Molecular dynamics simulations of separator-cathode interfacial thermal transport in a Li-ion cell

Abstract

While Li-ion cells show outstanding electrochemical performance, their poor thermal transport characteristics result in reduced performance as well as significant safety concerns. The heterogeneous interface between cathode and separator plays a vital role in the process of thermal conduction in a Li-ion cell. Recent experiments have shown that the cathode-separator interfacial thermal resistance contributes significantly to total thermal resistance within the cell. In this paper, thermal conductance across the cathode-separator interface is calculated using molecular dynamics (MD) simulations with IFF-CVFF force field. Thermal transport in a pristine heterogeneous interface as well as when bridged with 3-Aminopropyl triethoxysilane (APTES), n-Butyl trimethoxysilane (nBTMS) and 3-Mercaptopropyl trimethoxysilane (MPTMS) molecules is computed. It is shown that molecular bridging at the interface results in up to 250% improvement in interfacial thermal conductance for the APTES case, which is consistent with recent experimental data. These results quantify the key role of the cathode-separator interface in thermal transport within the Li-ion cell, as well as the potential improvement in interfacial thermal transport by molecular bridging. The techniques and results discussed here may help downselect molecular species for interfacial thermal transport enhancement in Li-ion cells.