Towards High Energy Density Aging Resistant Li-ion Polymer Batteries

A wide interest is mounting towards polymer electrolytes, due to their application in energy efficient rechargeable batteries, photo-electrochemical cells, electrochromics, and supercapacitors. Polymer electrolytes exhibit unique advantages such as mechanical integrity, wide variety of fabrication methods in desirable size and shape, possibility to fabricate an intimate electrode/electrolyte interface and adapt to a lightweight, leak-proof construction, and economic packaging structure. In this communication, we offer a summary of our results regarding 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 ion conducting (σ > 10–4 S cm–1 at 20 °C), electrochemically stable (> 5 V vs. Li), self-standing, robust and tack-free SPEs are successfully prepared via a rapid and easily up-scalable process including a light and/or thermally induced polymerization step. The resulting crosslinking allows the incorporation of high amounts of plasticisers (e.g., RTILs) and lithium salt (based on TFSI– anion), leading to a material with remarkable morphological characteristics in terms of homogeneity and mechanical abusability under highly stressful conditions. Lab-scale Li-polymer cells assembled 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.