High voltage lithium ion batteries have been a focus in the current energy storage research due to their potential application as high energy density batteries for electric vehicles. With more energy stored in a system with the same weight and volume, the impact of battery fabrication and its utilization on the environment will be minimized .Electrolyte solutions based on fluorinated solvents were studied in high-voltage Li-ion cells using lithium as the anode has a great enhancement over conventional electrolyte and Li1.2Mn0.56Co0.08Ni0.16O2 as the cathode provides excellent voltage stability on the 5.0 V at both ambient and elevated temperatures. Performance can be reach peak by replacing convectional alky carbonate solvents in electrolyte solution by fluorinated cosolvents. Fluorinated electrolyte solution act as a buffering surface film which is highly reactive electrophilic alkyl carbonates, from continuous detrimental reactions with solution species. Excellent cyclic performance was recorded in solution containing fluorinated solvents. The extraordinary electrochemical stability of this electrolyte solution makes it a suitable candidate for other high-voltage cathode materials.

1. TKM College of Engineering
Department of Chemical Engineering
CH451 Seminar and Project Preliminary
Extended Abstract
Electrolyte Solutions for Rechargeable Li-Ion Batteries Based on
Fluorinated Solvents
Submitted by Guide Seminar
Coordinator
Amal Thomas Prof. Anand Unni Prof. Al Ameen A
B17CHA66
August 2020
(Semester VII, August – December 2020, AY: 2020 – 2021)

2. 1
Electrolyte Solutions for Rechargeable Li-Ion Batteries Based on
Fluorinated Solvents
Abstract
High voltage lithium ion batteries have been a focus in the current energy storage research due to their
potential application as high energy density batteries for electric vehicles. With more energy stored in
a system with the same weight and volume, the impact of battery fabrication and its utilization on the
environment will be minimized .Electrolyte solutions based on fluorinated solvents were studied in
high-voltage Li-ion cells using lithium as the anode has a great enhancement over conventional
electrolyte and Li1.2Mn0.56Co0.08Ni0.16O2 as the cathode provides excellent voltage stability on the 5.0
V at both ambient and elevated temperatures. Performance can be reach peak by replacing convectional
alky carbonate solvents in electrolyte solution by fluorinated cosolvents. Fluorinated electrolyte
solution act as a buffering surface film which is highly reactive electrophilic alkyl carbonates, from
continuous detrimental reactions with solution species. Excellent cyclic performance was recorded in
solution containing fluorinated solvents. The extraordinary electrochemical stability of this electrolyte
solution makes it a suitable candidate for other high-voltage cathode materials.
Keywords
lithium-ion batteries (LIBs), electric vehicles (EVs), fluorinated alkyl carbonates (FEC),
tris(trimethylsilyl)phosphate (TMSP), Li1.2Mn0.56Co0.08Ni0.16O2/graphite cells.
Introduction
High-energy-density lithium-ion batteries (LIBs) have been the focus of extensive research and
development efforts throughout the world. Requirement for high voltage battery for electric vehicles
(EVs), development of high-voltage are expected to increase the energy and power density of LIBs.[2]
However high operation voltage creates challenges for the battery components, such as binder
instability, electrolyte decomposition, cathode structure degradation, metal dissolution from cathode,
metal deposition on anode and insufficient cycles, to mitigate these problems by using a electrolyte
solvent with high oxidation potential to form a surface layer [4].

