Electrolyte Modulators towards Polarization Immune Lithium-Ion Batteries for Sustainable Electric Transportation

1Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, California, 90095, United States. 2Education Ministry Key Lab of Resource Chemistry and Shanghai Key Laboratory of Rare Earth Functional Materials, Department of Chemistry, Shanghai Normal University, Shanghai 200234, P. R. China. 3School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, P. R. China. 4Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, California, 90095, United States. 5Chemistry Division, Brookhaven National Laboratory, Upton, NY 11973, United States. *Corresponding author. Email: lishen@ucla.edu, luucla@ucla.edu


Material Characterization
The crystal structure of UMCM-309a was characterized by x-ray diffraction with a Rigaku powder X-ray diffractometer (XRD) using Kα radiation (λ = 1.54 Å). The morphology was observed by field scanning electron microscopy (Nova 230 Nano SEM) and transmission electron microscopy (FEI T12 Quick CryoEM and CryoET TEM). N2 adsorption/desorption measurements were conducted by using a Micromeritics ASAP 2020 system at 77 K. Prior to S2 the measurement, a pristine UMCM-309a sample was degassed at 180 °C for 12 h. The Brunauer-Emmett-Teller (BET) method was employed to determine the specific surface area, and the Density functional theory (DFT) model was applied to calculate pore diameter. The morphology of a UMCM-309a nanosheet was characterized by atomic force microscopy (AFM) (AFM5200S; Hitachi High-Technologies Corporation). The sample was prepared by exfoliating the nanosheets, which were deposited on Si wafers. The Young's modulus of the electrolyte interface was measured by a scanning probe microscope (SPM-9700HT, Shimadzu Corp) using a silicon tip OMCL-AC240TS (resonance frequency = 70 kHz and force constant =2 N m −1 ). 19 F NMR and 7 Li NMR spectra were obtained from a Bruker DMX500 (500 MHz) spectrometer. All 19 F NMR and 7 Li NMR samples were prepared by completely digesting 50 μL LFS with 0.2 wt.% MEM and LFS samples in 500 μL of deuterium oxide (D2O). XAS was performed at beamline 7-BM of the National Synchrotron Light Source II at Brookhaven National Laboratory. Zr K-edge XAS spectra were collected in transmission mode. The XAS data were processed using Athena and Artemis software packages. Inductively coupled plasma (ICP) optical emission spectroscopy was conducted using a Shimadzu ICP-9000.
Thermogravimetric analysis (TGA) was carried out in argon atmosphere by a ramping rate of 10 °C min −1 . Raman spectroscopy was conducted on a Renishaw 2000 System with a He/Ne laser at a wavelength of 633 nm. The zeta potential was measured using a Malvern Zetasizer ZS. X-ray photoelectron spectroscopy (XPS) measurements were performed on an AXIS Ultra DLD instrument. The samples were prepared in a glovebox before quickly being transferred to a high-vacuum chamber.

Supplementary Figures and Tables
Supplementary Figure 1. Schematic illustration of thermal activation process of UMCM-309a that generates OMSs. Compared with the pristine sample, the activated UMCM-309a exhibits decreased surface area/pore volume (315 m 2 g −1 /0.5 cm 3 g −1 vs 831 m 2 g −1 and 0.9 cm 3 g −1 ), in addition to increased micropore size (8.6/13.7 Å vs 6.8/13.6 Å), which originates from shrinkage of the nanosheets and expanded interlayer spacing due to removal of the hydroxyl groups, respectively.     In order to draw further insights by relating electrolyte parameters to electrochemical performance, simulations were employed to model the cells measured in the lab using COMSOL software. The effect of several key properties on electrochemical performance, including the ionic conductivity ( ! ) and lithium transference (or transport) number ( "# ! ), were investigated. There are five dependent variables for this system, the electrolyte potential,  that can be added to the existing reaction sources, which is not necessary in this model.

COMSOL Simulations
Equations 1 through 5 are also used for the electrolyte in the separator, but with ! = 0.
In the solid electrode particles, the current density, $ [C m ). s )-], is defined by Equation   6, where σ $ [S m )-] is the effective electrical conductivity.
The total current density,

Constant Parameters
The parameters used in the LiFePO4 half-cell COMSOL simulation are shown in Supplementary Table 3

Simulation Results
Supplementary Figure 22. Discharge profiles of conceptual LiFePO4|Li cells at C rates of 1, 10, 20, and 50.