilities of Li metal anode (LMA), air electrode, and electrolyte largely limit the practical applications of these batteries. Herein, we report an effective method to protect the LMA against side reactions between the LMA and the crossover contaminants such as highly reactive oxygen moieties. A solid electrolyte interphase (SEI) layer rich in inorganic components is formed on the LMA coated with poly(ethylene oxide) thin film through an in situ electrochemical precharging step under oxygen atmosphere. This uniformly distributed SEI layer interacts with the flexible polymer matrix and forms a submicrometer-sized gel-like polymer layer. This polymer-supported SEI layer leads to much longer cycle life (130 vs 65 cycles) as compared to that of pristine cells under the same testing conditions. It is also very effective to stabilize the LMA/electrolyte interphase with a redox mediator.