Metallic lithium is an ideal anode material for secondary batteries because it has the lowest electrochemical potential and the highest theoretical specific capacity. The high reactivity of metallic lithium and the formation of dendrites on repeated charging have so far prevented its use. With suitable protection it has the potential to become commercially viable in many different areas. A promising protective material is a cellulose-based composite material consisting of modified nanofibrillated cellulose and lithium nitrate that fills pores created by cellulose fibers. Using electrochemical impedance spectroscopy, we have found that lithium ion migration through the composite protective layer of cellulose follows the concept of solvent-in-salt electrolyte. We identified tetraethylene glycol dimethyl ether (TEGDME) as a suitable solvent. To show conductive properties, the mass of lithium nitrate in the cellulose protective layer had to be higher than the mass of TEGDME.
|
