Solid polymer nanocomposite electrolytes based on poly(ε‐caprolactone)‐based waterborne polyurethane–polyethylene oxide and fluorine‐doped carbon quantum dot‐MXene

Abstract The need for higher energy storage capability has encouraged researchers to move toward lithium‐metal batteries (LMBs). Due to the safety issue associated with liquid electrolytes, solid polymer electrolytes (SPEs) the main focus on polyethylene oxide (PEO) were at the center of the research. However, high crystallization, fast decomposition, and low thermomechanical stability has limited its application. Low lithium‐ion transference number () is another issue leading to polarization of the SPEs and consequently, triggering dendrite nucleation and growth. Here, we developed a series of SPEs based on PEO‐waterborne polyurethane (WPU) and nanoparticles of fluorine‐doped carbon quantum dot (fCQD) and MXene. The host polymer matrix was a blend of poly(ε‐caprolactone) (PCL)‐based WPU and PEO. The use of WPU and the nanoparticles increased the thermomechanical stability and suppressed PEO crystallinity through disrupting the spherulites growth and reducing the thermal stability of the crystallites. Using the WPU led to significant increase in () compared with previous reports. The prepared SPEs showed high‐electrochemical stability and ionic conductivity at and based on the results of cycling performance, a discharge capacity of 120.58 mAh/g and coulombic efficiency of 99.1% was achieved after 200 cycles.