Improving Fast-Charging Performance of Lithium-Ion Batteries through Electrode-Electrolyte Interfacial Engineering

The solid-electrolyte interphase (SEI) is a key element in anode-electrolyte interactions and ultimately contributes to improving the lifespan and fast-charging capability of lithium-ion batteries. The conventional additive vinyl carbonate (VC) generates spatially dense and rigid poly VC species that may not ensure fast Li⁺ transport across the SEI on the anode. Here, a synthetic additive called isosorbide 2,5-dimethanesulfonate (ISDMS) with a polar oxygen-rich motif is reported that can competitively coordinate with Li⁺ ions and allow the entrance of PF₆ ^- anions into the core solvation structure. The existence of ISDMS and PF₆ ^- in the core solvation structure along with Li⁺ ions enables the movement of anions toward the anode during the first charge, leading to a significant contribution of ISDMS and LiPF₆ to SEI formation. ISDMS leads to the creation of ionically conductive and electrochemically stable SEI that can elevate the fast-charging performance and increase the lifespan of LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811)/graphite full cells. Additionally, a sulfur-rich cathode-electrolyte interface with a high stability under elevated-temperature and high-voltage conditions is constructed through the sacrificial oxidation of ISDMS, thus concomitantly improving the stability of the electrolyte and the NCM811 cathode in a full cell with a charge voltage cut-off of 4.4 V.