To decrease carbon dioxide emissions, unprecedented efforts are being undertaken toward the development of efficient and inexpensive electric vehicles and stationary energy-storage systems. Lithium-ion batteries represent an efficient solution, that have transformed personal electronics and enabled the market introduction of electric vehicles. However, the ever-growing energy storage industry imposes great demands that current lithium-ion batteries could hardly satisfy. In this perspective, the use of metallic lithium as anode, both in Li-ion cells and in the so-called “post Li-ion technologies”, would represent the “holy grail” of battery research thanks to its extremely high theoretical specific capacity (3860 mA h g^-1), the lowest redox potential (-3.040 V vs the standard hydrogen electrode) and a low gravimetric density (0.534 g cm^-3).

However, metallic Li also presents many challenges derived primarily from dendrite formation upon cycling causing both safety issues and poor cycling performance. In addition, liquid electrolytes contain combustible organic solvents that can cause leakage and fire risks during overcharge or abused conditions, especially in large-scale operation. Therefore, replacement of liquid electrolytes with a solid electrolyte has been recognized as a fundamental approach to effectively address the above problems.

Among the solid-state systems under study, polymer-based electrolytes represent a good compromise in term of room temperature ionic conductivity, thermal and electrochemical stability, and above all, interfacial contact. In lithium metal batteries, the preparation of methacrylate-based polymer matrix, in a one pot, solvent free, UV or thermally induced, radical polymerization, is an inexpensive and quick method to obtain versatile membranes [1]. Meanwhile, eventual activation with small amount of ionic liquids can allow to obtain composite electrolytes with outstanding room-temperature conductivities, while preserving the non-flammability of the system thus enhancing the safety [2]. The simplicity of the formulation and the preparation method open the road to highly versatile electrolytes, adaptable in function of the final application [3]. Additionally, the insertion of particular groups in the matrix can introduce self-healing abilities (for example through dynamic hydrogen bonding), further improving the safety features of the cells [4]. Last but not least, bio-derived macromolecules can be functionalized with methacrylate groups to be then directly used as oligomers in the same kind of procedures, obtaining interesting quasi solid state electrolyte systems directly from waste [5, 6, 7], and fully integrating the final device in a circular economy approach.