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Effect of Lithium-Ion Concentration on Morphology and Ion Transport in Single-Ion-Conducting Block Copolymer Electrolytes

Journal Article · · Macromolecules
 [1];  [2];  [3];  [1];  [2];  [4];  [1]
  1. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  3. Univ. of California, Berkeley, CA (United States)
  4. Malvern Instruments Inc., Westborough, MA (United States)
Single-ion-conducting polymers are ideal electrolytes for rechargeable lithium batteries as they eliminate salt concentration gradients and concomitant concentration overpotentials during battery cycling. Here in this paper, we study the ionic conductivity and morphology of poly(ethylene oxide)-b-poly(styrenesulfonyllithium(trifluoromethylsulfonyl)imide) (PEO-b-PSLiTFSI) block copolymers with no added salt using ac impedance spectroscopy and small-angle X-ray scattering. The PEO molecular weight was held fixed at 5.0 kg mol-1, and that of PSLiTFSI was varied from 2.0 to 7.5 kg mol-1. The lithium ion concentration and block copolymer composition are intimately coupled in this system. At low temperatures, copolymers with PSLiTFSI block molecular weights ≤4.0 kg mol-1 exhibited microphase separation with crystalline PEO-rich microphases and lithium ions trapped in the form of ionic clusters in the glassy PSLiTFSI-rich microphases. At temperatures above the melting temperature of the PEO microphase, the lithium ions were released from the clusters, and a homogeneous disordered morphology was obtained. The ionic conductivity increased abruptly by several orders of magnitude at this transition. Block copolymers with PSLiTFSI block molecular weights ≥5.4 kg mol-1 were disordered at all temperatures, and the ionic conductivity was a smooth function of temperature. The transference numbers of these copolymers varied from 0.87 to 0.99. The relationship between ion transport and molecular structure in single-ion-conducting block copolymer electrolytes is qualitatively different from the well-studied case of block copolymers with added salt.
Research Organization:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Grant/Contract Number:
AC02-05CH11231
OSTI ID:
1513786
Journal Information:
Macromolecules, Journal Name: Macromolecules Journal Issue: 18 Vol. 48; ISSN 0024-9297
Publisher:
American Chemical SocietyCopyright Statement
Country of Publication:
United States
Language:
English

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Cited By (18)

Comparison of single-ion-conductor block-copolymer electrolytes with Polystyrene-TFSI and Polymethacrylate-TFSI structural blocks journal April 2018
Tuning the Properties of a UV-Polymerized, Cross-Linked Solid Polymer Electrolyte for Lithium Batteries journal March 2020
Gel Polymer Electrolytes for Electrochemical Energy Storage journal November 2017
Enabling High Lithium Conductivity in Polymerized Ionic Liquid Block Copolymer Electrolytes journal December 2018
Synthesis and Application of a Conjugated Polydianion‐Based Single‐Ion Conducting Polymer for High‐Performance Solid Lithium‐Ion Batteries journal April 2019
Poly(ethylene oxide)-based block copolymer electrolytes for lithium metal batteries: PEO-based BCEs for LMBs journal August 2018
Electrochemical performances of a new solid composite polymer electrolyte based on hyperbranched star polymer and ionic liquid for lithium-ion batteries journal April 2017
Stabilizing polymer electrolytes in high-voltage lithium batteries journal July 2019
Designing solid-state electrolytes for safe, energy-dense batteries journal February 2020
Single lithium-ion conducting solid polymer electrolytes: advances and perspectives journal January 2017
Nanostructured multi-block copolymer single-ion conductors for safer high-performance lithium batteries journal January 2018
Ionic conductivity and counterion condensation in nanoconfined polycation and polyanion brushes prepared from block copolymer templates journal January 2019
Confinement-entitled morphology and ion transport in ion-containing polymers journal January 2019
Single-ion conducting gel polymer electrolytes: design, preparation and application journal January 2020
Influence of pore morphology on the diffusion of water in triblock copolymer membranes journal January 2020
Block copolymers for supercapacitors, dielectric capacitors and batteries journal March 2019
Interrogation of Electrochemical Properties of Polymer Electrolyte Thin Films with Interdigitated Electrodes journal January 2018
Ion Transport in Solvent-Free, Crosslinked, Single-Ion Conducting Polymer Electrolytes for Post-Lithium Ion Batteries journal June 2018

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