The liquid electrolytes in lithium-air (oxygen) batteries are prone to volatilize, leak, flame, and cause uneven deposition of lithium during cycling, which makes the batteries to face serious problems in terms of safety and cycling stability. A novel Janus quasi-solid composite polymer electrolyte was fabricated by perfluorosulfonic acid (Nafion) membranes with tunable thickness and poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP). The Nafion membranes not only guarantee the mechanical strength of the composites but also effectively prevent the migration of certain anions and macromolecules. The results indicate that Janus quasi-solid composite polymer electrolytes have excellent thermal stability, high lithium-ion migration number, and wide electrochemical window. Lithium-oxygen batteries using the novel quasi-solid composite electrolytes perform lower polarization and better cycling stability. The excellent properties of the quasi-solid composite electrolytes make it one of the effective materials for improving the cycling stability of lithium-air (oxygen) batteries.
Keywords: cycling stability; lithium−oxygen battery; perfluorosulfonic acid; poly(vinylidene fluoride)-hexafluoropropylene; quasi-solid polymer electrolytes.