Designing Stable Electrode Interfaces from a Pyrrolidine-Based Electrolyte for Improving LiNi_0.8Co_0.1Mn_0.1O₂ Batteries

Abstract

LiNi 0.8 Co 0.1 Mn 0.1 O 2 (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 (PYR 1(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 % PYR 1(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||LiNi 0.8 Co 0.1 Mn 0.1 O 2 cells was 107 mA h g −1 at 1 C.

Nanocomposite Polymer Gel Electrolyte Based on TiO2 Nanoparticles for Lithium Batteries

“…High-resolution spectra for 1 H, 7 Li, 11 B, 13 C, and 19 F were recorded on a Bruker Avance III 500 MHz NMR spectrometer. The measurements at frequencies of 500, 194, 160, 126, and 471 MHz for 1 H, 7 Li, 11 B, 13 C, and 19 F, respectively, were carried out at room temperature (22 ± 1 • C). The chemical shift scale was calibrated with the DMSO-d6 signal in the capillary as an external standard (2.50 ppm for 1 H).…”

“…No signal accumulation was applied. In order to obtain the 13 C NMR spectra, a standard sequence from the TopSpin (Bruker, Rheinstetten, Germany) zgpg30 library was used. The sequence is an accumulation of signals from 30 • pulses with the suppression of the 1 H spin-spin interaction for the duration of all the experimental times.…”

“…The 1 H and 13 C NMR spectra of the NPE2 and NPE6 compositions compared with the initial ionic liquid EMIBF 4 were recorded. The 1 H and 13 C NMR spectra are shown in Figures 5 and 6, respectively. The 1 H and 13 C NMR spectra are identical for both NPE compositions.…”

“…ILs have unique physicochemical properties: thermal stability, insignificant volatility, low combustibility, and high ionic conductivity [ 5 , 6 , 7 , 8 , 9 ]. Owing to these properties, they have found use as components of electrolytes for various electrochemical devices, supercapacitors, and lithium–ion batteries [ 10 , 11 , 12 , 13 , 14 ].…”

“…When polymer matrices are plasticised with ionic liquids, their thermal and mechanical properties are also improved [ 15 , 16 ]. However, when introducing ILs into lithium-conducting polymer electrolytes, the competitive transport of different ions occurs, and very low transport numbers for Li + cations are realised [ 13 , 14 , 16 ]. It is possible to increase the transfer numbers of target ions and to improve the electrochemical properties of the gel system by introducing ceramic nanofillers (for example, Al 2 O 3 , SiO 2 , ZrO 2 , TiO 2 , SnO 2 , etc.)…”