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An Experimental and Theoretical Study of the Mass Transport in Lithium-Ion Battery Electrolytes

Technical Report:

Abstract

Lithium-ion batteries are particularly suitable as energy storage solutions in high power applications, such as hybrid electric vehicles. It is generally considered that one of the processes that limit the power density for lithium-ion batteries is the mass transport in the electrolyte. Yet, it is still difficult to find a set of properties that fully describe the mass transport for the most common electrolytes. In this work, characterization studies of the mass transport were undertaken for two technically important lithium-ion battery electrolytes: (1) a liquid electrolyte which consist of LiPF6 dissolved in ethyl methyl carbonate (EMC) and ethylene carbonate (EC) and, (2) a gel electrolyte which consists of LiPF6 dissolved in ethylene carbonate, propylene carbonate (PC) and poly(vinylidenefluoride-hexafluoropropylene) (P(VdFHFP)).The mass transport in the electrolytes was characterized by combining several experiments. The Maxwell-Stefan equation was used as basis for the characterization. Models of the transport were formulated from the equation and the apparent transport properties were identified. The characterization methods were first analyzed mathematically in order to establish at which conditions the characterization experiments should be performed. The values of the apparent transport properties were then obtained by optimizing the models to the experimental responses. In order to give the characterization  More>>
Authors:
Publication Date:
Jul 01, 2011
Product Type:
Technical Report
Report Number:
TRITA-CHE-2011-6
Resource Relation:
Other Information: Thesis or Dissertation; TH: Doctoral thesis (TeknD); 49 refs., figs, tabs.
Subject:
25 ENERGY STORAGE; ELECTROLYTES; LITHIUM; ELECTRIC BATTERIES; HYBRID ELECTRIC-POWERED VEHICLES; SIMULATION; MATHEMATICS
OSTI ID:
1010815
Research Organizations:
KTH Royal Inst. of Technology, Stockholm (Sweden). School of Chemical Science and Engineering, Chemical Engineering and Technology, Applied Electrochemistry
Country of Origin:
Sweden
Language:
English
Other Identifying Numbers:
Other: ISBN 978-91-7415-852-6; ISSN 1654-1081; TRN: SE1107082
Availability:
Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-29121
Submitting Site:
SWD
Size:
64 p. pages
Announcement Date:
Apr 11, 2011

Technical Report:

Citation Formats

Nyman, Andreas. An Experimental and Theoretical Study of the Mass Transport in Lithium-Ion Battery Electrolytes. Sweden: N. p., 2011. Web.
Nyman, Andreas. An Experimental and Theoretical Study of the Mass Transport in Lithium-Ion Battery Electrolytes. Sweden.
Nyman, Andreas. 2011. "An Experimental and Theoretical Study of the Mass Transport in Lithium-Ion Battery Electrolytes." Sweden.
@misc{etde_1010815,
title = {An Experimental and Theoretical Study of the Mass Transport in Lithium-Ion Battery Electrolytes}
author = {Nyman, Andreas}
abstractNote = {Lithium-ion batteries are particularly suitable as energy storage solutions in high power applications, such as hybrid electric vehicles. It is generally considered that one of the processes that limit the power density for lithium-ion batteries is the mass transport in the electrolyte. Yet, it is still difficult to find a set of properties that fully describe the mass transport for the most common electrolytes. In this work, characterization studies of the mass transport were undertaken for two technically important lithium-ion battery electrolytes: (1) a liquid electrolyte which consist of LiPF6 dissolved in ethyl methyl carbonate (EMC) and ethylene carbonate (EC) and, (2) a gel electrolyte which consists of LiPF6 dissolved in ethylene carbonate, propylene carbonate (PC) and poly(vinylidenefluoride-hexafluoropropylene) (P(VdFHFP)).The mass transport in the electrolytes was characterized by combining several experiments. The Maxwell-Stefan equation was used as basis for the characterization. Models of the transport were formulated from the equation and the apparent transport properties were identified. The characterization methods were first analyzed mathematically in order to establish at which conditions the characterization experiments should be performed. The values of the apparent transport properties were then obtained by optimizing the models to the experimental responses. In order to give the characterization results a comprehensible interpretation and to allow benchmarking of electrolytes, the concept of a normalized potential gradient was introduced.The characterization results of the liquid electrolyte were used in a full cell model of a LiNi0.8Co0.15Al0.05O2 | LiPF6 EC:EMC (3:7) | MAG-10 cell. The model was developed to analyze the mass transport during a hybrid pulse power characterization (HPPC) test. The analysis was made with a method where the polarization was split up into parts each associated with a process within the cell. The optimum composition in terms of mass transport was found to lie between 0.5 and 1.2 mol/dm3 LiPF6 for the liquid electrolyte and between 5 and 7 wt. % LiPF6 for the gel electrolyte. Less amount of polymer in the gel electrolyte gave a faster mass transport. It was also found that the mass transport in the liquid electrolyte contributed to a major part of the polarization during HPPC tests}
place = {Sweden}
year = {2011}
month = {Jul}
}