skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Characterization of Cathode Materials for Rechargeable Lithium Batteries using Synchrotron Based In Situ X-ray Techniques

Abstract

The emergence of portable telecommunication, computer equipment and ultimately hybrid electric vehicles has created a substantial interest in manufacturing rechargeable batteries that are less expensive, non-toxic, operate for longer time, small in size and weigh less. Li-ion batteries are taking an increasing share of the rechargeable battery market. The present commercial battery is based on a layered LiCoO{sub 2} cathode and a graphitized carbon anode. LiCoO{sub 2} is expensive but it has the advantage being easily manufactured in a reproducible manner. Other low cost layered compounds such as LiNiO{sub 2}, LiNi{sub 0.85}Co{sub 0.15}O{sub 2} or cubic spinels such as LiMn{sub 2}O{sub 4} have been considered. However, these suffer from cycle life and thermal stability problems. Recently, some battery companies have demonstrated a new concept of mixing two different types of insertion compounds to make a composite cathode, aimed at reducing cost and improving self-discharge. Reports clearly showed that this blending technique can prevent the decline in ·capacity caused by cycling or storage at elevated temperatures. However, not much work has been reported on the charge-discharge characteristics and phase transitions for these composite cathodes. Understanding the structure and structural changes of electrode materials during the electrochemical cycling is the key tomore » develop better .lithium ion batteries. The successful commercialization of the· lithium-ion battery is mainly built on the advances in solid state chemistry of the intercalation compounds. Most of the progress in understanding the lithium ion battery materials has been obtained from x-ray diffraction studies. Up to now, most XRD studies on lithium-ion battery materials have been done ex situ. Although these ex situ XRD studies have provided important information· about the structures of battery materials, they do face three major problems. First of all, the pre-selected charge (discharge) states may not be representative for the full picture of the structural changes during charge (discharge). In other words, the important information might be missed for those charge (discharge) states which were not selected for ex situ XRD studies. Secondly, the structure of the sample may have changed after removed from the cell. Finally, it is impossible to use the ex situ XRD to study the dynamic effects during high rate charge-discharge, which is crucial for the application of lithium-ion batteries for electric vehicle. A few in situ studies have been done using conventional x-ray tube sources. All of the in situ XRD studies using conventional x-ray tube sources have been done in the reflection mode in cells with beryllium windows. Because of the weak signals, data collection takes a long time, often several hundred hours for a single charge-discharge cycle. This long time data collection is not suitable for dynamic studies at all. Furthermore, in the reflection mode, the x-ray beam probes mainly the surface layer of the cathode materials. Iri collaboration with LG Chemical Ltd., BNL group designed and constructed the cells for in situ studies. LG Chemical provided several blended samples and pouch cells to BNL for preliminary in situ study. The LG Chemical provided help on integrate the blended cathode into these cells. The BNL team carried out in situ XAS and XRD studies on the samples and pouch cells provided by LG Chemical under normal charge-discharge conditions at elevated temperature.« less

Authors:
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
973810
Report Number(s):
BNL-91107-2007
C-06-02
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE

Citation Formats

Yang, Xiao-Qing. Characterization of Cathode Materials for Rechargeable Lithium Batteries using Synchrotron Based In Situ X-ray Techniques. United States: N. p., 2007. Web. doi:10.2172/973810.
Yang, Xiao-Qing. Characterization of Cathode Materials for Rechargeable Lithium Batteries using Synchrotron Based In Situ X-ray Techniques. United States. doi:10.2172/973810.
Yang, Xiao-Qing. Wed . "Characterization of Cathode Materials for Rechargeable Lithium Batteries using Synchrotron Based In Situ X-ray Techniques". United States. doi:10.2172/973810. https://www.osti.gov/servlets/purl/973810.
@article{osti_973810,
title = {Characterization of Cathode Materials for Rechargeable Lithium Batteries using Synchrotron Based In Situ X-ray Techniques},
author = {Yang, Xiao-Qing},
abstractNote = {The emergence of portable telecommunication, computer equipment and ultimately hybrid electric vehicles has created a substantial interest in manufacturing rechargeable batteries that are less expensive, non-toxic, operate for longer time, small in size and weigh less. Li-ion batteries are taking an increasing share of the rechargeable battery market. The present commercial battery is based on a layered LiCoO{sub 2} cathode and a graphitized carbon anode. LiCoO{sub 2} is expensive but it has the advantage being easily manufactured in a reproducible manner. Other low cost layered compounds such as LiNiO{sub 2}, LiNi{sub 0.85}Co{sub 0.15}O{sub 2} or cubic spinels such as LiMn{sub 2}O{sub 4} have been considered. However, these suffer from cycle life and thermal stability problems. Recently, some battery companies have demonstrated a new concept of mixing two different types of insertion compounds to make a composite cathode, aimed at reducing cost and improving self-discharge. Reports clearly showed that this blending technique can prevent the decline in ·capacity caused by cycling or storage at elevated temperatures. However, not much work has been reported on the charge-discharge characteristics and phase transitions for these composite cathodes. Understanding the structure and structural changes of electrode materials during the electrochemical cycling is the key to develop better .lithium ion batteries. The successful commercialization of the· lithium-ion battery is mainly built on the advances in solid state chemistry of the intercalation compounds. Most of the progress in understanding the lithium ion battery materials has been obtained from x-ray diffraction studies. Up to now, most XRD studies on lithium-ion battery materials have been done ex situ. Although these ex situ XRD studies have provided important information· about the structures of battery materials, they do face three major problems. First of all, the pre-selected charge (discharge) states may not be representative for the full picture of the structural changes during charge (discharge). In other words, the important information might be missed for those charge (discharge) states which were not selected for ex situ XRD studies. Secondly, the structure of the sample may have changed after removed from the cell. Finally, it is impossible to use the ex situ XRD to study the dynamic effects during high rate charge-discharge, which is crucial for the application of lithium-ion batteries for electric vehicle. A few in situ studies have been done using conventional x-ray tube sources. All of the in situ XRD studies using conventional x-ray tube sources have been done in the reflection mode in cells with beryllium windows. Because of the weak signals, data collection takes a long time, often several hundred hours for a single charge-discharge cycle. This long time data collection is not suitable for dynamic studies at all. Furthermore, in the reflection mode, the x-ray beam probes mainly the surface layer of the cathode materials. Iri collaboration with LG Chemical Ltd., BNL group designed and constructed the cells for in situ studies. LG Chemical provided several blended samples and pouch cells to BNL for preliminary in situ study. The LG Chemical provided help on integrate the blended cathode into these cells. The BNL team carried out in situ XAS and XRD studies on the samples and pouch cells provided by LG Chemical under normal charge-discharge conditions at elevated temperature.},
doi = {10.2172/973810},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed May 23 00:00:00 EDT 2007},
month = {Wed May 23 00:00:00 EDT 2007}
}

