A systematic study of some promising electrolyte additives
in Li[Ni
1/3
Mn
1/3
Co
1/3
]O
2
/graphite, Li[Ni
0.5
Mn
0.3
Co
0.2
]/graphite
and Li[Ni
0.6
Mn
0.2
Co
0.2
]/graphite pouch cells
Lin Ma
a
, Julian Self
a
, Mengyun Nie
a
, Stephen Glazier
a
, David Yaohui Wang
b
,
Yong-Shou Lin
b
, J.R. Dahn
a, *
a
Department of Physics and Atmospheric Science, Dalhousie University, Halifax, B3H 3J5, Canada
b
Research Institute, Amperex Technology Limited, Ningde, Fujian, 352100, China
highlights
Advanced additives were compared to vinylene carbonate in NMC111, NMC532 and NMC622 cells.
At 4.2 V, all advanced additives performed well with all positive electrode materials.
At 4.4 V, NMC622 shows more gas production than the other materials with all additives.
article info
Article history:
Received 23 July 2015
Received in revised form
19 August 2015
Accepted 23 August 2015
Available online xxx
Keywords:
Lithium ion cells
Electrolyte additives
Systematic comparison
NMC/Graphite pouch cells
abstract
Li[Ni
1/3
Mn
1/3
Co
1/3
]O
2
/graphite, Li[Ni
0.5
Mn
0.3
Co
0.2
]O
2
/graphite and Li[Ni
0.6
Mn
0.2
Co
0.2
O
2
]/graphite pouch
cells were examined with and without electrolyte additives using the ultra high precision charger at
Dalhousie University, electrochemical impedance spectroscopy, gas evolution measurements and “cycle-
store” tests. The electrolyte additives tested were vinylene carbonate (VC), prop-1-ene-1,3-sultone (PES),
pyridine-boron trifluoride (PBF), 2% PES þ 1% methylene methanedisulfonate (MMDS) þ 1% tris(-
trimethylsilyl) phosphite (TTSPi) and 0.5% pyrazine di-boron trifluoride (PRZ) þ 1% MMDS. The charge
end-point capacity slippage, capacity fade, coulombic efficiency, impedance change during cycling, gas
evolution and voltage drop during “cycle-store” testing were compared to gain an understanding of the
effects of these promising electrolyte additives or additive combinations on the different types of pouch
cells. It is hoped that this report can be used as a guide or reference for the wise choice of electrolyte
additives in Li[Ni
1/3
Mn
1/3
Co
1/3
]O
2
/graphite, Li[Ni
0.5
Mn
0.3
Co
0.2
]O
2
/graphite and Li[Ni
0.6
Mn
0.2
Co
0.2
O
2
]/
graphite pouch cells and also to show the shortcomings of particular positive electrode compositions.
© 2015 Elsevier B.V. All rights reserved.
1. Introduction
Li-ion cells are widely used in numerous applications, from
portable electronics to electrified vehicles. In order to meet the
increasing demands of these applications, suitable electrode ma-
terials and electrolyte systems, which can lead to higher energy
density, higher power and longer cycle life, have been developed
during the past two decades [1e3].
Li[Ni
1/3
Mn
1/3
Co
1/3
]O
2
(NMC111) is a popular positive electrode
material because of its low cost, low toxicity and low reactivity with
electrolyte at elevated temperatures in the presence of suitable
additives [4]. Higher nickel content in NMC can increase specific
capacity to a particular cut-off potential, which improves energy
density to that cut-off potential. Li[Ni
0.5
Mn
0.3
Co
0.2
]O
2
(NMC532) [5]
is a widely used alternative to NMC111 and Li[Ni
0.6
Mn
0.2
Co
0.2
]O
2
(NMC622) [6,7] is considered to be a promising higher energy
density material.
In addition to the choice of electrode materials, electrolyte ad-
ditives can extend the lifetime and also increase the energy density
of cells by allowing high voltage operation. Some well-known
electrolyte additives such as vinylene carbonate (VC) and prop-1-
ene-1,3-sultone (PES), which can increase the lifetime of cells,
have been studied by many researchers. Aurbach et al. [8] showed
that VC can decrease the impedance of LiNiO
2
and LiMn
2
O
4
* Corresponding author.
E-mail address: jeff.dahn@dal.ca (J.R. Dahn).
Contents lists available at ScienceDirect
Journal of Power Sources
journal homepage: www.elsevier.com/locate/jpowsour
http://dx.doi.org/10.1016/j.jpowsour.2015.08.084
0378-7753/© 2015 Elsevier B.V. All rights reserved.
Journal of Power Sources 299 (2015) 130e138