Disparity among cyclic alkyl carbonates associated with the cathode–electrolyte interphase at high voltage

Abstract

Elevating cut-off voltage is an efficient approach to boost the energy density of Li-ion batteries. However, the failure of conventional carbonate-based electrolyte at high voltage necessitates fundamental understandings of the formation mechanism of the cathode–electrolyte interphase (CEI), especially the contribution from skeleton solvents. In the present work, density functional theory (DFT) calculations reveal the disparity in the productivity and oxidative stability of organic components in the CEI associated with ethylene carbonate (EC), propylene carbonate (PC) and fluoroethylene carbonate (FEC). These two indicators could jointly determine the existence of lithium alkyl carbonates in the CEI, suggested by the species with a m/z of 95 detected with time of flight secondary ion mass spectroscopy (TOF-SIMS). That disparity results in a prominent difference in the capacity retention at high voltage associated with EC, PC and FEC, respectively. These understandings of cyclic carbonates could shed light on bottom-up strategies in electrolyte engineering for the high-voltage electrolyte.