Room Temperature Solid-State Lithium Polymer Battery with Polyionic Liquid Pentablock Terpolymer Electrolyte

Abstract

Lithium ion batteries are currently the leading commercial technology for portable electronic devices and electric vehicles. However, new solid polymer electrolytes (SPEs) that comprehensively possess the preferred properties of high ion conductivity, high electrochemical stability, robust mechanical properties, flexibility, and good film forming properties, are required to improve the safety and lifetime of lithium ion batteries. Although diblock copolymers have been explored as SPEs and can potentially provide the orthogonal properties of high ion conduction and high mechanical strength simultaneously in a solid-state material, there are limitations to diblock copolymer-salt mixture systems, such as a limited set of morphologies, and a lack of means to achieve simultaneous combination of more than two properties ( e.g. , conductivity, strength, flexibility). Compared to diblock copolymers, multiblock polymers involve more than two polymer chemistries and therefore enable the possibility to conjoin many of the desired properties, such as high ion conductivity, mechanical strength, flexibility, good film forming properties, processability, and high electrochemical stability all into a single materials platform. In this study, a lithium ion conducting polyionic liquid pentablock terpolymer (PILPTP) was investigated as a solid polymer electrolyte (SPE) for lithium ion batteries.The morphology, chemical, thermal, mechanical, and electrochemical properties were examined as function of ionic liquid composition, cation chemistry, and film processing conditions. Coin cell Li 4 Ti 5 O 12 /SPE/LiCoO 2 batteries were fabricated with the lithium ion conducting PILPTP as the SPE and room temperature battery performance was demonstrated at high capacity and high cycle life. Overall, this work suggests, for the first time, that lithium conducting polyionic liquid multiblock polymers can be promising electrolyte candidates for developing safe and high performing room temperature solid-state lithium ion batteries.