Composition-structure-property-performance relationship inMn-substituted LiMn2O4

PDF Version Also Available for Download.

Description

The spinel LiMn{sub 2}O{sub 4} has been extensively studied as a positive electrode active material in lithium rechargeable batteries. Partial substitution of Mn by another metal has also been the subject of recent study in an effort to improve the cycling performance. In general, the literature has shown that Mn substitution results in improved cycling stability at the expense of capacity (1,2). Resistance to the formation of tetragonal phase upon lithiation of the starting spinel (via a higher nominal Mn oxidation state in the substituted spinel) has been suggested as a mechanism for the improved performance. The degree of substitution ... continued below

Creation Information

Horne, Craig R.; Richardson, Thomas J.; Gee, B.; Tucker, Mike; Grush, Melissa M.; Bergmann, Uwe et al. March 9, 2001.

Context

This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. More information about this article can be viewed below.

Who

People and organizations associated with either the creation of this article or its content.

Sponsor

Publishers

Provided By

UNT Libraries Government Documents Department

Serving as both a federal and a state depository library, the UNT Libraries Government Documents Department maintains millions of items in a variety of formats. The department is a member of the FDLP Content Partnerships Program and an Affiliated Archive of the National Archives.

Contact Us

What

Descriptive information to help identify this article. Follow the links below to find similar items on the Digital Library.

Description

The spinel LiMn{sub 2}O{sub 4} has been extensively studied as a positive electrode active material in lithium rechargeable batteries. Partial substitution of Mn by another metal has also been the subject of recent study in an effort to improve the cycling performance. In general, the literature has shown that Mn substitution results in improved cycling stability at the expense of capacity (1,2). Resistance to the formation of tetragonal phase upon lithiation of the starting spinel (via a higher nominal Mn oxidation state in the substituted spinel) has been suggested as a mechanism for the improved performance. The degree of substitution is an important factor to optimize in order to minimize capacity loss and costs. The spectroscopic investigations on LiMn{sub 2}O{sub 4} described in the previous paper (LixMn2O4) confirmed that the cooperative Jahn-Teller effect (CJTE) from the [Mn{sup 3+}O{sub 6}] octahedra is the mechanism for the cubic to tetragonal phase transformation. The driving force for the CJTE is based upon the electronic structure, therefore changes in electronic structure should lead to changes in the phase behavior. The fact that the LiMn{sub 1.5}Ni{sub 0.5}O{sub 4} does not form tetragonal phase upon discharging (FUJI3, MUCK?), unlike the 100% Mn{sup 4+} spinel Li{sub 4}Mn{sub 5}O{sub 12} (THAC5), led to the hypothesis that an increased degree of covalency as a source for the behavior. An increased covalence would remove the driving force for the transformation, the increased electronic stability achieved in tetragonally-distorted [Mn{sup 3+}O{sub 6}] octahedra, due to a change in electron density and widening of the Mn 3d bands. The STH field is dependent upon the amount of unpaired spin density transferred between the magnetic (transition-metal) and diamagnetic ions through an intermittent oxygen ion, attributable to overlap and electron transfer effects. Therefore, the magnitude of the STH coupling constant reflects the degree of covalency (GESC, HUAN). In the case of LiMn{sub 2-y}Me{sub y}O{sub 4}, the STH coupling constant characterizes the amount of unpaired spin density transferred to the Li{sup +} from the Mn, Co, or Ni. Similarly, the La/Lb ratio of the Mn L-XES is sensitive to the amount of electron density at the Mn site as a higher ratio indicates that the Mn 3d{sub 5/2} level is more populated (GRUS1). An investigation into the effects of Mn-substitution on the electronic structure along with the ramifications to the phase behavior upon changing lithium content was carried out. To accomplish this, a set of LiMn{sub 2-y}Me{sub y}O{sub 4} with Me = Li, Co, or Ni over a range of y were synthesized, characterized, and subjected to changes in lithium content by various techniques.

Source

  • ECS Fall 1999 Proceedings, Symposium B2,Honolulu, HI, Fall 1999

Language

Item Type

Identifier

Unique identifying numbers for this article in the Digital Library or other systems.

  • Report No.: LBNL--47601
  • Grant Number: DE-AC02-05CH11231
  • Office of Scientific & Technical Information Report Number: 860296
  • Archival Resource Key: ark:/67531/metadc778469

Collections

This article is part of the following collection of related materials.

Office of Scientific & Technical Information Technical Reports

What responsibilities do I have when using this article?

When

Dates and time periods associated with this article.

Creation Date

  • March 9, 2001

Added to The UNT Digital Library

  • Dec. 3, 2015, 9:30 a.m.

Description Last Updated

  • July 26, 2016, 3:34 p.m.

Usage Statistics

When was this article last used?

Yesterday: 0
Past 30 days: 0
Total Uses: 3

Interact With This Article

Here are some suggestions for what to do next.

Start Reading

PDF Version Also Available for Download.

Citations, Rights, Re-Use

Horne, Craig R.; Richardson, Thomas J.; Gee, B.; Tucker, Mike; Grush, Melissa M.; Bergmann, Uwe et al. Composition-structure-property-performance relationship inMn-substituted LiMn2O4, article, March 9, 2001; Pennington, New Jersey. (digital.library.unt.edu/ark:/67531/metadc778469/: accessed August 20, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.