Polymer electrolytes for durable lithium batteries operating in a wide temperature range

Polymer electrolytes exhibit unique advantages such as mechanical integrity, intimate electrode/electrolyte interface, possibility to be fabricated in desirable size and shape and adapted to a lightweight, leak-proof construction, and economic packaging structure. Here we offer a summary of our recent results on the synthesis, physico-chemical and electrochemical characterization of solid polymer electrolytes (SPEs) based on different monomers/oligomers (methacrylic and/or ethylene oxide based) with specific amounts of lithium salt, plasticizers and/or fillers. Profoundly ionic conducting (σ > 10–4 S cm–1 at 20 °C), electrochemically stable (> 5 V vs. Li), self-standing, tack-free SPEs are successfully prepared via a rapid and easily up-scalable process including a light induced polymerization step. Crosslinking allows the incorporation of high amounts of plasticisers (e.g., RTILs) and lithium salt (based on TFSI– anion), leading to materials with remarkable characteristics in terms of homogeneity and mechanical robustness under highly stressful conditions. Lab-scale Li-polymer cells show stable charge/discharge characteristics without any capacity fading at C/5 current regime (> 130 mAh g–1 in LiFePO4/Li configuration and > 150 mAh g–1 in TiO2/Li configuration even @ 20 °C). The overall performance of the SPEs postulates the possibility of effective implementation in the next generation of safe, durable and high energy density secondary all-solid Li-ion polymer batteries working at ambient and/or sub-ambient temperatures.