An organic additive assisting with high ionic conduction and dendrite resistance of polymer electrolytes

High-performance polymer electrolytes are desirable for developing solid-state lithium (Li) metal batteries (SSLMBs) with enhanced safety and high energy density; however, their applications are hindered by low ionic conductivity and uncontrolled Li-dendrite growth. Here, a poly(vinylidene fluoride) (PVDF)-based polymer electrolyte with an organic additive, 2-acrylamido-2-methylpropane sulfonic acid (AMPS), is synthesized. First, AMPS improves the Li + conduction by reducing the crystallinity of PVDF and immobilizing the anions. Second, AMPS assists with the formation of a LiF/Li 2 S x /Li 2 SO 3 /Li 3 N-rich interface between Li metal and the AMPS-PVDF polymer electrolyte (AP-PE), which effectively suppresses the growth of Li dendrites. Consequently, the AP-PE with a thickness of ∼28 μm shows a high ionic conductivity of 2.2 × 10 −4 S cm −1 at 26 °C, corresponding to an ultrahigh areal conductance of 78.6 mS cm −2 . Meanwhile, the AP-PE shows a large Li + transference number of ∼0.49, good electrochemical stability against a Li metal anode, and improved cycling stability in LiFePO 4 - and LiCoO 2 -based SSLMBs. 2-Acrylamido-2-methylpropane sulfonic acid (AMPS) is used as an organic additive for poly(vinylidene fluoride) (PVDF)-based polymer electrolytes to assist with the fast Li-ion conduction and formation of a stable interface.