Technical Report:

Save / Share:
  • The object of this project is to develop new electrolyte and cathode materials for rechargeable lithium batteries, especially for lithium ion and lithium polymer batteries. Enhancing performance, reducing cost, and replacing toxic materials by environmentally benign materials, are strategic goals of DOE in lithium battery research. This proposed project will address these goals on two important material studies, namely the new electrolytes and new cathode materials. For the new electrolyte materials, aza based anion receptors as additives, organic lithium salts and plasticizers which have been developed by BNL team under Energy Research programs of DOE, will be evaluated by Gouldmore » for potential use in commercial battery cells. All of these three types of compounds are aimed to enhance the conductivity and lithium transference number of lithium battery electrolytes and reduce the use of toxic salts in these electrolytes. BNL group will be working closely with Gould to further develop these compounds for commercialization. For the cathode material studies, BNL efforts wi U be focused on developing new superior characterization methclds, especially in situ techniques utilize the unique user facility of DOE at BNL, namely the National Synchrotrons Light Source (NSLS). In situ x-ray absorption and x-ray diftlaction spectroscopy will be used to study the relationship between performance and the electronic and structural characteristics of intercalation compounds such as LiNi0 2, LiCo0 2, and LiMn 20 4 spinel. The study will be focused on LiMn 20 4 spinel materials. Gould team will contribute their expertise in choosing the most promising compounds, providing overall performance requirements, and will use the results of this study to guide their procedure for quality control. The knowledge gained through this project will not only benefit Gould and BNL, but will be very valuable to the scientific community in battery research.« less
  • The objective of the first year of this study was the investigation of two new classes of complex sulfide materials of potential value for ambient and high temperature, high energy rechargeable batteries with lithium anodes. The two new classes were the sulfospinels and simple and mixed layered disulfides of transitional metals of groups IVB and VB. In addition, three simple sulfides, CoS, CoS/sub 2/ and FeS/sub 2/ were also investigated. Studies of the synthesis methods have resulted in the development of the two-zone quartz furnace capable of firing temperatures up to 1000/sup 0/C with controllable sulfur vapor pressures. Optimum synthesismore » methods for preparation of TiS/sub 2/ and substituted disulfides of the type M/sub x/Ti/sub 1-x/S/sub 2/ (M = Co, Cr, Mo, V) as well as for sulfospinels have been established. In the area of mixed disulfides, compounds with 5 mole % molybdenum and 25 mole % chromium or vanadium were found to be superior in electrochemical cell performance to TiS/sub 2/. The higher electrical conductivity of these compounds compared to that of TiS/sub 2/ is the probable reason. The preparation of the Co-substituted disulfide was not successful and resulted in a sulfospinel structure of CoTi/sub 2/S/sub 4/. Among the sulfospinels studied CoCo/sub 2/S/sub 4/ = (Co/sub 3/S/sub 4/) and CoFe/sub 2/S/sub 4/, high capacity densities up to 605 mAH/g have been found with the former showing more electrochemical reversibility. The initial findings in organic electrolyte cells have been confirmed in high temperature tests conducted at Argonne National Laboratory in molten salt cell tests. The simple sulfides have been found to perform in organic electrolyte cells with CoS/sub 2/ showing lower polarization than FeS/sub 2/ or CoS.« less