Improved Parameterization of an Ethylene Carbonate Molecular Dynamics Model in Li-Air Batteries for Accurate Density and Transition Temperatures
Li-ion battery technology has reached a point in which the energy density can only be increased incrementally and will not meet the needs of future electric vehicles, portable power and military applications. Metal/air batteries have the potential to yield much higher energy density due to the elimination of the cathode to make a lighter battery package and the unlimited availability of oxygen from the environment. In particular, lithium-air batteries are especially attractive due to a high theoretical energy density. However, there are numerous challenges that must be solved before these batteries can be used commercially. In particular, the performance of the battery is highly dependent on the transport of lithium through the electrolyte.
Here, we investigate the effect of carbonate-based electrolyte chemistries on the lithium diffusion coefficient by molecular dynamics (MD) simulations and electrochemical cyclic voltammetry (CV) measurements. Typically, CV measurements have been shown to greatly underestimate the diffusion coefficient (see figure) for the Li-air battery by three orders of magnitude.
We will present a new method to utilize CV measurements to accurately predict lithium diffusion coefficients in Li-air batteries and also propose a new porous silica cathode material to maximize the diffusion of lithium and lithium oxide reaction products for maximum battery efficiency. The improved diffusion of these species is supported by modeling results.
Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000