Electronic Supplementary Information

A bifunctional electrolyte additive for H2O/HF

scavenging and enhanced

graphite/LiNi0.5Co0.2Mn0.3O2 cell performance at a

high voltage

Rong Zhou,a Jianxing Huang,a Shaobo Lai,a Jiyang Li,a Feng Wang,a Zhiqiang Chen,a

Weiqing Lin,a Chao Li,a Jing Wang*a and Jinbao Zhao*a

a. State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative

Innovation Center of Chemistry for Energy Materials, College of Chemistry

and Chemical Engineering, Xiamen University, Xiamen 361005, China

E-mail: jbzhao@xmu.edu.cn, wangjing2015@xmu.edu.cn

Keywords: Electrolyte additive, N,N-diethylamino trimethylsilane, High voltage,

LiNi0.5Co0.2Mn0.3O2, H2O/HF scavenger, Lithium-ion batteries

Electronic Supplementary Material (ESI) for Sustainable Energy & Fuels.This journal is © The Royal Society of Chemistry 2018

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Fig. S1 DFT-calculated reaction energies (kcal mol-1) for the self-decomposition of

neutral DEATMS to homolytic (Path 1) and heterolytic (Path 2) bond cleavage.

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Fig. S2 31P NMR spectrum of the baseline electrolyte with 2000 ppm H2O stored at 55

°C for 6 days. The degradation products are OPF2OR (triplet, -15.9 ppm, 1JP-F = 945.8

Hz) and multiple OPF(OR)2 type compounds (doublets, -7.3 ppm, 1JP-F = 936.7 Hz; -

7.5 ppm, 1JP-F = 921.1 Hz).

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Fig. S3 Linear sweep voltammograms of electrolytes with and without 0.5% DEATMS

from OCV to 6 V vs. Li/Li+ at a scan rate of 0.1 mV s-1.

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Fig. S4 Cycling voltammograms of Li/graphite half cells with and without 0.5%

DEATMS from OCV to 0 V vs. Li/Li+ at a scan rate of 0.1 mV s-1.

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Fig. S5 Cycling performances of (a) Li/NCM523 cells in a voltage range of 3.0 ~ 4.5

V at 1 C rate (1C = 160 mA g-1) and (b) Li/graphite cells in a voltage range of 0 ~ 3.0

V at 0.2 C rate (1C = 370 mA g-1) with and without DEATMS.

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Fig. S6 XPS profiles of the surface elements on the NCM523 cathode after pre-cycling

at a high voltage with and without the DEATMS additive.

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Fig. S7 Coulombic efficiency of graphite/NCM523 cells with and without 0.5 wt.%

DEATMS operated at 25 in different voltage ranges between (a) 3.0 ~ 4.3 V and (b) °C

3.0 ~ 4.5 V.

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Fig. S8 Normalized Raman spectra of the cathodes in the pristine state and after cycling

between 3.0 ~ 4.5 V.

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Fig. S9 SEM images of the (a) fresh graphite anode and (b) high-voltage cycled graphite

anodes with the baseline electrolyte and (c) 0.5% DEATMS electrolyte.

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Fig. S10 XPS profiles of the surface elements on the graphite anode after 100 cycles at

a high voltage with and without the DEATMS additive.

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Fig. S11 Coulombic efficiency of graphite/NCM523 cells with and without 0.5 wt.%

DEATMS cycled between 3.0 ~ 4.3 V at 55 .°C