Molecular Engineering of Network Solid Polymer Electrolytes for Enhanced Mechanical, Electrochemical and Ionic Transport Properties

Solid polymer electrolytes (SPEs) are regarded as a promising direction for the actualization of high energy density lithium metal batteries (LMBs). Currently, however, maintaining sufficient ionic conductivity, adequate electrochemical stability and optimum mechanical properties remains a significant challenge. In this work, we display how changes in molecular architecture and chemistry can tune such properties for optimal performance in LMBs. We synthesize and characterized a series of PEO-based comb-chain crosslinked network SPEs (conSPE) that utilize a macromolecular crosslinker. Functionalized inorganic nanoparticles can also be introduced into the network serve as an additional crosslinking point and improve SPE modulus. The comb-chain molecular architecture design allows for the optimization of mechanical and transport properties through the widely tunable network mesh size. The chemical makeup of the polymer network is shown to play a crucial role in achieving high electrochemical stability and stable solid electrolyte interphase formation (SEI). The combination of stable SEI formation and high mechanical toughness of the conSPE enables excellent cycling performance at elevated current densities. The conSPE platform provides a promising route for future design of high-performance electrolytes for LMBs.