In Situ Polymerized Polydopamine Nanoparticles as Enhanced Polymer Composite Electrolyte for All‐Solid‐State Lithium‐Ion Batteries

Abstract Polyethylene oxide (PEO) is considered to be an important polymer matrix for solid polymer electrolytes, owing to its excellent lithium salt solubility and low cost, but PEO suffers from many disadvantages such as low ion conductivity at room temperature, poor mechanical property, and flammability. This paper presents the fabrication of a novel composite electrolyte composed of polydopamine (PDA) nanoparticles and PEO through a facile in situ polymerization method. The PDA nanoparticles homogeneously disperse in the PEO matrix and substantially suppress the crystallization of PEO, thus significantly improving the ionic conductivity of PEO electrolyte. Meanwhile, tensile test, thermogravimetric analysis, and cone calorimeter characterizations demonstrate the improved mechanical properties, thermal stability, and flame resistance of the PEO electrolyte. In addition, the PDA/PEO electrolyte shows an expanded electrochemical window, and the all‐solid‐state lithium battery assembled from PDA/PEO electrolyte exhibits better rate performance and cycling stability as compared to the battery made from neat PEO electrolyte. This work provides a simple strategy for safe and high‐performance all‐solid‐state lithium‐ion batteries.