Hybrid polymer–liquid lithium ION electrolytes: Effect of carbon black during polymerization-induced phase separation

Abstract

An increasing demand for alternative electrolyte systems is emerging to address limitations associated with traditional liquid electrolytes in lithium-ion batteries (LIBs). Hybrid polymer-liquid electrolytes (HEs) combine the merits of solid polymers and liquid electrolytes in a heterogeneous phase-separated system where the polymer phase encapsulates the liquid ion-conducting phase. These electrolytes are synthesized through polymerization-induced phase separation (PIPS), resulting in the formation of a porous three-dimensional polymer network. Carbon black (CB) serves as conductive additive in LIBs electrodes, enhancing electric conductivity and thereby improving the battery performance and lifespan. How CB, already present in conventional electrodes, affects the PIPS process during the formation of HEs for LIBs, focusing on the material interactions and the formed microstructure properties, has been investigated. Addition of CB does not negatively affect the result of PIPS process, and it permits high conversion rate and compatibility with HE at all CB concentrations investigated. Morphological analysis in combination with nuclear magnetic resonance (NMR) and electrochemical impedance spectroscopy (EIS) reveals consistent macroporous and mesoporous structures, indicating the robustness of HEs to CB content variation. Understanding the interaction between CB and HEs during the manufacturing process and the impact of CB on the structural integrity and compatibility of the HE system, aids the integration of HEs with existing electrode materials in practical battery configurations.