Since its commercialization in 1991, Li-ion batteries became an indispensable power source in our daily life activities. We use them in our mobile phones, laptops, electric vehicles, and many more mobile applications. However, this great technology faces two main challenges. The first is the energy density, that the amount of energy we can store per battery cell is still limited. The second is the safety, as current batteries can easily catch fire and explode if they are overheated. Overcoming these two challenges can be addressed by replacing the highly flammable commercially used electrolytes by less-flammable or non-flammable ones. Such electrolytes need to be compatible with the lithium metal anode so that the energy density of the batteries can be increased. Several classes of elec...[ Read more ]

Since its commercialization in 1991, Li-ion batteries became an indispensable power source in our daily life activities. We use them in our mobile phones, laptops, electric vehicles, and many more mobile applications. However, this great technology faces two main challenges. The first is the energy density, that the amount of energy we can store per battery cell is still limited. The second is the safety, as current batteries can easily catch fire and explode if they are overheated. Overcoming these two challenges can be addressed by replacing the highly flammable commercially used electrolytes by less-flammable or non-flammable ones. Such electrolytes need to be compatible with the lithium metal anode so that the energy density of the batteries can be increased. Several classes of electrolytes have been proposed as potential alternatives to the commercial ones. In this thesis, we considered two classes, namely: inorganic ceramic solid-state electrolytes (SSE) and plastic-crystal (PC) quasi-solid electrolytes.

We first used atomistic simulations to investigate the potential of Li₂OHCl anti-perovskite SSE and two of its fluorinated variants for use in lithium metal batteries (LMB). We studied the phase stability, electrochemical stability, mechanical properties, and ionic conductivities of the three SSEs. We applied the insights we got from our simulations to experimentally enable an LMB based on succinonitrile (SN), a non-ionic PC electrolyte. We found that using low loadings of fluoroethylene carbonate can enable LMB based on SN (SN-LMB) for 1000 cycles at room temperature running at 1 C rate. We also found that the cycle life of SN-LMB depends on the type of commercial separator used. To understand the mechanisms responsible for the cycle life of SN-LMB, we performed a post-mortem analysis to the cycled batteries. In the last part of the thesis, we discuss the use of the distribution of relaxation times (DRT) method as a complementary technique to the post-mortem analysis. We framed the DRT problem in a Bayesian statistical framework that can give a more accurate DRT than those obtained by classical methods. The use of the DRT method may help the development of LMB based on alternative electrolytes.