Designing Stable Electrode Interfaces from a Pyrrolidine-Based Electrolyte for Improving LiNi0.8Co0.1Mn0.1O2 Batteries

LiNi0.8Co0.1Mn0.1O2 (NCM 811) has superior capacity but meanwhile also faces continuous electrolyte decomposition and transition metal dissolution induced by unstable cathode electrolyte interphase (CEI) films. The poor compatibility of the traditional electrolyte and lithium anode and the uncontrollable growth of the lithium (Li) dendrite also hinder the application of the lithium anode. Based on this, we designed the 1-methyl-1-cyanopropylpyrrolidine bisfluoromethanesulfonimide salt (PYR1(4CN)TFSI) to reduce the interface impedance on the cathode side and enhance the compatibility between the electrolytes and the lithium metal anode. A uniform and thin CEI was formed on the cathode side, and a dense and stable solid–electrolyte interphase was formed on the anode side, which effectively inhibited the side reaction and further promoted the electrochemical performance. The symmetrical cells with the addition of 0.5 wt % PYR1(4CN)TFSI can be maintained from 400 h to more than 750 h at a current density of 0.5 mA cm–2. After 200 cycles, the discharge specific capacity delivered by Li||LiNi0.8Co0.1Mn0.1O2 cells was 107 mA h g–1 at 1 C.