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.