Single-ion conducting polymer electrolyte: A promising electrolyte formulation to extend the lifespans of LMBs

Lithium metal batteries (LMBs) are considered as "Holy Grail" energy storage and conversion devices in order to meet the continuous energy consumption demands, owing to their high energy density and specific energy. However, the persistent loss of cell capacity and power density caused by the non-uniform deposition of Li-ions on the anode surface, raises questions regarding the lifespan of these devices. Thus, upholding long-term cycling life of LMBs is the foremost attention of researchers in current time. By keeping this in mind, here, we first rewind one of the key factors that affect the lifespan of LMBs, i.e. the effect of formation and growth of Li-dendrites at anode with other undesirable side reactions. Moreover, an insight into the fresh research avenues for extending lifespans of LMBs such as designing of single-ion conducting polymer electrolytes (SIPEs) in various forms and methods are briefly reviewed. Additionally, the structure-property relationship of SIPEs made from conventional as well as emerging materials such as poly ionic liquids (PILs) and covalent organic frameworks (COFs) are also deliberated. The effect of various factors such as architecture, length, concentration, molecular weight, backbone polarity of SIPEs on Li-transference number (LTN) and ionic conductivity are extensively analysed. Finally, different future perspectives to modify the SIPEs has been proposed to realise increasing lifespan of LMBs. This article offers a cutting-edge knowledge to re-evaluate the major degradation issues in LMBs and introduces research on SIPEs as a robust avenue for advancements in battery sector.