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Title: Ordering transition in salt-doped diblock copolymers

Lithium salt-doped block copolymers offer promise for applications as solid electrolytes in lithium ion batteries. Control of the conductivity and mechanical properties of these materials, for membrane applications relies critically on the ability to predict and manipulate their microphase separation temperature. Past attempts to predict the so-called "order-disorder transition temperature" of copolymer electrolytes have relied on approximate treatments of electrostatic interactions. In this work, we introduce a coarse-grained simulation model that treats Coulomb interactions explicitly, and we use it to investigate the ordering transition of charged block copolymers. The order-disorder transition temperature is determined from the ordering free energy, which we calculate with a high level of precision using a density-of-states approach. Our calculations allow us to discern a delicate competition between two physical effects: ion association, which raises the transition temperature, and solvent dilution, which lowers the transition temperature. Lastly, in the intermediate salt concentration regime, our results predict that the order-disorder transition temperature increases with salt content, in agreement with available experimental data.
Authors:
 [1] ;  [1]
  1. Univ. of Chicago, Chicago, IL (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Published Article
Journal Name:
Macromolecules
Additional Journal Information:
Journal Volume: 49; Journal Issue: 9; Journal ID: ISSN 0024-9297
Publisher:
American Chemical Society
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1251444
Alternate Identifier(s):
OSTI ID: 1306537