Solid Polymer Electrolytes Based on Functionalized Tannic Acids from Natural Resources for All-Solid-State Lithium-Ion Batteries

Solid polymer electrolytes (SPEs) for all-solid-state lithium-ion batteries are prepared by simple one-pot polymerization induced by ultraviolet (UV) light using poly(ethylene glycol) methyl ether methacrylate (PEGMA) as an ion-conducting monomeric unit and tannic acid (TA)-based crosslinking agent and plasticizer. The crosslinking agent and plasticizer based on natural resources are obtained from the reaction of TA with glycidyl methacrylate and glycidyl poly(ethylene glycol), respectively. Dimensionally stable free-standing SPE having a large ionic conductivity of 5.6×10^-4 S cm^-1 at room temperature can be obtained by the polymerization of PEGMA into P(PEGMA) with a very small amount (0.1 wt%) of the crosslinking agent and 2.0 wt% of the plasticizer. The ionic conductivity value of SPE with a crosslinked structure is one order of magnitude larger than that of linear P(PEGMA) in the waxy state. Bring the tannic acid out! Renewable and natural tannic acid is modified to obtain a crosslinking agent and a plasticizer for solid polymer electrolytes (SPEs) of all-solid-state lithium-ion batteries. Larger capacity retentions can be obtained at high temperatures, without any safety problems. The unique features of these SPEs suggest that cheap and abundant natural resources can be utilized for energy storage applications.