3. 2
Literature review
The wide and successful use of LIBs as major power sources for mobile electronic devices has reached
a high level of self-confidence, which has pushed their use further to propel electric and hybrid EVs.
Using fluorinated alkyl carbonates (FEC) improves the rate capability and low temperature
performance of soft carbons and graphite electrodes. The high voltage cathode material
Li1.2Mn0.56Co0.08Ni0.16O2 belongs to family of Li- and Mn-rich NCM cathode material (Li, Mn, Ni, Co)
providing highest specific capacity relevant to lithiated transition metal [1].
Conventional electrolyte solutions based on alkyl carbonate solvents are highly susceptible to
decomposition at potentials above 4.3 V vs. Li/Li+. Hence, commonly used commercial electrolyte
solutions are not suitable for high voltage Li-ion cells. The substitution of fluorine atoms in the cyclic
carbonate profoundly enhances the stability of the lithium metal anode while fluoroalkyl and alkoxy
substituents are detrimental [3], to improve the electrochemical performance of high-energy
NCM(HE-NCM) numerous modification such as lattice doping, surface coating and reactive gas
treatments can be made.
Another important advantage of using fluorinated solvents in high-voltage Li cells relates to the unique
surface chemistry that both anodes and cathodes may develop in such solvents, which can lead to an
effective passivation of reactive electrodes. Zhang et al studied the stability of different electrolyte
solutions containing fluorinated solvent under high voltage conditions, and stating that the electrolytes
composed of fluorinated cyclic carbonate (F-AEC), fluorinated linear carbonate (F-EMC) and
fluorinated ether (F-EPE) have superior anodic stability compared with the EC/EMC-based Gen2
electrolyte. The electrochemical floating test shows that the substitution of EMC with F-EMC and EC
with F-AEC greatly improves the voltage limits of the electrolyte [5].
The stability of these electrolyte solution depends on various impurities, by the use of
tris(trimethylsilyl)phosphate (TMSP) additive prevents the dissolution of Ni and Mn from cathodes by
acting as acid scavengers, removing HF from electrolyte solutions. In addition, LiPO3 coating can
effectively act as a passivation layer to minimize electrolyte electrode interface side reactions and thus
improve the long-term cyclability. By introducing TMSP the cycling stability of high-voltage
Li1.2Mn0.56Co0.08Ni0.16O2 cathodes (charged up to 4.8 V) can be enhanced significantly [4].
Fluorinated solvents are advantageous for LIBs, as they can induce the formation of protecting films
on the electrode surfaces (both on the cathodes and the anodes) that lead to the passivation of the
electrodes. This cathode used here provide very high specific capacity due to redox activity of oxygen

4. 3
anions (which are highly basic and nucleophilic), the presence of surface films that avoid side reactions
between the oxygen species and the electrophilic alkyl carbonate solvents. The presence of fluorine
atoms in the solvent molecules enables the elimination of HF and the formation of double bonds by
reactions of fluorinated solvent molecules with basic electrode species. Excellent cycling performance
of such full cells was recorded (1000 cycles) with solutions containing 2FEC, fluorinated ether (F-
EPE), and 1% TMSP as an additive [1].
Objectives
Formulations of electrolyte solutions using fluorinated solvents and with suitable additive which
significantly improve the performance which include stability, safety and prolonged life of high
voltage Li-ion cells based on cathode Li1.2Mn0.56Co0.08Ni0.16O2 which can be used for batteries in
electromobility.
References
1. Ortal Lavi, Shalom Luski, Netanel Shpigel, Chen Menachem, Zvika Pomerantz, Yuval Elias,
and Doron Aurbach ,2020, “Electrolyte Solutions for Rechargeable Li-Ion Batteries Based on
Fluorinated Solvents,” ACS Appl. Energy Mater, 3, 7485−7499.
2. Zhonghua Lu,a, D. D. MacNeil,b, and J. R. Dahna,b, 2001, “Layered Cathode Materials
Li1.2Mn0.56Co0.08Ni0.16O2 for Lithium-Ion Batteries,” Electrochemical and Solid-State Letters,
4(11),A191-A194.
3. Su, C.-C. He, M.; Amine, R. Chen, Z. Sahore, R. Dietz Rago, N. Amine, K, 2019 “Cyclic
carbonate for highly stable cycling of high voltage lithium metal batteries.” Energy Storage
Mater, 17, 284−292.
4. Jin Chong, Jingping Zhang, Haiming Xie, Xiangyun Song, Gao Liu, Vincent Battaglia, Shidi
Xun and Rongsun Wang, 2016, “High performance LiNi0.5Mn1.5O4 cathode material with a
bifunctional coating for lithium ion batteries,” RSC Advances, DOI:10.1039/C6RA00119J.
5. Zhengcheng Zhang, Libo Hu, Huiming Wu, Wei Weng, Meiten Koh, Paul C. Redfern, Larry
A. Curtissb and Khalil Amine,2013, “Fluorinated electrolytes for 5 V lithium-ion battery
chemistry,” RSC Publishing, DOI: 10.1039/c3ee24414.